NATIONAL CENTER FOR HEALTH STATISTICS

Vital and Health Statistics

 

NCHS reports can be downloaded from: https://www.cdc.gov/nchs/products/index.htm.

98.1 (0.93)

99.5 (0.26)

98.7 (0.75)

99.3 (0.73)

98.4 (1.49)

98.4 (1.58)

94.7 (1.95)

98.6 (1.30)

92.4 (2.88)

92.5 (2.46)

96.7 (2.48)

91.8 (3.61)

17.0 (0.46)

16.7 (0.55)

16.8 (1.01)

11.8 (2.48)

20.0 (1.88)

12.9 (1.13)

8.7 (1.26)

7.3 (2.20)

17.1 (4.43)

14.5 (3.05)

7.7 (2.11) 

3.8 (0.64) 

4.7 (1.03)

*2.4 (1.00)

84.5 (7.72)

*8.3 (3.48)

13.6 (2.00)

*3.9 (1.52)

17.5 (2.81)

*19.2 (7.52)

*18.5 (6.70)

*17.1 (4.85)

96.9 (0.21)

97.0 (0.24)

97.2 (0.44)

96.8 (1.27)

95.2 (0.88)

96.7 (0.78)

99.3 (0.29)

94.8 (1.66)

95.6 (1.39)

97.5 (1.40)

93.1 (2.60)

98.1 (0.93)

99.5 (0.26)

98.7 (0.75)

99.3 (0.73)

98.4 (1.49)

98.4 (1.58)

94.7 (1.95)

98.6 (1.30)

92.4 (2.88)

92.5 (2.46)

96.7 (2.48)

91.8 (3.61)

7.0 (0.24)

7.2 (0.44)

6.8 (1.27)

5.2 (0.88)

6.7 (0.78)

9.3 (0.29)

4.8 (1.66)

5.6 (1.39)

7.5 (1.40)

3.1 (2.60)

8.1 (0.93)

9.5 (0.26)

8.7 (0.75)

9.3 (0.73)

8.4 (1.49)

8.4 (1.58)

4.7 (1.95)

8.6 (1.30)

2.4 (2.88)

2.5 (2.46)

6.7 (2.48)

1.8 (3.61)

NATIONAL CENTER FOR HEALTH STATISTICS

Vital and Health Statistics

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

NCHS reports can be downloaded from: https://www.cdc.gov/nchs/products/index.htm.

Series 3, Number 44 January 2020 

The Impact of the Pregnancy 

Checkbox and Misclassification on 

Maternal Mortality Trends in the 

United States, 1999–2017 

Analytical and Epidemiological Studies 
Copyright information 

All material appearing in this report is in the public domain and may be reproduced or 

copied without permission; citation as to source, however, is appreciated. 

Suggested citation 

Rossen LM, Womack LS, Hoyert DL, Anderson RN, Uddin SFG. The impact of the pregnancy 

checkbox and misclassification on maternal mortality trends in the United States, 

1999–2017. National Center for Health Statistics. Vital Health Stat 3(44). 2020. 

For sale by the U.S. Government Publishing Office 

Superintendent of Documents 

Mail Stop: SSOP 

Washington, DC 20401–0001

Printed on acid-free paper. 
The Impact of the Pregnancy 

Checkbox and Misclassification 

on Maternal Mortality Trends in the 

United States, 1999–2017

Analytical and Epidemiological Studies

NATIONAL CENTER FOR HEALTH STATISTICS

Vital and Health Statistics

Series 3, Number 44 January 2020

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Hyattsville, Maryland

January 2020

DHHS Publication No. 2020–1428

The Impact of the Pregnancy 

Checkbox and Misclassification 

on Maternal Mortality Trends in the 

United States, 1999–2017

Analytical and Epidemiological Studies

NATIONAL CENTER FOR HEALTH STATISTICS

Vital and Health Statistics

Series 3, Number 44 January 2020

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Hyattsville, Maryland

January 2020

DHHS Publication No. 2020–1428
National Center for Health Statistics 

Jennifer H. Madans, Ph.D., Acting Director 

Amy M. Branum, Ph.D., Acting Associate Director for Science 

Division of Research and Methodology 

Jennifer D. Parker, Ph.D., Director 

Donald Malec, Ph.D., Associate Director for Science 

Division of Vital Statistics 

Steven Schwartz, Ph.D., Director 

Hanyu Ni, Ph.D., M.P.H., Associate Director for Science 
Series 3, Number 44 iii NATIONAL CENTER FOR HEALTH STATISTICS 

Contents

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Statistical Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

The Impact of the Implementation of the Pregnancy Checkbox on MMRs . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Observed and Predicted MMR Trends From 1999 Through 2017, Accounting for the Checkbox . . . . . . . . . . . . . . .9

The Impact of Potential Misclassification of Pregnancy Status on the Death Certificate on MMR Trends 

From 1999 Through 2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Impact of the Checkbox. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Misclassification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Appendix I. Supplemental Tables and Details of Adjustments to Maternal Mortality Ratios for Misclassification . . . . . . . 27

Appendix II. Supplemental Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Text Figures

1. Average change in maternal mortality rates associated with the pregnancy checkbox implementation:

United States, 2003–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2. Average change in maternal mortality rates associated with the pregnancy checkbox implementation, by age:

United States, 2003–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3. Average change in maternal mortality rates associated with the pregnancy checkbox implementation among

females aged 15–39, by age: United States, 2003–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4. Average change in maternal mortality rates associated with the pregnancy checkbox implementation, by race

and Hispanic origin: United States, 2003–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5. Average change in maternal mortality rates associated with the pregnancy checkbox implementation, by state

of occurrence: United States, 2003–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

6. Observed and predicted maternal mortality rates: United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7. Observed and predicted maternal mortality rates among females under age 15: United States, 1999–2017 . . . . . . . . . .10

8. Observed and predicted maternal mortality rates among females aged 15–19: United States, 1999–2017 . . . . . . . . . . .10

9. Observed and predicted maternal mortality rates among women aged 20–24: United States, 1999–2017 . . . . . . . . . . .11

10. Observed and predicted maternal mortality rates among women aged 25–29: United States, 1999–2017 . . . . . . . . . . .11

11. Observed and predicted maternal mortality rates among women aged 30–34: United States,

1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
 

 

 

 

 

 

 

Contents—Con.
 

12.	 Observed and predicted maternal mortality rates among women aged 35–39: United States, 1999–2017 . . . . . . . . . . . 12
 

13.	 Observed and predicted maternal mortality rates among women aged 40 and over: United States,
 

1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
 

14.	 Observed and predicted maternal mortality rates, by race and Hispanic origin: United States, 1999–2017 . . . . . . . . . . . 14
 

15.	 Observed and predicted maternal mortality rates, adjusted for an error rate of 0.25% in the pregnancy
 

checkbox: United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
 

16.	 Observed and predicted maternal mortality rates, adjusted for an error rate of 0.50% in the pregnancy
 

checkbox: United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
 

17.	 Observed and predicted maternal mortality rates, adjusted for an error rate of 1.00% in the pregnancy
 

checkbox: United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
 

Detailed Tables 

1.	 Average change in maternal mortality rates associated with the pregnancy checkbox implementation, by
 

age and race and Hispanic origin: United States, 2003–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
 

2.	 Trends in predicted maternal mortality rates, by age and race and Hispanic origin: United States, 1999–2017 . . . . . 23
 

3.	 Estimated impact of the pregnancy checkbox on cause-specific maternal mortality rates: United States,
 

2003–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
 

4.	 Estimated trends in predicted maternal mortality rates, by cause of death: United States, 1999–2017. . . . . . . . . . 25
 

5.	 Estimated average change in the percentage of all deaths due to nonmaternal causes of death associated
 

with the implementation of the revised standard death certificate, by age: United States, 2003–2017. . . . . . . . . . 26
 

Appendix Figures 

I.	 Observed and predicted maternal mortality rates for direct causes of maternal death: United States,
 

1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
 

II.	 Observed and predicted maternal mortality rates for direct causes of maternal death, excluding O26.8:
 

United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
 

III.	 Observed and predicted maternal mortality rates for direct causes of maternal death (A34, O00–O92):
 

United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
 

IV.	 Observed and predicted maternal mortality rates for direct causes of maternal death (A34, O00–O95):
 

United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
 

V.	 Observed and predicted maternal mortality rates for pregnancy with abortive outcomes (O00–O07):
 

United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
 

VI.	 Observed and predicted maternal mortality rates for edema, proteinuria, and hypertensive disorders in
 

pregnancy, childbirth, and the puerperium (O10–O16): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . 37
 

VII.	 Observed and predicted maternal mortality rates for other maternal disorders predominantly related to
 

pregnancy (O20–O29): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
 

VIII.	 Observed and predicted maternal mortality rates for liver disorders in pregnancy, childbirth, and the
 

puerperium (O26.6): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
 

IX.	 Observed and predicted maternal mortality rates for other specified pregnancy-related conditions (O26.8):
 

United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
 

NATIONAL CENTER FOR HEALTH STATISTICS iv	 Series 3, Number 44
 
 

 

 

 

 

 

 

 

 

 

 

 

Contents—Con.
 

X.	 Observed and predicted maternal mortality rates for other maternal disorders predominantly related to 

pregnancy (O20–O29), excluding nonspecific O26.8: United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . 39
 

XI.	 Observed and predicted maternal mortality rates for maternal care related to the fetus and amniotic cavity 

and possible delivery problems (O30–O48): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
 

XII.	 Observed and predicted maternal mortality rates for complications of labor and delivery (O60–O75): 

United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
 

XIII.	 Observed and predicted maternal mortality rates for complications predominantly related to the 

puerperium (O85–O92): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
 

XIV.	 Observed and predicted maternal mortality rates for indirect causes of maternal death: 

United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
 

XV.	 Observed and predicted maternal mortality rates for alternative grouping of indirect causes of 

maternal death (O98–O99): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
 

XVI.	 Observed and predicted maternal mortality rates for other obstetric conditions not elsewhere classified, 

including late maternal deaths (O95–O99): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
 

XVII.	 Observed and predicted maternal mortality rates for other obstetric conditions not elsewhere classified, 

excluding late maternal deaths (O95, O98–O99): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . 42
 

XVIII.	 Observed and predicted maternal mortality rates for mental disorders and diseases of the nervous system 

complicating pregnancy, childbirth, and the puerperium (O99.3): United States, 1999–2017 . . . . . . . . . . . . . . . . . 43
 

XIX.	 Observed and predicted maternal mortality rates for diseases of the circulatory system complicating 

pregnancy, childbirth, and the puerperium (O99.4): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . 43
 

XX.	 Observed and predicted maternal mortality rates for diseases of the respiratory system complicating 

pregnancy, childbirth, and the puerperium (O99.5): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . 44
 

XXI.	 Observed and predicted maternal mortality rates for other specified diseases and conditions complicating 

pregnancy, childbirth, and the puerperium (O99.8): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . 44
 

XXII.	 Observed and predicted maternal mortality rates for late maternal deaths (O96–O97): 

United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
 

XXIII.	 Observed and predicted maternal mortality rates for nonspecific causes of maternal death (O26.8, O95, 

O99.8): United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
 

XXIV.	 Observed and predicted maternal mortality rates among females aged 15–19, adjusted for an error rate of 

0.50% in the pregnancy checkbox: United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
 

XXV.	 Observed and predicted maternal mortality rates among women aged 20–24, adjusted for an error rate of 

0.50% in the pregnancy checkbox: United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
 

XXVI.	 Observed and predicted maternal mortality rates among women aged 25–29, adjusted for an error rate of 

0.50% in the pregnancy checkbox: United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
 

XXVII.	 Observed and predicted maternal mortality rates among women aged 30–34, adjusted for an error rate of 

0.50% in the pregnancy checkbox: United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
 

XXVIII. Observed and predicted maternal mortality rates among women aged 35–39, adjusted for an error rate of 

0.50% in the pregnancy checkbox: United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
 

XXIX.	 Observed and predicted maternal mortality rates among women aged 40 and over, adjusted for an error 

rate of 0.50% in the pregnancy checkbox: United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
 

Series 3, Number 44	 v NATIONAL CENTER FOR HEALTH STATISTICS 
 

 

Contents—Con.
 

XXX.	 Observed and predicted maternal mortality rates, by race and Hispanic origin, adjusted for an error rate of 

0.50% in the pregnancy checkbox: United States, 1999–2017. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
 

Appendix Tables 

I.	 Percentage of deaths among female decedents under 10 years or 55 and over where one of the 

pregnancy checkboxes was selected, by state of occurrence: 2003–2013 . . . . . . . . . . . . . . . . . . . . . . . . 27
 

II.	 Change in maternal mortality rates associated with the pregnancy checkbox implementation, by 

state of occurrence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
 

III.	 Observed and predicted maternal mortality rates: United States, 1999–2017 . . . . . . . . . . . . . . . . . . . . . . 30
 

IV.	 Predicted maternal mortality rates, adjusted for outcome misclassification: United States, 1999 and 2017 . . . . . 31
 

V.	 Comparison of pregnancy status on death certificates with pregnancy status assessed by 

a gold standard measure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
 

NATIONAL CENTER FOR HEALTH STATISTICS vi	 Series 3, Number 44
 
Acknowledgments
 

The authors are grateful for the insightful reviews and 

comments provided by Jennifer Madans and Amy Branum, 

National Center for Health Statistics (NCHS) Office of the 

Director; Don Malec, Jennifer Parker, Jennifer Rammon, 

and Katherine Irimata, NCHS Division of Research and 

Methodology; and Hanyu Ni and Isabelle Horon, NCHS 

Division of Vital Statistics. 

Series 3, Number 44 vii NATIONAL CENTER FOR HEALTH STATISTICS 
The Impact of the Pregnancy Checkbox 

and Misclassification on Maternal Mortality 

Trends in the United States, 1999–2017 

by Lauren M. Rossen, Ph.D., M.S., Lindsay S. Womack, Ph.D., M.P.H., Donna L. Hoyert, Ph.D., Robert N. Anderson, 

Ph.D., and Sayeedha F.G. Uddin, M.D., M.P.H. 

Abstract 

Background 

National maternal mortality rates (MMRs) using 

mortality data from the National Vital Statistics 

System have not been reported since 2007 due to the 

staggered implementation of the 2003 U.S. Standard 

Certificate of Death between 2003 and 2017, which 

added a checkbox to determine pregnancy status at the 

time of death. This report evaluates the impact of the 

staggered implementation of the pregnancy checkbox 

and potential outcome misclassification on MMRs and 

related trends from 1999 through 2017. 

Methods 

Log-binomial regression models were used to examine 

the impact of the staggered implementation of the 

pregnancy checkbox by states over time and to predict 

MMRs under two alternative scenarios: (1) assuming 

that no states had the checkbox at any point, and 

(2) assuming that all states had the checkbox from 

1999 through 2017. The impact of the checkbox and 

related trends over time were examined by age, race 

and Hispanic origin, state of occurrence, and causes 

of maternal death. Sensitivity analyses examined the 

impact of outcome misclassification. 

Results 

The implementation of the checkbox was associated with 

an increased identification of maternal deaths. Averaging 

over the period 2003–2017, the checkbox resulted in 

an MMR increase of 9.6 deaths per 100,000 live births 

(95% confidence interval: 8.6–10.6). The average impact 

of the checkbox adoption was greater for women aged 

40 and over, non-Hispanic black women, and for certain 

causes of death. Accounting for the checkbox, predicted 

MMRs did not change significantly from 1999 through 

2017, although trends varied by subgroup (age, race and 

Hispanic origin, cause of death). 

Conclusions 

Estimated trends suggest that the observed increases in 

MMRs from 1999 through 2017 reported in the literature 

were largely due to the staggered implementation of the 

checkbox. Potential misclassification of pregnancy status 

using the pregnancy checkbox likely also contributed, 

which disproportionately inflated MMRs among women 

aged 40 and over. 

Keywords: death certificate • epidemiologic methods • 

maternal death • National Vital Statistics System 

Introduction 

Maternal mortality is a critical indicator of population 

health in both the United States and internationally (1–3). 

Monitoring maternal mortality over time is important to 

evaluate progress in improving maternal health in the United 

States, to make international comparisons, and to examine 

differences and inequities by demographic subgroup (3). 

Substantial disparities in maternal mortality exist by race and 

Hispanic origin and age in the United States (4–6). Maternal 

and pregnancy-related mortality rates for non-Hispanic 

black women are approximately three times the rates for 

non-Hispanic white women, while women aged 40 and over 

have the highest maternal mortality rates compared with 

other age groups (4,6,7). 

The National Vital Statistics System (NVSS) is the official 

source for U.S. maternal mortality statistics used in 

international, state, and demographic comparisons. NVSS 

is used to tabulate the number of maternal deaths, defined 

by the World Health Organization (WHO) as the “death of 

a woman while pregnant or within 42 days of termination 

of pregnancy, irrespective of the duration and site of the 

pregnancy, from any cause related to or aggravated by the 

pregnancy or its management but not from accidental or 

incidental causes” (3). Of note, this is different from the 

Centers for Disease Control and Prevention definition of 

pregnancy-related deaths, defined as the death of a woman 

while pregnant or within 1 year of pregnancy termination— 

regardless of the duration or site of the pregnancy—from 

any cause related to or aggravated by the pregnancy or its 

Series 3, Number 44 1 NATIONAL CENTER FOR HEALTH STATISTICS 
management, but not from accidental or incidental causes; 

and from pregnancy-associated deaths, defined as all deaths 

during pregnancy or within 1 year of pregnancy, regardless 

of cause. 

Examinations of maternal deaths prior to 2000 suggested 

substantial underreporting of maternal deaths in NVSS 

(8–12). To improve identification of maternal deaths, a 

pregnancy question was added to the 2003 revision of the 

U.S. Standard Certificate of Death. This pregnancy question 

includes a series of checkboxes to determine whether female 

decedents were currently or recently pregnant (within 42 

days, or 43 days to 1 year). Jurisdictions adopted this revision 

at different times between 2003 and 2017, making it difficult 

to estimate national-level trends in maternal mortality 

over this time period (13,14). Subsequently, national 

maternal mortality rates (MMRs) have not been reported 

since 2007. Studies have suggested that the pregnancy 

checkbox resulted in the identification of more maternal or 

pregnancy-associated deaths (8,15). A companion report 

examines the impact of the pregnancy checkbox by recoding 

cause of death without consideration of the checkbox, using 

data on maternal deaths from 2015 through 2016 (15). 

Findings suggest that the number of maternal deaths was 

approximately three times higher when using information 

from the checkbox compared with the recoded data without 

considering the checkbox (15). Differences were seen in the 

magnitude of the impact of the checkbox by maternal age, 

race and Hispanic origin, and cause of death. Specifically, 

among women aged 40 and over, the number of maternal 

deaths reported with the checkbox was more than 14 times 

higher than the number reported without using information 

from the checkbox. That companion report offers additional 

detail about the coding of maternal deaths and differences 

in the impact of the checkbox by cause of death. 

Given the substantial impact of the checkbox on the 

identification of maternal deaths, estimating trends in 

maternal mortality considering its staggered implementation 

across the United States has proved challenging. Several 

studies have attempted to account for the checkbox in 

examinations of recent trends in maternal mortality. 

MacDorman et al. examined trends from 2000 through 2014 

and reported that MMRs (maternal deaths per 100,000 

live births) increased by nearly 30%, from 18.8 in 2000 to 

23.8 in 2014; however, these estimates excluded California 

and Texas, and correction factors (to account for changes in 

measurement associated with the checkbox) were calculated 

based on 24 states and the District of Columbia (14). Joseph 

et al. suggested that most of the increase in MMRs from 

1993 through 2014 was due to the implementation of the 

checkbox and that increases were limited to nonspecific 

causes of maternal death (16). Davis et al. reported that 

90% of the increase from 1998–2002 through 2008–2012 

was due to the implementation of the pregnancy checkbox, 

comparing a subset of 23 states that adopted the checkbox 

with a group of 11 states that had not (17). Another study 

suggested that only 31% of the increase in MMRs from 1997 

through 2012 was attributable to the 2003 death certificate 

revision (18) but was limited to the 36 states that had adopted 

the revision by 2012. Because prior studies examining the 

impact of the pregnancy checkbox have typically looked at 

subsets of states (4,14,17), the impact of the checkbox on 

national trends since 1999 remains unclear; 2017 is the first 

year that all states have adopted the 2003 revision of the 

certificate, allowing for examination of national-level data. 

Although pregnancy checkboxes have been found to identify 

a greater percentage of deaths during or following pregnancy 

(8,19), some reports suggest that approximately 14% of 

pregnancy-associated deaths had no verifiable evidence of 

pregnancy (20). Therefore, misclassification of pregnancy 

status on death certificates may have contributed to biased 

trend estimates (19,21,22). An examination of Texas MMRs 

reported increases from 2006 through 2015, but the extent 

to which the increase was driven by overreporting of 

maternal deaths was unclear, particularly among women 

aged 40 and over (23). A review of 147 maternal deaths in 

Texas suggested that approximately one-half of obstetriccoded deaths had no evidence of pregnancy within 42 days 

of death, with 67% of the deaths among women aged 35 

and over showing no evidence of pregnancy (24). Davis et 

al. also suggested that a high degree of misclassification 

of pregnancy status among women aged 40 and over may 

explain the increasing trends seen among this age group. 

The impact of potential misclassification of pregnancy status 

on MMRs among all states incorporating the pregnancy 

checkbox has not been explored. 

The objectives of this analysis were to (1) quantify the 

impact of the staggered implementation of the pregnancy 

checkbox on MMRs overall and by maternal age, race and 

Hispanic origin, cause of death, and state; (2) estimate 

trends in MMRs from 1999 through 2017, accounting for the 

checkbox, overall and by maternal age, race and Hispanic 

origin, and cause of death; and (3) examine the impact of 

potential misclassification of pregnancy status on the death 

certificate on trends in MMRs from 1999 through 2017. 

Methods 

Data 

Data on maternal deaths and births were drawn from NVSS 

for the years 1999 through 2017. Maternal deaths for each 

year were identified using International Classification of 

Diseases, 10th Revision (ICD–10) underlying-cause codes 

A34, O00–O95, and O98–O99, consistent with the WHO 

definition. Late maternal deaths (those occurring more 

than 42 days following pregnancy) were identified using 

the underlying-cause codes O96 and O97, and analyzed 

separately. Denominators for maternal mortality rates were 

calculated from NVSS birth data for 1999 through 2017 (25). 

Maternal deaths and corresponding numbers of live births 

were aggregated by year, state of occurrence, race and 

NATIONAL CENTER FOR HEALTH STATISTICS 2 Series 3, Number 44 
Hispanic origin (non-Hispanic white, non-Hispanic black, 

Hispanic, non-Hispanic other), and age group (under 15, 

15–19, 20–24, 25–29, 30–34, 35–39, 40 and over). State 

of occurrence, rather than residence, was used because 

the death certificate information (and consequently, the 

pregnancy checkbox) is collected using the certificate issued 

by state of occurrence. 

Causes of maternal death 

Prior studies suggested that the impact of the pregnancy 

checkbox varied by cause of death (4,16). Subsequently, 

analyses examined the impact of the checkbox and related 

trends over time by various causes (and groups of causes) of 

maternal deaths: 

● O00–O07: Pregnancy with abortive outcomes 

● O10–O16: Edema, proteinuria and hypertensive disorders 

in pregnancy, childbirth and the puerperium 

● O20–O29: Other maternal disorders predominantly 

related to pregnancy 

● O26.6: Liver disorders in pregnancy, childbirth and the 

puerperium 

● O26.8: Other specified pregnancy-related conditions 

● O30–O48: Maternal care related to the fetus and 

amniotic cavity and possible delivery problems 

● O60–O75: Complications of labor and delivery 

● O85–O92: Complications predominantly related to the 

puerperium 

● O95–O99: Other obstetric conditions not elsewhere 

classified (including late maternal deaths) 

● O95, O98–O99: Other obstetric conditions not elsewhere 

classified (excluding late maternal deaths) 

● O96–O97: Late maternal deaths 

● O99.3: Mental disorders and diseases of the nervous 

system complicating pregnancy, childbirth and the 

puerperium 

● O99.4: Diseases of the circulatory system complicating 

pregnancy, childbirth and the puerperium 

● O99.5: Diseases of the respiratory system complicating 

pregnancy, childbirth and the puerperium 

● O99.8: Other specified diseases and conditions 

complicating pregnancy, childbirth and the puerperium 

● Direct causes (26)

● Indirect causes (26)

● O26.8, O95, O99.8: Nonspecific causes 

● A34, O00–O92: Alternative grouping of direct causes (4)

● O98–O99: Alternative grouping of indirect causes (4)

● A34, O00–O95: Alternative grouping of direct causes (15)

Statistical Analysis 

Objective 1: Quantify the impact of the 

staggered implementation of the pregnancy 

checkbox on MMRs 

A regression-discontinuity approach was used to examine 

the impact of adopting the pregnancy checkbox on maternal 

mortality rates overall, by demographic group, and by cause 

of death. Regression-discontinuity designs can be used to 

examine the causal effects of a given intervention when the 

exposure to that intervention is based on a specific threshold 

(27). Assuming that observations immediately below and 

above the threshold are otherwise similar, the difference at 

the threshold corresponds to the causal effect estimate of 

that intervention (27–29). By examining MMRs immediately 

prior to and after the implementation of the checkbox, the 

impact of the checkbox on MMRs can be estimated. 

First, a variable was created by subtracting the year that 

states revised their certificates (30) from the year of death. 

This variable represents time since revision year, equal to zero 

in the year that the state revised. This variable represents 

the threshold value used in a regression-discontinuity 

analysis—states and other factors related to maternal 

mortality are assumed to be otherwise similar immediately 

before and after the revision, the major difference being the 

addition of the pregnancy checkbox. To examine the impact 

of the checkbox visually, MMRs were plotted against the 

“time since revision” variable using fractional polynomial 

prediction plots in Stata 14 SE (College Station, Tex.), which 

allows for nonlinear trends. Plots were limited to show 

trends within plus or minus 4 years of the revision, with 

the discontinuity between the lines pre- and postrevision 

(when “time since revision” is equal to zero) representing 

the impact of the checkbox on MMRs. Four years before 

and after the implementation of the checkbox are shown 

to visually inspect any potential temporal trends prior to or 

following the checkbox. 

Frequency-weighted log-binomial regression models with 

robust standard errors were implemented using Stata 14 

SE to examine whether the impact of the checkbox differed 

by various demographic characteristics. These models also 

were used to estimate trends over time, accounting for the 

staggered adoption of the pregnancy checkbox by states 

from 2003 through 2017. MMRs were modeled as a function 

of revision status, state of occurrence, year, age group, and 

race and Hispanic origin. Additionally, interactions between 

revision status and state, age group, and race and Hispanic 

origin were included to allow for the impact of the checkbox 

to vary by these factors. Interactions between year and 

state of occurrence, age group, and race and Hispanic origin 

allowed temporal trends to vary by these factors. Finally, 

models including indicators for whether a given state had a 

pregnancy question prior to the checkbox implementation 

(Alabama, Florida, Illinois, Indiana, Iowa, Kentucky, Louisiana, 

Maryland, Minnesota, Mississippi, Missouri, Nebraska, 

Series 3, Number 44 3 NATIONAL CENTER FOR HEALTH STATISTICS 
New Jersey, New Mexico, New York City, New York State, 

North Dakota, Texas, and Virginia), and for when coding 

was centralized at the National Center for Health Statistics 

(NCHS) in 2011, also were explored to assess whether 

MMRs and the impact of the revision varied by these 

factors. California was not included in the set of states with 

pregnancy questions prior to the checkbox implementation, 

because it uses a question that is inconsistent with the 2003 

standard certificate, asking about pregnancy status in the 

past 12 months. 

Average marginal effects were used to estimate the change 

in the MMRs associated with the revision overall, and by age 

group, race and Hispanic origin, state of occurrence, causeof-death grouping, and whether the state had a pregnancy 

question on the death certificate prior to the revision. 

All analyses were conducted using Stata 14 SE, and no 

adjustments were made for multiple comparisons. 

Objective 2: Estimate trends in MMRs from 1999 

through 2017, accounting for the checkbox 

To examine trends from 1999 through 2017, maternal 

mortality rates were predicted based on two scenarios: (1)

assuming that no states had adopted the checkbox and (2)

assuming that all states had implemented the checkbox 

throughout the entire study period. Observed and predicted 

trends were estimated overall and by age group, race and 

Hispanic origin, state of occurrence, and cause-of-death 

group. Average marginal effects were used to estimate the 

linear time trends overall and by group, adjusted for the 

factors included in the models (e.g., age, race and Hispanic 

origin, state, revision status). These average marginal 

effects represent the estimated annual absolute change in 

the MMRs under the two scenarios described previously, 

controlling for sociodemographic factors such as age, race 

and Hispanic origin, and state. 

Objective 3: Examine the impact of potential 

misclassification of pregnancy status on the 

death certificate on MMR trends from 1999 

through 2017 

Several additional analyses were conducted to examine the 

potential impact of misclassification (31,32) of pregnancy 

status on MMRs and related trends (see Appendix I for more 

details). Prior studies have suggested that the pregnancy 

checkbox resulted in many deaths being classified as maternal 

(or pregnancy-associated) when there was no evidence 

of pregnancy, with false-positive rates as high as 50% 

(13,17–24,33–35). Other studies have described substantial 

false-negative rates (failure to identify pregnancy on death 

certificates) both before and after the implementation of 

the checkbox (8,12,22,34,36,37). 

Accounting for a certain percentage of death certificates 

where a pregnancy checkbox may have been selected in 

error 

To determine a plausible range for the error rate, the 

percentage of records where one of the pregnancy checkboxes 

was selected (either currently pregnant, pregnant within 42 

days, or pregnant 43 days to 1 year) among women of ages 

where pregnancy would be implausible (age 10 years and 

under or 55 and over) was calculated by state of occurrence. 

There was variability by state in the percentage of records 

where this occurred, with the largest percentages in North 

Dakota, California, New Jersey, Oklahoma, Michigan, New 

York State (excluding New York City), Kentucky, Tennessee, 

Utah, the District of Columbia, New Hampshire, Rhode 

Island, and Texas (ranging from 0.05% to 0.34%; see Table I). 

Models were run assuming that 0.25%, 0.50%, or 1.00% of 

death certificates for female decedents had a pregnancy 

checkbox selected in error (currently pregnant or pregnant 

within 42 days). These percentages were used to adjust 

the observed numbers of maternal deaths. For each state, 

age, and racial or Hispanic-origin group, these percentages 

(expressed as proportions) were multiplied by the total 

number of deaths among females aged 15–44 in that 

group to estimate the number of overall death records 

that may have a checkbox marked in error. These numbers 

were subtracted from the observed numbers of maternal 

deaths in each stratum (among states and years where the 

checkbox applied), and the models were refit. Because more 

deaths occur among older women, this adjustment had a 

disproportionate impact on MMRs among older age groups, 

even assuming a constant error rate of 0.25%, 0.50%, or 

1.00%. 

Adjusting for outcome misclassification 

Additionally, MMRs were corrected for potential outcome 

misclassification based on prior validation studies examining 

the accuracy of death record data in identifying maternal 

deaths, conducted before the implementation of the 

checkbox (8,9,11,12,38) and after (13,17–24,33–35). 

These studies have provided a range of values for the 

sensitivity (Se) of death certificate data (the proportion of 

true maternal deaths captured in death certificate data), 

predictive value positive (PVP; the proportion of maternal 

deaths determined using death certificate data that are true 

maternal deaths), or false-positive rates (the proportion of 

maternal deaths determined using death certificate data 

that are not maternal deaths). 

A data visualization tool (available from: https://www.cdc. 

gov/nchs/maternal-mortality/dashboard/) was developed 

to explore the impact of potential misclassification on MMR 

trends overall and by demographic group, allowing users 

to vary Se and false-positive rates within plausible ranges 

(0.4–1.0 for Se, 0.00–0.75 for false-positive rates). The 

following formula was used to adjust the predicted MMRs 

NATIONAL CENTER FOR HEALTH STATISTICS 4 Series 3, Number 44 
based on Se and PVP values (where PVP is equal to 1–falsepositive rate; see Appendix I for more detail): 

# Maternal Deathsobs • PVP # Maternal Deathsadj = (1) Se 

Because the Se and PVP values differed before and after the 

implementation of the checkbox, values defined for the 

period prior to the checkbox implementation were applied 

to the predicted MMRs assuming that no states adopted the 

checkbox, while values defined for the period after the 

checkbox implementation were applied to the predicted 

MMRs assuming that all states had adopted the checkbox 

throughout 1999–2017. 

Falsification test: Nonmaternal causes of death 

Finally, the impact of the checkbox was examined for several 

nonmaternal causes of death, including unintentional 

injuries, suicide, homicide, drug overdose, and unknown 

or ill-specified (R99). These are not maternal causes of 

death according to the WHO definition, and so, should not 

necessarily have changed because of the adoption of the 

checkbox. However, in some cases, deaths due to these 

causes may be coded as a maternal death due to ICD–10 

coding rules relating to what information appears on the 

death certificate and where it appears (15,39,40). To explore 

whether changes in these nonmaternal causes were a result 

of the implementation of the checkbox, two sets of models 

were run. 

First, the percentage of overall deaths among women of 

reproductive age (15–44 years) due to these causes was 

modeled using the same frequency-weighted log-binomial 

models described previously. The estimated impact of the 

checkbox refers to the change in the percentage of deaths 

among women of reproductive age due to these five causes. 

Second, as a falsification test, these same models were run 

for females under age 10 or 55–59, where there should be 

no impact of the checkbox because it does not apply to 

these age groups in determining the underlying cause-ofdeath code. If changes in the percentages of deaths among 

these groups occurred due to these causes, then it would 

suggest that there are factors confounding the estimates of 

the impact of the pregnancy checkbox (e.g., the adoption 

of electronic death registration systems, or other data 

quality improvements that may have occurred at the same 

time as the adoption of the revised standard certificate). 

Finally, if there were declines in the percentages of deaths 

due to these external causes (and unknown or ill-specified 

causes) among women of reproductive age associated with 

the implementation of the checkbox, then it could suggest 

that the coding changes instituted with the implementation 

of the checkbox resulted in a certain percentage of these 

deaths being assigned a maternal cause of death. 

Results 

The Impact of the Implementation of the 

Pregnancy Checkbox on MMRs 

Overall, the addition of the pregnancy checkbox on the 

2003 standard death certificate, which was implemented 

in staggered fashion across the United States from 2003 

through 2017, was associated with an average increase of 

9.6 maternal deaths per 100,000 live births (95% confidence 

interval [CI]: 8.6–10.6). Figure 1 shows the trends in MMRs 

prior to and immediately after the implementation of the 

checkbox. 

The average impact of the revision varied by maternal age, 

race and Hispanic origin, and state of occurrence. For females 

aged 15–34, the implementation of the checkbox resulted in 

an increase in the age-specific MMRs ranging from 3.7 (95% 

CI: 1.7–5.7) among teenagers (ages 15–19) to 6.0 (95% CI: 

3.9–8.0) among women (ages 30–34) (Table 1; Figures 2 and 

3). For women aged 35–39, MMRs increased by 13.9 (95% 

CI: 9.7–18.0). The impact of the checkbox on MMRs among 

women over 40 was much larger than for other age groups, 

with an increase of 145.3 (95% CI: 127.6–163.1). By race and 

Hispanic origin, the checkbox was associated with increases 

of 6.2 (95% CI: 4.3–8.1) among Hispanic women, 7.1 (95% 

CI: 4.2–10.0) among non-Hispanic women of other races, 8.6 

(95% CI: 7.5–9.7) among non-Hispanic white women, and 

19.6 (95% CI: 15.3–24.0) among non-Hispanic black women 

(Table 1; Figure 4). 

The impact of the checkbox was smaller among states that 

had a question about pregnancy status prior to the adoption 

of the revised standard certificate (8.1, 95% CI: 6.8–9.4) than 

among states that did not have a pregnancy question (9.8, 

95% CI: 8.7–10.9). Additionally, the impact of the revision 

was larger after the coding of cause of death was centralized 

at NCHS in 2011 (10.9, 95% CI: 9.5–12.2) compared with 

before (9.0, 95% CI: 8.0–10.0). 

Differences by state of occurrence were seen in the impact 

of the checkbox, with most states exhibiting increases 

in MMRs, except Maryland, where the MMR declined 

(Figure 5; Table II). The point estimates for Mississippi, 

Hawaii, Wisconsin, Nebraska, Pennsylvania, Nevada, and 

Rhode Island also indicated that MMRs declined as a result 

of the checkbox, but the CIs around these estimated changes 

were wide, and the 95% CI bounds were compatible with the 

possibility that MMRs increased or did not change as a result 

of the checkbox. The largest increases in MMRs as a result of 

the checkbox were seen in Louisiana, Oklahoma, Michigan, 

Alabama, Idaho, Indiana, Ohio, Tennessee, South Carolina, 

Illinois, New Jersey, and Arkansas (all increased by more 

than 15 maternal deaths per 100,000 live births). Wyoming, 

North Dakota, and Delaware also exhibited increases of 15 

or more, but the CIs around these estimates were wide due 

to the small number of events in these states, and the 95% 

Series 3, Number 44 5 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTE: Figure was generated using fractional polynomial prediction plots in Stata 14 SE, with shaded areas corresponding to 95% confidence intervals.

SOURCE: NCHS, National Vital Statistics System.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Figure was generated using fractlonal polynomlal prediction plolB In state 14 SE, with shaded areas corresponding to95% confidence lntarvals. 

SOURCE: NCHS, National Vital Statistics System. 

SOURCE: SOURCE: NCHS, NCHS, National National Vdal Vital Statistics Statistics System. System. 

Figure 1. Average change in maternal mortality rates associated with the pregnancy checkbox implementation: 

United States, 2003–2017 

Figure 2. Average change in maternal mortality rates associated with the pregnancy checkbox implementation, by 

age: United States, 2003–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 6 Series 3, Number 44 
SOURCE: NCHS, National Vital Statistics System.

SOURCE: NCHS, National Vital Statistics System.

SOURCE: NCHS, National Vdal Statistics System. 

SOURCE: NCHS, National Vrtal Statistics System. 

Figure 3. Average change in maternal mortality rates associated with the pregnancy checkbox implementation among 

females aged 15–39, by age: United States, 2003–2017 

Figure 4. Average change in maternal mortality rates associated with the pregnancy checkbox implementation, by 

race and Hispanic origin: United States, 2003–2017 

Series 3, Number 44 7 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTE: Wyoming was excluded as the estimate was highly unstable (95% confidence interval: -22.48-191.33).

SOURCE: NCHS, National Vital Statistics System.

NOTE: Wyoming was excluded aa Ille eatlmsta was hlghly unstable (95% confidence Interval: -22.4&--191.33). 

SOURCE: NCHS, National Vital Statistics Systam. 

NOTE: Wyoming was excluded as the estimate was highly unstable (95% confidence interval: -22.48-191.33). 

NATIONAL CENTER FOR HEALTH STATISTICS 8 Series 3, Number 44

Figure 5. Average change in maternal mortality rates associated with the pregnancy checkbox implementation, by 

state of occurrence: United States, 2003–2017

 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models Mre adjusted fer age group, race and Hisparicorigin, and state of occurrence, and included interactions between these factors and year as Mii as revision status. 

SOURCE: NCHS, National Vital Statistics System. 

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status. 

SOURCE: NCHS, National Vital Statistics System. 

CI bounds were compatible with the possibility that MMRs 

either declined or did not change as a result of the checkbox. 

Observed and Predicted MMR Trends From 

1999 Through 2017, Accounting for the 

Checkbox 

Figure 6 illustrates the overall trends in the observed 

MMRs and in the predicted MMRs, assuming that no 

states had adopted the checkbox during this time period, 

and in the predicted MMRs, assuming that all states 

had adopted the checkbox during this time period. Both 

with and without the checkbox, no significant change 

in the MMRs was observed in adjusted models (−0.03, 

95% CI: −0.09−0.03, p = 0.307; 0.04, 95% CI: −0.07–0.15, 

p = 0.459, respectively). Without the checkbox, estimated 

MMRs were 10.3 maternal deaths per 100,000 live births in 

1999 and 12.8 in 2017 (Table IV). Assuming that all states 

had adopted the checkbox in 1999, estimated MMRs were 

21.2 in 1999 and 23.5 in 2017. Of note, unadjusted trend 

estimates accounting only for revision status by state 

showed an average annual increase in MMRs both without 

the checkbox (0.12, 95% CI: 0.06–0.18, p < 0.001) and with 

the checkbox (0.22, 95% CI: 0.12–0.32, p < 0.001). 

Figures 7–13 show trends by age group. No significant 

changes in predicted MMRs were seen with or without the 

checkbox for the youngest groups (under 15 and 15–19) 

(Table 2; Figures 7 and 8). Without the checkbox, predicted 

MMRs declined for women aged 20–24 (−0.1 per year, 95% 

CI: −0.2 – −0.0, p = 0.001; see Figure 9) and 30–34 (−0.2 per 

year, 95% CI: −0.3 – −0.1, p = 0.002; see Figure 11). Predicted 

MMRs did not change significantly for women aged 25–29 

(−0.1 per year, 95% CI: −0.2–0.0, p = 0.057; see Figure 10) 

or 35–39 (−0.1 per year, 95% CI: −0.3–0.1, p = 0.425; see 

Figure 12) and increased for women aged 40 and over (2.5, 

95% CI: 1.8–3.3, p < 0.001; see Figure 13). Assuming that 

all states had adopted the checkbox, trends were similar, 

declining for women aged 20–24 (−0.2 per year, 95% CI: 

−0.4 – −0.1, p = 0.008) and 30–34 (−0.3 per year, 95% CI: 

−0.5 – −0.1, p = 0.013). Predicted MMRs assuming that all 

states had adopted the checkbox did not change significantly 

for women aged 25–29 (−0.1 per year, 95% CI: −0.3–0.0, 

p = 0.116) and 35–39 (−0.1 per year, 95% CI: −0.5–0.3, 

p = 0.552) but increased for women aged 40 and over (7.7, 

95% CI: 6.1–9.4, p < 0.001). 

By race and Hispanic origin, predicted MMRs increased 

for non-Hispanic white women by 0.1 per year from 1999 

through 2017 (95% CI: 0.1–0.2, p < 0.001) assuming no 

checkbox, and by 0.3 per year (95% CI: 0.2–0.5, p < 0.001) 

assuming all states had adopted the checkbox (Table 2; 

Figure 14). Trends declined for non-Hispanic black women, 

assuming that no states had adopted the checkbox (−0.3, 

95% CI: −0.6 – −0.1, p = 0.004). Assuming that all states 

had adopted the checkbox, predicted MMRs among nonHispanic black women declined by −0.4 per year (95% CI: 

−0.9–0.0), but this trend was not statistically significant 

(p = 0.072). 

Figure 6. Observed and predicted maternal mortality rates: United States, 1999–2017 

Series 3, Number 44 9 NATIONAL CENTER FOR HEALTH STATISTICS 
1Observed rates suppressed when the number of deaths is fewer than 20 (in 2000).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

1Observed rates suppressed when the number of deaths is fewer than 20 (all years).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

10

Figure 7. Observed and predicted maternal mortality rates among females under age 15: United States, 1999–2017 

Figure 8. Observed and predicted maternal mortality rates among females aged 15–19: United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 10 Series 3, Number 44
 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these fac!Drs and year as well as revision status. 

SOURCE: NCHS, National Vital statistics SyslBm. 

NOTE: Models were adjusted for age group, race and Hispanic origin, and stalB of occurrence, and Included Interactions between these factors and year as Mii as revision status. 

SOURCE: NCHS, National Vrtal Statistics System. 

Figure 9. Observed and predicted maternal mortality rates among women aged 20–24: United States, 1999–2017 

Figure 10. Observed and predicted maternal mortality rates among women aged 25–29: United States, 1999–2017 

Series 3, Number 44 11 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models ware adjusted for age gn:JUp, race and Hispanic ortgln, and state cf occurrence, and Included lnteracUons between these factors end year as wall as revision status. 

SOURCE: NCHS, National Vital Statistics System. 

NOTE: Models were adjusted for age group, race and Hispanic origin, and state af occurrence, and included interactions behveen these factors and year as well as revision status. 

SOURCE: NCHS, NaUonal Vltal StaUstlcs System. 

Figure 11. Observed and predicted maternal mortality rates among women aged 30–34: United States, 

1999–2017 

Figure 12. Observed and predicted maternal mortality rates among women aged 35–39: United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 12 Series 3, Number 44 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjuslBd fer age group, race and Hispanic origin, and state of occum1nce, and Included lnteracUons between these facb:lrs and year as well as revision status. 

SOURCE: NCHS, National Vital Statistics System. 

Figure 13. Observed and predicted maternal mortality rates among women aged 40 and over: United States, 

1999–2017
 

Among Hispanic women, predicted MMRs declined over 

time, both assuming no checkbox (–0.3, 95% CI: –0.3 – –0.2, 

p < 0.001) and assuming that all states had adopted the 

checkbox (–0.4, 95% CI: –0.6 – –0.2, p < 0.001). Trends 

among non-Hispanic women of other races did not change 

significantly with the checkbox (–0.2, 95% CI: –0.4–0.1, 

p = 0.280) or without (–0.1, 95% CI: –0.3–0.0, p = 0.104). 

Causes of maternal death 

The impact of the checkbox varied by maternal cause of 

death (Table 3). Cause-specific MMRs increased by less than 

0.5 deaths per 100,000 live births because of the checkbox 

for the following causes (or groups of causes): pregnancy 

with abortive outcomes (O00–O07); edema, proteinuria 

and hypertensive disorders in pregnancy, childbirth and 

the puerperium (O10–O16); liver disorders in pregnancy, 

childbirth and the puerperium (O26.6); maternal care 

related to the fetus and amniotic cavity and possible delivery 

problems (O30–O48); complications of labor and delivery 

(O60–O75); complications predominantly related to the 

puerperium (O85–O92); mental disorders and diseases of the 

nervous system complicating pregnancy, childbirth and the 

puerperium (O99.3); and diseases of the respiratory system 

complicating pregnancy, childbirth and the puerperium 

(O99.5). 

The impact of the checkbox was largest for indirect or 

nonspecific causes of death. Maternal deaths due to other 

obstetric conditions not elsewhere classified (O95–O99) 

increased by 8.3 (95% CI: 7.6–9.0) as a result of the checkbox, 

and nonspecific causes (O26.8, O95, O99.8) increased by 

5.6 (95% CI: 5.1–6.1). While MMRs for direct causes (26)

increased by 5.2 (95% CI: 4.4–6.1) as a result of the checkbox, 

the impact was driven by the inclusion of a nonspecific cause 

of death in this category, other specified pregnancy-related 

conditions (O26.8). Late maternal MMRs increased by 3.5 

(95% CI: 3.1–3.9) as a result of the checkbox. 

Trends in predicted MMRs both with and without the 

checkbox varied by cause of death (Table 4; Figures I–XXIII). 

Predicted MMRs declined significantly from 1999 through 

2017 under both scenarios for the following causes of 

maternal death: direct causes (26) (excluding O26.8, other 

specified pregnancy-related conditions); pregnancy with 

abortive outcomes (O00–O07); edema, proteinuria and 

hypertensive disorders in pregnancy, childbirth and the 

puerperium (O10–O16); complications of labor and delivery 

(O60–O75); and complications predominantly related to the 

puerperium (O85–O92). Predicted MMRs increased under 

both scenarios for the following causes: other maternal 

disorders predominantly related to pregnancy (O20–O29), 

which was driven by the inclusion of other specified 

pregnancy-related conditions (O26.8) in this group; indirect 

causes (26); late maternal deaths (O96–O97); and the group 

of nonspecific causes (O26.8, O95, O99.8). 

Series 3, Number 44 13 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status. 

SOURCE: NCHS, National Vital Statistics System. 

Figure 14. Observed and predicted maternal mortality rates, by race and Hispanic origin: United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 14 Series 3, Number 44 
NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Dotted lines represent matemal mortality rates (MMRs) adjustsd for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were 

adjuslBd for age group, race and Hispanic origin, and stets of occurrence, and included interactions between these faclDni and year as well as revision status. 

SOURCE: NCHS, Natlonal Vital statistics System. 

NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

15

The Impact of Potential Misclassification 

of Pregnancy Status on the Death 

Certificate on MMR Trends From 1999 

Through 2017 

Accounting for a certain percentage of death 

certificates where a pregnancy checkbox may 

have been selected in error 

Several sensitivity analyses were conducted to examine 

trends in MMRs over time by subgroup and cause of death, 

and to explore the impact of potential misclassification. 

Analyses accounting for varied percentages of false positives 

(0.25%, 0.50%, 1.00%), resulted in lower predicted MMRs 

from 1999 through 2017 (assuming that all states adopted 

the checkbox in 1999; see Figures 15–17). 

The impact of the adjustment for this false-positive rate was 

larger for older age groups and non-Hispanic black and white 

women (Figures XXIV–XXX). 

Adjusting for outcome misclassification 

Results of analyses examining the impact of misclassification 

can be found in Table V and in the data visualization 

tool (available from: https://www.cdc.gov/nchs/maternalmortality/dashboard/). For example, assuming that the 

values for Se before and after the implementation of 

the checkbox were 0.60 and 0.80, respectively, and the 

proportion of records that were false positives was 0.10 

and 0.35, respectively, before and after the checkbox, the 

estimated MMRs in 2017 converged to 19.1–19.2 maternal 

deaths per 100,000 live births (the observed MMR was 

21.6). These values for Se and proportion of false positives 

are within the range of previously published estimates 

(8,9,11,13,17–24,33–35, 38). 

Examining the predicted MMRs for women aged 40 and 

over and using the same values described previously, 

except increasing the proportion of false positives after the 

checkbox implementation to 0.6 (consistent with the greater 

degree of misclassification among this age group [17]), the 

predicted MMRs in 2017 were 133.9 assuming that no states 

had adopted the checkbox and 121.4 assuming that all states 

had adopted the checkbox (compared with an observed 

MMR of 186.1 deaths per 100,000 live births). 

Falsification test: Nonmaternal causes death 

Finally, as a falsification test, models were run examining the 

impact of the pregnancy checkbox on several nonmaternal 

causes of death both among female decedents of 

reproductive age (15–44) and female decedents to whom 

the pregnancy checkbox does not apply (under age 10 and 

55–59). The percentage of deaths among female decedents 

aged 15–44 that were due to unintentional injury, suicide, 

drug overdose, homicide, or unknown or ill-specified causes 

declined with the implementation of the pregnancy 

Figure 15. Observed and predicted maternal mortality rates, adjusted for an error rate of 0.25% in the pregnancy 

checkbox: United States, 1999–2017 

Series 3, Number 44 15 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Dotted lines represent matemal mortality rates (MMRs) adjusted forflxed error rates, whlle solld llnea depict the orlglnal predicted and observed MMRa. Models were 

adjus1Bd for age group, raoe and Hispanic origin, and stats of occurrence, and included interec:tions between these factora and year as well as revision status. 

SOURCE: NCHS, NaUonal Vita.I SlaUsUca Sys1Bm. 

NOTES: Dotted lines represent matemal mortality rates (MMRs) adjus1Bd for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were 

adjusted for age group, race and Hispanic origin, and stats of occurrence, and included interec:tions between these factora and year as well as revision status. 

SOURCE: NCHS, National Vital Statistics $ys1Bm. 

Figure 16. Observed and predicted maternal mortality rates, adjusted for an error rate of 0.50% in the pregnancy 

checkbox: United States, 1999–2017 

Figure 17. Observed and predicted maternal mortality rates, adjusted for an error rate of 1.00% in the pregnancy 

checkbox: United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 16 Series 3, Number 44 
checkbox by 0.53% (95% CI: –0.85 – –0.20, p = 0.001) (Table 

5). In contrast, there was an increase in the percentage of 

deaths due to these same causes among female decedents 

under age 10 or 55–59 (0.21, 95% CI: 0.03–0.39, p = 0.02). 

These results suggest that a small percentage of deaths due 

to nonmaternal causes, such as unintentional injury, may be 

coded as maternal deaths due to the checkbox. 

Discussion 

This report examined the impact of the implementation of 

the 2003 revision of the U.S. Standard Certificate of Death 

on MMRs in the United States and related trends from 1999 

through 2017. Results suggest that the implementation of 

the revised standard certificate, which included a question 

to determine pregnancy status (the pregnancy checkbox), 

was associated with an increased identification of maternal 

deaths. Averaging over the period 2003–2017, the checkbox 

resulted in an MMR increase of 9.6 deaths per 100,000 live 

births (95% CI: 8.6–10.6). 

Impact of the Checkbox 

The impact of the checkbox on MMRs was larger among 

older age groups, particularly ages 40 and over. A 

companion report that calculated maternal mortality rates 

for 2015–2016 with and without considering the pregnancy 

checkbox also found that the impact of the checkbox was 

largest for older age groups. In general, the MMRs in that 

report that did not consider the pregnancy checkbox (based 

only on information in the literal text) were similar to the 

estimated MMRs in this report, assuming that no states 

had adopted the checkbox. However, the estimated MMRs 

assuming that no states had adopted the checkbox tended 

to be somewhat higher than the MMRs reported in Hoyert 

et al. (e.g., predicted MMRs for 2015 and 2016 were 11.7 

and 12.2, respectively, compared with 8.7 in Hoyert et al. 

[15]), with larger discrepancies among women aged 40 and 

over (e.g., predicted MMRs for 2015 and 2016 were 77.5 and 

82.6, respectively, compared with 30.6 and 31.1 in Hoyert et 

al.). These reports used different methodologies to evaluate 

the impact of the checkbox. One potential reason for 

discrepancies may be that with the addition of the checkbox, 

certifiers may be less likely to record pregnancy-related 

information in the literal text fields. Consequently, recoding 

death records without considering the checkbox may result 

in lower MMRs than would have been identified had the 

checkbox never been implemented. 

Prior studies have suggested that the pregnancy checkbox 

had a larger impact on MMRs among older women, likely 

resulting in overestimates (17). However, other studies have 

suggested that the degree to which maternal deaths were 

undercounted prior to the implementation of the checkbox 

was larger for older women and teenagers. For example, 

a study in Maryland using data from 1993 through 2000 

suggested that 58% of maternal deaths among women 

aged 40 and over and 50% among women under age 20 

were not reported on the death certificate, in contrast to 

38% among all women (11). A study of Texas data after the 

implementation of the checkbox suggested that there were 

higher proportions of false positives and false negatives 

among women over 35 compared with women under 25 

(24). While these estimates are based on only two states 

and not generalizable to the entire United States, it suggests 

that among the oldest and youngest age groups, maternal 

deaths may have been disproportionately underestimated 

prior to the implementation of the checkbox, which could 

partly explain the larger impact of the checkbox seen 

among these age groups in this report. Additionally, prior 

studies indicate that there is likely a greater percentage of 

false positives among older women due to the pregnancy 

checkbox, inflating MMRs among older ages (4,17,24,37). 

Thus, part of the increase seen due to the implementation 

of the checkbox may be related to these false positives. 

Differences by race and Hispanic origin also were seen in 

the impact of the checkbox. The impact was smallest for 

Hispanic women and largest for non-Hispanic black women. 

It is unclear whether maternal deaths among non-Hispanic 

black women were disproportionately missed prior to 

the implementation of the checkbox, whether there is a 

greater number of false positives among this group after the 

adoption of the revised standard certificate, or both. Some 

evidence suggests that false positives are more likely among 

non-Hispanic black women compared with non-Hispanic 

white women (37). 

Consistent with prior reports, the impact of the checkbox on 

MMRs was greatest for nonspecific causes of maternal death 

(4,13,15), including maternal deaths due to other obstetric 

conditions not elsewhere classified (O95–O99), and a group 

of nonspecific causes of maternal death (O26.8, O95, O99.8). 

These causes of death are more likely the ones for which the 

checkbox may be the only indication of a current or recent 

pregnancy and where errors in the pregnancy checkbox 

would have the greatest impact, inflating MMRs related to 

these causes. Consequently, errors in the application of the 

checkbox (indicating a current or recent pregnancy when 

that is not the case) may lead to deaths due to cancer or 

infectious disease, for example, being coded to a maternal 

cause of death. A companion report that examined MMRs 

during 2015–2016 without considering the checkbox 

information found that heart conditions and cancer were 

the causes of death most frequently identified when death 

certificates were re-coded without considering the pregnancy 

checkbox. Because these causes of death are more common 

with increasing age, errors in the application of the checkbox 

have a disproportionate impact on MMRs among older 

women. Additionally, deaths due to nonmaternal causes 

of such as unintentional injury may erroneously receive 

one of these nonspecific codes if the pregnancy checkbox 

indicates a current or recent pregnancy, depending upon 

what information appears in part 1 or part 2 of the death 

certificate (15,39,40). 

Series 3, Number 44 17 NATIONAL CENTER FOR HEALTH STATISTICS 
Trends 

Maternal mortality rates were predicted under two 

alternative scenarios: (1) assuming that no states adopted 

the checkbox and (2) assuming that all states implemented 

the checkbox throughout the entire period. Under both 

scenarios, predicted MMRs did not change significantly from 

1999 through 2017 (–0.03, 95% CI: –0.09–0.03; and 0.04, 

95% CI: –0.07–0.15, respectively) after adjustment for age, 

race and Hispanic origin, and state. In a companion report, 

MMRs during 2015–2016 without considering the pregnancy 

checkbox were similar to those for 2000–2001, suggesting 

that in the absence of the checkbox, MMRs would not have 

increased over that time period. However, results presented 

here suggest differences in the estimated trends by subgroup 

and by cause of death. Predicted MMRs declined from 1999 

through 2017 for non-Hispanic black women, Hispanic 

women, and women aged 20–24 and 30–34. Consistent 

with previous studies (4), predicted MMRs increased for 

non-Hispanic white women and women aged 40 and over. 

Importantly, this analysis cannot determine what the true 

change was in maternal mortality over this time period, as 

it is unclear how much of the impact of the checkbox was 

due to better identification of true maternal deaths and how 

much was potentially due to an increase in false positives. 

Consistent with prior studies (4,15,16), there were 

differences by cause of death in estimated trends. Predicted 

MMRs declined for several direct causes of maternal death, 

including pregnancy with abortive outcomes (O00–O07); 

edema, proteinuria, and hypertensive disorders in pregnancy, 

childbirth and the puerperium (O10–O16); complications 

of labor and delivery (O60–O75); and complications 

predominantly related to the puerperium (O85–O92). 

Among all direct causes, excluding the nonspecific code 

O26.8, predicted MMRs declined by 0.17 each year (95% 

CI: –0.10– –0.01) assuming no checkbox and by 0.22 (95% 

CI: –0.30– –0.15) assuming that all states had adopted the 

checkbox. Conversely, predicted MMRs increased for several 

indirect and nonspecific causes of maternal death, including 

other specified pregnancy-related conditions (O26.8); late 

maternal deaths (O96–O97); and the group of nonspecific 

causes (O26.8, O95, O99.8). It is unclear to what extent 

these increases may be a consequence of nonmaternal 

deaths (e.g., deaths due to drug overdose or unintentional 

injury) being assigned one of these nonspecific or indirect 

cause-of-death codes due to the pregnancy checkbox being 

selected, possibly in error. The falsification tests suggested 

that the percentage of all deaths among reproductive-age 

women due to unintentional injuries, suicide, homicide, 

drug overdose, or unknown or ill-defined causes declined 

with the implementation of the checkbox. Small increases 

were observed among women for whom the pregnancy 

checkbox does not apply (under age 10 or 55–59), largely 

driven by increases in drug overdose deaths. This would 

suggest that a small percentage of nonmaternal deaths may 

be misclassified as maternal among women of reproductive 

age. 

Misclassification 

Based on prior research, death certificate data may both 

over- and underestimate maternal or pregnancy-associated 

deaths. Results presented in this report describe how MMRs 

may vary across a range of plausible values for Se and PVP. 

Studies that have conducted data linkages to evaluate the 

validity of the death certificate data in capturing maternal 

or pregnancy-associated deaths before the 2003 revision 

have suggested that as many as 40%–70% of pregnancies 

among decedents were historically not captured by death 

certificate data (8,12,22,34,36). Similar studies conducted 

after the implementation of the checkbox have found that 

many maternal deaths have no evidence of current or recent 

pregnancy and that many current or recent pregnancies 

are not captured, with Se values (the proportion of true 

pregnancies among female decedents identified using 

death certificate data) ranging from 0.48 to 0.84 (13,17–24, 

33–35), and PVP values (the proportion of maternal deaths 

where a current or recent pregnancy is identified) ranging 

from 0.32 to 1.00 (20,24,41). While national estimates of Se 

and PVP for identifying maternal deaths in death certificate 

data are not available, results from a recent study of four 

states suggest that Se (0.62) is slightly lower than PVP (0.68) 

(37). If these values are similar across the United States, 

then overall MMRs may be slightly underestimated, with 

the number of false positives smaller than the number of 

false negatives. One potential limitation of these types of 

linkage studies is the lack of information on pregnancies that 

have not been documented in electronic medical records, or 

resulted in a live birth or fetal death, which would tend to 

deflate PVP values. 

The degree of misclassification likely varies by many factors, 

including age, race and Hispanic origin, state, and cause 

of death. Because maternal deaths are a rare event, few 

studies have provided estimates of Se and PVP by subgroup. 

A study of Texas data after the implementation of the 

checkbox suggested that Se and PVP values were lower for 

women over age 35 than for women under 25 (24). There 

were also differences by racial and ethnic group, with a 

smaller proportion of false negatives among non-Hispanic 

black and Hispanic women, and a higher proportion of 

false positives among non-Hispanic black and non-Hispanic 

white women (24). However, severe data quality issues in 

that state (23,24,42) preclude those findings from being 

generalized to the United States. Other studies have also 

suggested that false positives are more likely among older 

age groups compared with younger age groups and among 

non-Hispanic black women compared with non-Hispanic 

white women (37). Future studies providing more detail on 

Se and PVP by demographic subgroup across a wider array of 

states could facilitate a better understanding of the accuracy 

of MMRs and inform analyses adjusting for misclassification 

differentially by age, race and Hispanic origin, and other 

factors. 

NATIONAL CENTER FOR HEALTH STATISTICS 18 Series 3, Number 44 
This analysis has several limitations. West Virginia did not 

adopt the revised standard certificate until mid-2017. 

Thus, estimates of the impact of the revision for West 

Virginia will be understated. California uses a question 

that is inconsistent with the 2003 standard certificate; 

it asks about pregnancy status in the past 12 months. 

Consequently, maternal deaths (during pregnancy or within 

42 days) are likely underestimated in California, while late 

maternal deaths (pregnant within 43 days to 1 year) may 

be overstated given that checkbox-only deaths are coded to 

the late maternal category. Maryland, which was the only 

state to show a decline in MMRs with the implementation 

of the revised certificate, had a question prior to the revision 

that asked about pregnancy in the past year along with the 

corresponding date of delivery. It is possible that the decline 

in MMRs with the implementation of the revised standard 

certificate in Maryland is due to efforts in that state to 

identify maternal or pregnancy-associated deaths through 

data linkages and record reviews prior to implementing 

the revision. It is also possible that this decrease was due 

to chance, and no adjustments were made for multiple 

comparisons in this analysis. Because many states had 

some type of question about pregnancy status on the death 

certificate prior to the 2003 revision, the predicted MMRs 

assuming that no states had adopted the checkbox may be 

overestimated, as some of these states did have a pregnancy 

question prior to the revision. 

Analyses adjusting for various error rates in the application 

of the checkbox on the death certificates only account for 

potential false positives, resulting in a likely underestimation 

of MMRs, as death certificate data often fail to capture 

many true maternal deaths. These analyses also assumed a 

constant error rate over time, which may not be accurate; 

they were based on error rates among women outside of 

reproductive age, which may not be comparable with the 

error rates among reproductive-age women. Adjustments 

for outcome misclassification, which account for both overand underreporting of maternal deaths, likely provide better 

estimates of MMR values and trends. However, the true 

values for Se and PVP for the United States (and by subgroup 

or cause of death) are unknown, and thus these analyses 

are largely exploratory. It remains unknown to what extent 

the implementation of the pregnancy checkbox resulted in 

better ascertainment of maternal deaths (i.e., reductions 

in false negatives) and to what extent the checkbox may 

have increased false positives. Other data sources provide 

information about maternal or pregnancy-related mortality, 

such as the Pregnancy Mortality Surveillance System (6), data 

from maternal mortality review committees (20), and statebased quality-assurance projects (37). These data sources, 

which rely on detailed record reviews or data linkages to verify 

recent pregnancy status, may not be subject to the same 

degree of misclassification as vital records data. Finally, there 

may have been other factors that changed simultaneously 

when states revised their death certificates, confounding the 

estimated impact of the checkbox. Specifically, the adoption 

of electronic death registration systems, the implementation 

of various quality-assurance processes (e.g., data linkages 

with birth and fetal death records), and the centralization 

of coding cause of death at NCHS. While an indicator for 

when coding was completely centralized (in 2011) was 

included in the models, many states had already relied on 

NCHS to code cause-of-death information prior to 2011. 

Specific information regarding what years various states 

were responsible for cause-of-death coding prior to 2011 is 

not available. State-specific estimates of the impact of the 

checkbox may be confounded by unmeasured factors that 

changed at the time of the revision, such as severe influenza 

seasons (43), rapid increases in drug overdose mortality (44), 

or loss of hospital-based obstetric services (45), among other 

potential factors. While higher-order trends (i.e., quadratic) 

were not apparent at the national level, it is possible that 

trends in MMRs in specific states before or after the revision 

were nonlinear, which could have biased estimated statelevel impacts of the checkbox. 

Conclusions 

This report examines the impact of the staggered adoption 

of the 2003 revision of the standard death certificate on 

trends in maternal mortality in the United States from 1999 

through 2017. Results suggest that the observed increases 

in MMRs during this time period were largely due to the 

staggered implementation of the checkbox, which increased 

identification of maternal deaths. Averaging over the period 

2003–2017, the checkbox resulted in an MMR increase of 9.6 

deaths per 100,000 live births (95% CI: 8.6–10.6). Estimated 

trends accounting for the implementation of the checkbox 

indicated that there were no significant changes in MMRs 

over time, although trends varied by maternal age, race and 

Hispanic origin, and cause of maternal death. Additionally, 

the misclassification of pregnancy status on the death 

certificate likely contributed to increasing trends among 

women aged 40 and over and among nonspecific causes of 

maternal death. 

References 

1.	 Global Burden of Disease Maternal Mortality 

Collaborators. Global, regional, and national levels of 

maternal mortality, 1990–2015: A systematic analysis 

for the Global Burden of Disease Study 2015. Lancet 

388(10053):1775–812. 2016. 

2.	 Hunt PH, Bueno de Mesquita J. Reducing maternal 

mortality: The contribution of the right to the highest 

attainable standard of health. 2010. 

3.	 World Health Organization. Trends in maternal 

mortality: 1990 to 2015: Estimates by WHO, UNICEF, 

UNFPA, The World Bank Group and the United Nations 

Population Division. 2015. 

Series 3, Number 44	 19 NATIONAL CENTER FOR HEALTH STATISTICS 
4.	 MacDorman MF, Declercq E, Thoma ME. Trends 

in maternal mortality by sociodemographic 

characteristics and cause of death in 27 states and the 

District of Columbia. Obstet Gynecol 129(5):811–8. 

2017. 

5.	 Neggers YH. Trends in maternal mortality in the United 

States. Reprod Toxicol 64:72–6. 2016. 

6.	 Petersen EE, Davis NL, Goodman D, Cox S, Mayes 

N, Johnston E, et al. Vital signs: Pregnancy-related 

deaths, United States, 2011–2015, and strategies 

for prevention, 13 states, 2013–2017. MMWR Morb 

Mortal Wkly Rep 68(18):423–9. 2019. 

7.	 Petersen EE, Davis NL, Goodman D, Cox S, Syverson C, 

Seed K, et al. Racial/ethnic disparities in pregnancyrelated deaths—United States, 2007–2016. MMWR 

Morb Mortal Wkly Rep 68(35):762–5. 2019. 

8.	 Horon IL, Cheng D. Effectiveness of pregnancy check 

boxes on death certificates in identifying pregnancyassociated mortality. Public Health Rep 126(2):195– 

200. 2011. 

9.	 MacKay AP, Berg CJ, Duran C, Chang J, Rosenberg H. 

An assessment of pregnancy-related mortality in the 

United States. Paediatr Perinat Epidemiol 19(3):206– 

14. 2005. 

10.	 Hoyert DL, Danel I, Tully P. Maternal mortality, United 

States and Canada, 1982–1997. Birth 27(1):4–11. 

2000. 

11.	 Horon IL. Underreporting of maternal deaths on death 

certificates and the magnitude of the problem of 

maternal mortality. Am J Public Health 95(3):478–82. 

2005. 

12.	 Horon IL, Cheng D. Enhanced surveillance for 

pregnancy-associated mortality—Maryland, 1993– 

1998. JAMA 285(11):1455–9. 2001. 

13.	 Creanga AA. Maternal mortality in the United States: A 

review of contemporary data and their limitations. Clin 

Obstet Gynecol 61(2):296–306. 2018. 

14.	 MacDorman MF, Declercq E, Cabral H, Morton C. 

Recent increases in the U.S. maternal mortality rate: 

Disentangling trends from measurement issues. Obstet 

Gynecol 128(3):447–55. 2016. 

15.	 Hoyert DL, Uddin SFG, Miniño AM. Maternal mortality 

evaluation: Impact of the inclusion of a pregnancy 

status checkbox item on death certificates. National 

Vital Statistics Reports; vol 69 no 2. Hyattsville, MD: 

National Center for Health Statistics. 2019. 

16.	 Joseph KS, Lisonkova S, Muraca GM, Razaz N, Sabr Y, 

Mehrabadi A, Schisterman EF. Factors underlying the 

temporal increase in maternal mortality in the United 

States. Obstet Gynecol 129(1):91–100. 2017. 

17.	 Davis NL, Hoyert DL, Goodman DA, Hirai AH, Callaghan 

WM. Contribution of maternal age and pregnancy 

checkbox on maternal mortality ratios in the United 

States, 1978–2012. Am J Obstet Gynecol 217(3):352. 

e1–7. 2017. 

18.	 Nelson DB, Moniz MH, Davis MM. Populationlevel factors associated with maternal mortality in 

the United States, 1997–2012. BMC Public Health 

18(1):1007. 2018. 

19.	 Daymude AEC, Catalano A, Goodman D. Checking the 

pregnancy checkbox: Evaluation of a four-state quality 

assurance pilot. Birth 46(4):648–55. 2019. 

20.	 Building U.S. Capacity to Review and Prevent Maternal 

Deaths Project Team. Report from nine maternal 

mortality review committees. 2018. 

21.	 St Pierre A, Zaharatos J, Goodman D, Callaghan WM. 

Challenges and opportunities in identifying, reviewing, 

and preventing maternal deaths. Obstet Gynecol 

131(1):138–42. 2018. 

22.	 Mitchell C, Lawton E, Morton C, McCain C, Holtby S, 

Main E. California pregnancy-associated mortality 

review: Mixed methods approach for improved case 

identification, cause of death analyses and translation 

of findings. Matern Child Health J 18(3):518–26. 2014. 

23.	 MacDorman MF, Declercq E, Thoma ME. Trends in 

Texas maternal mortality by maternal age, race/ 

ethnicity, and cause of death, 2006–2015. Birth 

45(2):169–77. 2018. 

24.	 Baeva S, Saxton DL, Ruggiero K, Kormondy ML, Hollier 

LM, Hellerstedt J, et al. Identifying maternal deaths 

in Texas using an enhanced method, 2012. Obstet 

Gynecol 131(5):762–9. 2018. 

25.	 National Center for Health Statistics. National Vital 

Statistics System: Birth data. Available from: 

https://www.cdc.gov/nchs/nvss/births.htm. 

26.	 Say L, Chou D, Gemmill A, Tunçalp Ö, Moller AB, 

Daniels J, et al. Global causes of maternal death: 

A WHO systematic analysis. Lancet Glob Health 

2(6):e323–33. 2014. 

27.	 Oldenburg CE, Moscoe E, Bärnighausen T. Regression 

discontinuity for causal effect estimation in 

epidemiology. Curr Epidemiol Rep 3:233–41. 2016. 

28.	 Bor J, Moscoe E, Mutevedzi P, Newell ML, 

Bärnighausen T. Regression discontinuity designs in 

epidemiology: Causal inference without randomized 

trials. Epidemiology 25(5):729–37. 2014. 

29.	 Moscoe E, Bor J, Bärnighausen T. Regression 

discontinuity designs are underutilized in medicine, 

epidemiology, and public health: A review of current 

and best practice. J Clin Epidemiol 68(2):122–33. 2015. 

NATIONAL CENTER FOR HEALTH STATISTICS 20	 Series 3, Number 44 
30.	 Ventura SJ. The U.S. National Vital Statistics System: 

transitioning into the 21st century, 1990–2017. 

National Center for Health Statistics. Vital Health Stat 

1(62). 2018. 

31.	 Lash TL, Fox MP, Fink AK. Applying quantitative bias 

analysis to epidemiologic data. In: Gail M, Samet JM, 

Tsiatis A, Wong W, editors. Statistics for biology and 

health. New York, NY: Springer. 2009. 

32.	 Rothman KJ, Greenland S, Lash TL. Modern 

epidemiology. 3rd ed. Philadelphia, PA: Lippincott 

Williams & Wilkins. 2008. 

33.	 Saucedo M, Bouvier-Colle MH, Chantry AA, LamarcheVadel A, Rey G, Deneux-Tharaux C. Pitfalls of national 

routine death statistics for maternal mortality study. 

Paediatr Perinat Epidemiol 28(6):479–88. 2014. 

34.	 Tran T, Roberson E, Borstell J, Hoyert DL. Evaluation 

of pregnancy mortality in Louisiana using enhanced 

linkage and different indicators defined by WHO and 

CDC/ACOG: Challenging and practical issues. Matern 

Child Health J 15(7):955–63. 2011. 

35.	 Tennessee Department of Health. Tennessee maternal 

mortality: Review of 2017 maternal deaths. 2017. 

36.	 California Department of Public Health. The California 

pregnancy-associated mortality review: Report from 

2002 to 2007 maternal death reviews. 2018. 

37.	 Catalano A, Davis NL, Petersen EE, Harrison C, Kieltyka 

L, You M, et al. Pregnant? Validity of the pregnancy 

checkbox on death certificates in four states, and 

characteristics associated with pregnancy checkbox 

errors. Am J Obstet Gynecol. S0002–9378(19)31222–0. 

2019. 

38.	 Deneux-Tharaux C, Berg C, Bouvier-Colle MH, Gissler 

M, Harper M, Nannini A, et al. Underreporting of 

pregnancy-related mortality in the United States and 

Europe. Obstet Gynecol 106(4):684–92. 2005. 

39.	 National Center for Health Statistics. Instructions for 

classifying underlying and multiple causes of death, 

ICD–10. 2017. 

40.	 Anderson RN. Maternal deaths in the National 

Vital Statistics System. In: 2019 Proceedings of the 

National Center for Health Statistics Board of Scientific 

Counselors. Hyattsville, MD: National Center for Health 

Statistics. 2019. 

41.	 Building U.S. Capacity to Review and Prevent Maternal 

Deaths Project Team. Report from maternal mortality 

review committees: A view into their critical role. 

2017. 

42.	 Koch AR, Lightner S, Geller SE. Identifying maternal 

deaths in Texas using an enhanced method, 2012. 

Obstet Gynecol 132(2):520–1. 2018. 

43.	 Callaghan WM, Creanga AA, Jamieson DJ. Pregnancyrelated mortality resulting from influenza in the 

United States during the 2009–2010 pandemic. Obstet 

Gynecol 126(3):486–90. 2015. 

44.	 Goldman-Mellor S, Margerison CE. Maternal drugrelated death and suicide are leading causes of 

post-partum death in California. Am J Obstet Gynecol 

221(15):489.e1–9. 2019. 

45.	 Kozhimannil KB, Hung P, Henning-Smith C, Casey MM, 

Prasad S. Association between loss of hospital-based 

obstetric services and birth outcomes in rural counties 

in the United States. JAMA 319(12):1239–47. 2018. 

Series 3, Number 44	 21 NATIONAL CENTER FOR HEALTH STATISTICS 
Table 1. Average change in maternal mortality rates associated with 

the pregnancy checkbox implementation, by age and race and Hispanic 

origin: United States, 2003–2017 

Characteristic Change in maternal mortality rate (95% CI) 

Overall 9.6 (8.6 – 10.6) 

Age group 

Under 15 

15–19 

20–24 

25–29 

30–34 

35–39 

40 and over 

14.5 (–10.3 – 39.3) 

3.7 (1.7 – 5.7) 

5.6 (4.1 – 7.1) 

5.4 (3.8 – 7.1) 

6.0 (3.9 – 8.0) 

13.9 (9.7 – 18.0) 

145.3 (127.6 – 163.1) 

Race and Hispanic origin 

Non-Hispanic white 

Non-Hispanic black 

Non-Hispanic other 

Hispanic 

8.6 (7.5 – 9.7) 

19.6 (15.3 – 24.0) 

7.1 (4.2 – 10.0) 

6.2 (4.3 – 8.1) 

Prerevision pregnancy question 

No 

Yes 

9.8 (8.7 – 10.9) 

8.1 (6.8 – 9.4) 

Centralized cause-of-death coding 

No (before 2011) 

Yes (2011–2017)

9.0 (8.0 – 10.0) 

10.9 (9.5 – 12.2) 

NOTE: CI is confidence interval.
 

SOURCE: NCHS, National Vital Statistics System, 1999–2017.
 

NATIONAL CENTER FOR HEALTH STATISTICS 22 Series 3, Number 44 
Table 2. Trends in predicted maternal mortality rates, by age and race and Hispanic origin: United States, 

1999–2017 

Average annual change in maternal mortality rate 

Characteristic No checkbox (95% CI) p All checkbox (95% CI) p

Overall 0.0 (–0.1 – 0.0) 0.307 0.0 (– 0.1 – 0.2) 0.459 

Age group 

Under 15 

15–19 

20–24

25–29

30–34

35–39

40 and over 

0.4 (–0.8 – 1.5) 

0.0 (–0.1 – 0.1) 

– 0.1 (–0.2 – 0.0) 

– 0.1 (– 0.2 – 0.0) 

– 0.2 (– 0.3 – –0.1) 

– 0.1 (– 0.3 – 0.1) 

2.5 (1.8 – 3.3) 

0.519 

0.616 

0.001 

0.057

0.002

0.425

Less than 0.001 

1.7 (–1.9 – 5.3) 

0.1 (–0.1 – 0.3) 

–0.2 (–0.4 – –0.1) 

– 0.1 (–0.3 – 0.0) 

– 0.3 (–0.5 – –0.1) 

– 0.1 (–0.5 – 0.3) 

7.7 (6.1 – 9.4) 

0.359 

0.538 

0.008 

0.116 

0.013 

0.552 

Less than 0.001 

Race and Hispanic origin 

Non-Hispanic white 

Non-Hispanic black

Non-Hispanic other

Hispanic

0.1 (0.1 – 0.2) 

– 0.3 (– 0.6 – –0.1) 

– 0.1 (– 0.3 – 0.0) 

– 0.3 (– 0.3 – –0.2) 

Less than 0.001 

0.004

0.104

Less than 0.001

0.3 (0.2 – 0.5) 

– 0.4 (–0.9 – 0.0) 

– 0.2 (–0.4 – 0.1) 

– 0.4 (–0.6 – –0.2) 

Less than 0.001 

0.072 

0.280 

Less than 0.001 

NOTE: CI is confidence interval.
 

SOURCE: NCHS, National Vital Statistics System, 1999–2017.
 

Series 3, Number 44 23 NATIONAL CENTER FOR HEALTH STATISTICS 
Table 3. Estimated impact of the pregnancy checkbox on cause-specific maternal mortality rates: United States, 

2003–2017 

Average change in maternal 

Cause of maternal death mortality rate (95% CI) 

Direct causes 5.2 (4.4 – 6.1) 

Direct causes excluding O26.8 2.0 (1.3 – 2.7) 

Alternative grouping of direct causes (A34,O00–O92) 4.8 (4.0 – 5.6) 

Alternative grouping of direct causes (A34,O00–O95) 5.6 (4.8 – 6.5) 

O00–O07: Pregnancy with abortive outcomes 0.2 (0.0 – 0.5) 

O10–O16: Edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium 0.4 (0.0 – 0.7) 

O20–O29: Other maternal disorders predominantly related to pregnancy 3.5 (3.1 – 4.0) 

O26.6: Liver disorders in pregnancy, childbirth and the puerperium 0.5 (0.3 – 0.7) 

O26.8: Other specified pregnancy-related conditions 2.6 (2.2 – 2.9) 

O20–O29: Other maternal disorders predominantly related to pregnancy, excluding O26.8 1.0 (0.8 – 1.3) 

O30–O48: Maternal care related to the fetus and amniotic cavity and possible delivery problems 0.3 (0.0 – 0.5) 

O60–O75: Complications of labor and delivery 0.2 (– 0.1 – 0.5) 

O85–O92: Complications predominantly related to the puerperium 0.4 (0.0 – 0.8) 

Indirect causes 4.6 (4.1 – 5.1) 

Alternative grouping of indirect causes (O98–O99) 4.2 (3.7 – 4.7) 

O95–O99: Other obstetric conditions not elsewhere classified (including late maternal deaths) 8.3 (7.6 – 9.0) 

O95,O98–O99: Other obstetric conditions not elsewhere classified (excluding late maternal deaths) 5.1 (4.6 – 5.6) 

O99.3: Mental disorders and diseases of the nervous system complicating pregnancy, childbirth and the puerperium 0.2 (0.1 – 0.3) 

O99.4: Diseases of the circulatory system complicating pregnancy, childbirth and the puerperium 1.2 (0.9 – 1.4) 

O99.5: Diseases of the respiratory system complicating pregnancy, childbirth and the puerperium 0.4 (0.2 – 0.6) 

O99.8: Other specified diseases and conditions complicating pregnancy, childbirth and the puerperium 2.3 (1.9 – 2.6) 

O96–O97: Late maternal deaths 3.5 (3.1 – 3.9) 

Nonspecific causes (O26.8,O95,O99.8) 5.6 (5.1 – 6.1) 

NOTES: CI is confidence interval. Direct and indirect causes of maternal death from Say et al.; see reference 26 in this report. Alternative grouping of direct 

causes of maternal death (A34,O00–O92) and indirect causes (O98–O99) from MacDorman et al.; see reference 4 in this report. Alternative grouping of 

direct causes of maternal death (A34,O00–O95) from Hoyert et al.; see reference 15 in this report. 

SOURCE: NCHS, National Vital Statistics System, 1999–2017. 

NATIONAL CENTER FOR HEALTH STATISTICS 24 Series 3, Number 44 
Table 4. Estimated trends in predicted maternal mortality rates, by cause of death: United States, 1999–2017 

Average annual change in maternal mortality rate 

No checkbox All checkbox 

Cause of maternal death (95% CI) p (95% CI) p

Direct causes – 0.05 (–0.10 – 0.01) 0.083 – 0.08 (–0.17 – 0.01) 0.099 

Direct causes excluding O26.8 – 0.17 (–0.22 – –0.12) Less than 0.001 – 0.22 (–0.30 – – 0.15) Less than 0.001 

Alternative grouping of direct causes (A34,O00–O92) 0.00 (–0.05 – 0.06) 0.950 0.00 (–0.08 – 0.09) 0.953 

Alternative grouping of direct causes (A34,O00–O95) – 0.03 (–0.09 – 0.02) 0.228 – 0.05 (–0.15 – 0.04) 0.242 

O00–O07: Pregnancy with abortive outcomes – 0.03 (–0.05 – –0.02) Less than 0.001 – 0.05 (–0.07 – – 0.02) 0.001 

O10–O16: Edema, proteinuria and hypertensive disorders in 

pregnancy, childbirth and the puerperium – 0.03 (–0.05 – 0.00) 0.019 – 0.04 (–0.07 – 0.00) 0.045 

O20–O29: Other maternal disorders predominantly 

related to pregnancy 0.09 (0.06 – 0.12) Less than 0.001 0.26 (0.21 – 0.31) Less than 0.001 

O26.6: Liver disorders in pregnancy, childbirth and the 

puerperium 0.00 (0.00 – 0.01) 0.244 0.02 (–0.01 – 0.04) 0.145 

O26.8: Other specified pregnancy-related conditions 

(pregnancy-related exhaustion and fatigue, peripheral 

neuritis or renal disease) 0.08 (0.05 – 0.10) Less than 0.001 0.25 (0.21 – 0.29) Less than 0.001 

O20–O29: Other maternal disorders predominantly related to 

pregnancy, excluding O26.8 0.00 (–0.01 – 0.02) 0.575 0.01 (–0.02 – 0.04) 0.554 

O30–O48: Maternal care related to the fetus and amniotic cavity 

and possible delivery problems – 0.01 (–0.03 – 0.00) 0.039 – 0.02 (–0.05 – 0.00) 0.094 

O60–O75: Complications of labor and delivery – 0.06 (–0.08 – –0.04) Less than 0.001 – 0.08 (–0.11 – – 0.04) Less than 0.001 

O85–O92: Complications predominantly related to the 

puerperium – 0.03 (–0.06 – 0.00) 0.021 – 0.04 (–0.08 – 0.00) 0.045 

Indirect causes 0.03 (0.01 – 0.05) 0.008 0.10 (0.04 – 0.16) 0.002 

Alternative grouping of indirect causes (O98–O99) 0.02 (0.00 – 0.04) 0.037 0.07 (0.01 – 0.14) 0.019 

O95–O99: Other obstetric conditions not elsewhere classified 

(including late maternal deaths) 0.13 (0.09 – 0.16) Less than 0.001 0.39 (0.31 – 0.46) Less than 0.001 

O95,O98–O99: Other obstetric conditions not elsewhere 

classified (excluding late maternal deaths) 0.00 (–0.02 – 0.02) 0.895 0.00 (–0.07 – 0.08) 0.897 

O99.3: Mental disorders and diseases of the nervous system 

complicating pregnancy, childbirth and the puerperium 0.00 (0.00 – 0.01) 0.108 0.02 (0.01 – 0.03) 0.004 

O99.4: Diseases of the circulatory system complicating 

pregnancy, childbirth and the puerperium 0.00 (–0.01 – 0.02) 0.538 0.01 (–0.02 – 0.04) 0.514 

O99.5: Diseases of the respiratory system complicating 

pregnancy, childbirth and the puerperium 0.00 (–0.01 – 0.00) 0.089 – 0.02 (–0.04 – 0.01) 0.225 

O99.8: Other specified diseases and conditions complicating 

pregnancy, childbirth and the puerperium 0.01 (0.00 – 0.02) 0.141 0.04 (–0.01 – 0.08) 0.095 

O96–O97: Late maternal deaths 0.12 (0.09 – 0.15) Less than 0.001 0.34 (0.29 – 0.39) Less than 0.001 

Nonspecific causes (O26.8,O95,O99.8) 0.06 (0.04 – 0.09) Less than 0.001 0.23 (0.17 – 0.30) Less than 0.001 

NOTES: CI is confidence interval. Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between 

year and age and year and race and Hispanic origin. Models for O99.3 did not include state of occurrence. Direct and indirect causes of maternal death 

from Say et al.; see reference 26 in this report. Alternative grouping of direct causes of maternal death (A34,O00–O92) and indirect causes (O98–O99) from 

MacDorman et al.; see reference 4 in this report. Alternative grouping of direct causes of maternal death (A34,O00–O95) from Hoyert et al.; see reference 15 

in this report. 

SOURCE: NCHS, National Vital Statistics System, 1999–2017. 

Series 3, Number 44 25 NATIONAL CENTER FOR HEALTH STATISTICS 
Table 5. Estimated average change in the percentage of all deaths due to nonmaternal causes of death 

associated with the implementation of the revised standard death certificate, by age: United States, 2003–2017 

Change in percentage of all deaths 

15–44 years Under 10 years or 

Cause of death (95% CI) p 55–59 (95% CI) p

Unintentional injury (V01–X59,Y85–86) –0.14 (–0.43 – 0.15) 0.344 0.15 (0.00 – 0.29) 0.047 

Suicide (*U03,X60–X84,Y87.0) –0.04 (–0.22 – 0.13) 0.635 0.04 (–0.03 – 0.10) 0.304 

Drug overdose (X40–X44, X60–X64, X85, Y10–Y14) 0.86 (0.63 – 1.09) Less than 0.001 0.37 (0.28 – 0.46) Less than 0.001 

Homicide (*U01–*U02,X85–Y09,Y87.1) –0.10 (–0.24 – 0.04) 0.159 0.03 (–0.02 – 0.09) 0.253 

Unknown (R99) –0.40 (–0.50 – –0.31) Less than 0.001 –0.03 (–0.10 – 0.04) 0.445 

All –0.53 (–0.85 – –0.20) 0.001 0.21 (0.03 – 0.39) 0.020 

NOTES: CI is confidence interval. Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between 

year and age and year and race and Hispanic origin. 

SOURCE: CDC/NCHS, National Vital Statistics System, 1999–2017. 

NATIONAL CENTER FOR HEALTH STATISTICS 26 Series 3, Number 44 
Appendix I. Supplemental Tables 

and Details of Adjustments to 

Maternal Mortality Ratios for 

Misclassification 

Table I displays the percentage of records where one of to 1 year) among women of ages where pregnancy would 

the pregnancy checkboxes was selected (either currently be implausible (under age 10 or 55 and over) by state of 

pregnant, pregnant within 42 days, or pregnant 43 days occurrence. 

Table I. Percentage of deaths among female decedents under 10 years or 55 and over where one of the 

pregnancy checkboxes was selected, by state of occurrence: 2003–2013 

Under 10 55 and over 

State Percent N Percent N Row total percent 

Arizona 

Arkansas 

California 

Connecticut 

Delaware 

District of Columbia 

Florida 

Georgia 

Idaho 

Illinois 

Indiana 

Iowa 

Kansas 

Kentucky 

Louisiana 

Maine 

Michigan 

Minnesota 

Mississippi 

Missouri 

Montana 

Nebraska 

Nevada 

New Hampshire 

New Jersey 

New Mexico 

New York city 

New York state 

North Dakota 

Ohio 

0.00 

0.00 

0.19 

0.00 

0.00 

0.10 

0.00 

0.00 

0.00 

0.03 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.10 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.45 

0.00 

0.00 

0.05 

0.00 

0.00 

1,171 

985 

16,684 

1,026 

383 

963 

7,749 

3,184 

731 

3,420 

2,052 

278 

1,215 

751 

599 

195 

4,848 

624 

351 

1,308 

430 

793 

668 

331 

2,648 

695 

4,069 

4,173 

186 

4,275 

0.03 

0.01 

0.13 

0.02 

0.01 

0.05 

0.00 

0.02 

0.00 

0.02 

0.02 

0.01 

0.00 

0.08 

0.02 

0.00 

0.08 

0.01 

0.00 

0.02 

0.00 

0.00 

0.04 

0.06 

0.11 

0.02 

0.01 

0.08 

0.34 

0.02 

82,287 

75,536 

1,144,060 

127,400 

23,875 

20,136 

669,133 

186,774 

52,937 

274,518 

158,774 

40,410 

100,248 

74,324 

36,154 

23,942 

393,437 

56,209 

25,082 

103,928 

42,063 

65,048 

48,836 

48,203 

329,523 

50,912 

270,083 

502,104 

17,417 

354,857 

0.03 

0.01 

0.14 

0.02 

0.01 

0.06 

0.00 

0.02 

0.00 

0.02 

0.02 

0.01 

0.00 

0.07 

0.02 

0.00 

0.08 

0.01 

0.00 

0.02 

0.00 

0.00 

0.04 

0.06 

0.12 

0.02 

0.01 

0.08 

0.34 

0.02 

See footnotes at end of table. 

Series 3, Number 44 27 NATIONAL CENTER FOR HEALTH STATISTICS 
Table I. Percentage of deaths among female decedents under 10 years or 55 and over where one of the 

pregnancy checkboxes was selected, by state of occurrence: 2003–2013—Con. 

Under 10 55 and over 

State Percent N Percent N Row total percent 

Oklahoma 

Oregon 

Pennsylvania 

Rhode Island 

South Carolina 

South Dakota 

Tennessee 

Texas 

Utah 

Vermont 

Washington 

Wisconsin 

Wyoming 

0.04 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.06 

0.21 

0.00 

0.00 

0.00 

0.00 

2,299 

1,205 

1,125 

354 

2,163 

492 

763 

10,931 

1,424 

84 

2,335 

220 

165 

0.09 154,725 

0.01 116,620 

0.00 121,313 

0.06 38,025 

0.00 155,152 

0.00 32,372 

0.07 57,115 

0.05 571,070 

0.07 56,793 

0.02 14,747 

0.00 215,329 

0.01 22,968 

0.00 16,887 

0.09 

0.01 

0.00 

0.06 

0.00 

0.00 

0.07 

0.05 

0.07 

0.02 

0.00 

0.01 

0.00 

NOTES: Beginning in 2014, records indicating current or recent pregnancy among female decedents under 10 or 55 and over were recoded to “Not 

Applicable.” States that adopted the revised standard certificate in 2014 or later are therefore not shown. 

SOURCE: NCHS, National Vital Statistics System, 2003–2013. 

NATIONAL CENTER FOR HEALTH STATISTICS 28 Series 3, Number 44 
Table II displays differences in maternal mortality rates associated with the implementation of the checkbox by state of 

occurrence. 

Table II. Change in maternal mortality rates associated with the 

pregnancy checkbox implementation, by state of occurrence 

Change in maternal 

State mortality rate (95% CI) 

Alabama 29.0 (18.4 – 39.7) 

Alaska 4.0 (–8.7 – 16.7) 

Arizona 10.2 (2.2 – 18.1) 

Arkansas 15.7 (1.0 – 30.4) 

California 9.9 (5.2 – 14.7) 

Colorado 2.0 (–4.8 – 8.8) 

Connecticut 5.7 (–0.6 – 12.0) 

Delaware 19.0 (–15.5 – 53.5) 

District of Columbia 2.3 (–9.9 – 14.6) 

Florida 9.3 (4.8 – 13.7) 

Georgia 3.2 (–2.4 – 8.7) 

Hawaii –6.4 (–22.3 – 9.5) 

Idaho 23.9 (4.7 – 43.2) 

Illinois 17.9 (10.6 – 25.1) 

Indiana 20.4 (14.3 – 26.5) 

Iowa 9.5 (–1.7 – 20.7) 

Kansas 14.0 (4.3 – 23.8) 

Kentucky 11.6 (0.6 – 22.7) 

Louisiana 38.2 (28.4 – 48.0) 

Maine 6.9 (–13.5 – 27.3) 

Maryland –7.8 (–13.3 – –2.4) 

Massachusetts 2.4 (–1.6 – 6.5) 

Michigan 29.9 (20.4 – 39.3) 

Minnesota 1.5 (–6.2 – 9.2) 

Mississippi –10.0 (–21.4 – 1.5) 

Missouri 6.5 (–3.9 – 16.9) 

Montana 0.4 (–24.2 – 25.0) 

Nebraska –2.6 (–16.8 – 11.7) 

Nevada –1.3 (–12.7 – 10.0) 

New Hampshire 5.3 (–12.9 – 23.4) 

New Jersey 16.1 (11.0 – 21.1) 

New Mexico 15.7 (–5.9 – 37.2) 

New York City 

New York State1 

9.3 (2.7 – 15.9) 

6.6 (1.8 – 11.3) 

North Carolina 9.5 (5.0 – 14.1) 

North Dakota 25.3 (–14.3 – 64.9) 

Ohio 19.6 (12.7 – 26.4) 

Oklahoma 29.9 (16.0 – 43.8) 

Oregon 5.1 (–3.7 – 13.9) 

Pennsylvania – 2.4 (–8.4 – 3.6) 

Rhode Island –0.8 (–13.5 – 11.8) 

South Carolina 18.3 (9.8 – 26.7) 

South Dakota 14.8 (–7.1 – 36.7) 

Tennessee 18.8 (11.2 – 26.3) 

Texas 12.5 (8.8 – 16.1) 

Utah 10.9 (0.1 – 21.6) 

Vermont 4.4 (–16.6 – 25.4) 

Virginia 7.4 (2.5 – 12.3) 

Washington 3.7 (–2.3 – 9.6) 

West Virginia 4.6 (–17.4 – 26.6) 

Wisconsin –4.8 (–12.9 – 3.2) 

Wyoming 84.4 (–22.5 – 191.3) 

1

Excludes New York City.
 

NOTE: CI is confidence interval.
 

SOURCE: NCHS, National Vital Statistics System, 1999–2017.
 

Series 3, Number 44 29 NATIONAL CENTER FOR HEALTH STATISTICS 
Table III displays the observed maternal mortality rates MMRs assuming that all states had adopted the checkbox 

(MMRs), predicted MMRs assuming that no states had during the entire time period. 

adopted the checkbox during this time period, and predicted 

Table III. Observed and predicted maternal mortality rates: United States, 1999–2017 

Predicted maternal mortality rate, Predicted maternal mortality rate, 

Year Maternal mortality rate no checkbox all checkbox 

1999 9.9 (8.9 – 10.9) 10.3 (7.4 – 13.2) 21.2 (11.2 – 31.2) 

2000 9.8 (8.8 – 10.8) 10.1 (7.2 – 13.0) 20.8 (11.6 – 30.0) 

2001 9.9 (8.9 – 10.9) 10.0 (7.3 – 12.7) 20.3 (11.5 – 29.1) 

2002 8.9 (8.0 – 9.8) 9.8 (7.3 – 12.3) 19.8 (12.0 – 27.6) 

2003 12.1 (11.0 – 13.2) 9.7 (7.2 – 12.2) 19.5 (12.4 – 26.6) 

2004 13.1 (12.0 – 14.2) 9.7 (7.2 – 12.2) 19.2 (12.7 – 25.7) 

2005 15.1 (13.9 – 16.3) 9.6 (7.1 – 12.1) 19.0 (12.5 – 25.5) 

2006 13.3 (12.2 – 14.4) 9.7 (7.0 – 12.4) 18.7 (12.8 – 24.6) 

2007 12.7 (11.6 – 13.8) 9.7 (6.8 – 12.6) 18.6 (13.1 – 24.1) 

2008 15.5 (14.3 – 16.7) 9.8 (6.7 – 12.9) 18.7 (13.4 – 24.0) 

2009 16.6 (15.4 – 17.8) 9.9 (6.6 – 13.2) 18.9 (14.2 – 23.6) 

2010 16.9 (15.6 – 18.2) 10.1 (6.2 – 14.0) 19.2 (14.9 – 23.5) 

2011 19.3 (17.9 – 20.7) 10.4 (6.1 – 14.7) 19.6 (14.9 – 24.3) 

2012 19.9 (18.5 – 21.3) 10.6 (5.9 – 15.3) 19.9 (15.2 – 24.6) 

2013 22.0 (20.5 – 23.5) 10.9 (5.6 – 16.2) 20.5 (16.2 – 24.8) 

2014 21.5 (20.1 – 22.9) 11.3 (5.8 – 16.8) 20.9 (16.2 – 25.6) 

2015 20.9 (19.5 – 22.3) 11.7 (6.2 – 17.2) 21.7 (16.6 – 26.8) 

2016 21.8 (20.3 – 23.3) 12.2 (6.5 – 17.9) 22.4 (16.9 – 27.9) 

2017 21.6 (20.1 – 23.1) 12.8 (6.5 – 19.1) 23.5 (17.4 – 29.6) 

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as 

well as revision status. 

SOURCE: NCHS, National Vital Statistics System, 1999–2017. 

NATIONAL CENTER FOR HEALTH STATISTICS 30 Series 3, Number 44 
2017 

Table IV displays the predicted MMRs assuming that no the checkbox during the entire time period by varying 

states had adopted the checkbox during this time period, degrees of outcome misclassification. 

and predicted MMRs assuming that all states had adopted 

Table IV. Predicted maternal mortality rates, adjusted for outcome misclassification: United States, 1999 and 

Levels of outcome misclassification, by Predicted maternal mortality rate assuming Predicted maternal mortality rate assuming 

sensitivity and predictive value positive no states had adopted the checkbox all states had adopted the checkbox 

Sensitivity Predictive value positive 1999 2017 1999 2017 

0.3 0.5 17.1 21.4 35.3 39.2 

0.3 0.6 20.5 25.6 42.4 47.1 

0.3 0.7 24.0 29.9 49.5 54.9 

0.3 0.8 27.4 34.2 56.6 62.8 

0.3 0.9 30.8 38.5 63.6 70.6 

0.4 0.5 12.8 16.0 26.5 29.4 

0.4 0.6 15.4 19.2 31.8 35.3 

0.4 0.7 18.0 22.4 37.1 41.2 

0.4 0.8 20.5 25.6 42.4 47.1 

0.4 0.9 23.1 28.8 47.7 52.9 

0.5 0.5 10.3 12.8 21.2 23.5 

0.5 0.6 12.3 15.4 25.4 28.2 

0.5 0.7 14.4 17.9 29.7 32.9 

0.5 0.8 16.4 20.5 33.9 37.7 

0.5 0.9 18.5 23.1 38.2 42.4 

0.6 0.5 8.6 10.7 17.7 19.6 

0.6 0.6 10.3 12.8 21.2 23.5 

0.6 0.7 12.0 15.0 24.7 27.5 

0.6 0.8 13.7 17.1 28.3 31.4 

0.6 0.9 15.4 19.2 31.8 35.3 

0.7 0.5 7.3 9.2 15.1 16.8 

0.7 0.6 8.8 11.0 18.2 20.2 

0.7 0.7 10.3 12.8 21.2 23.5 

0.7 0.8 11.7 14.7 24.2 26.9 

0.7 0.9 13.2 16.5 27.3 30.3 

0.8 0.5 6.4 8.0 13.3 14.7 

0.8 0.6 7.7 9.6 15.9 17.6 

0.8 0.7 9.0 11.2 18.6 20.6 

0.8 0.8 10.3 12.8 21.2 23.5 

0.8 0.9 11.6 14.4 23.9 26.5 

0.9 0.5 5.7 7.1 11.8 13.1 

0.9 0.6 6.8 8.5 14.1 15.7 

0.9 0.7 8.0 10.0 16.5 18.3 

0.9 0.8 9.1 11.4 18.9 20.9 

0.9 0.9 10.3 12.8 21.2 23.5 

NOTE: Sensitivity refers to the proportion of true maternal deaths captured by death certificate data. Predictive value positive refers to the proportion of 

maternal deaths identified in death certificate data that are true maternal deaths. 

SOURCE: NCHS, National Vital Statistics System, 1999–2017. 

Series 3, Number 44 31 NATIONAL CENTER FOR HEALTH STATISTICS 
Table V displays how death certificate data compare with 

gold standard data, where Ty is the true number of maternal 

deaths, and Tn is the number of nonmaternal deaths, while 

Dy is the number of maternal deaths as indicated by death 

certificate data, and Dn is the number of nonmaternal deaths. 

Table V. Comparison of pregnancy status on death 

certificates with pregnancy status assessed by a gold 

standard measure 

Death certificate 

Gold standard Yes No Total 

Yes 

No 

a

c

b

d

Ty

Tn

Total Dy Dn Total number 

NOTE: The gold standard is based on prior analyses of the validity of death 

certificate data in ascertaining maternal deaths, which rely on linkages of 

death certificates with birth certificate, fetal death certificate, and electronic 

medical record data to determine whether a female decedent was currently 

or recently pregnant. 

Sensitivity (Se) is the proportion of true maternal deaths 

classified as maternal deaths on the death certificate. 

Predictive value positive (PVP) is the proportion of maternal 

deaths in mortality data that are truly maternal deaths. The 

proportion of maternal deaths from death certificate data 

that are false positives (FP) is 1 – PVP, corresponding to the 

proportion of maternal deaths with no evidence of current 

or recent pregnancy. Using these values, the true number of 

maternal deaths corrected for misclassification, Ty , can be 

calculated as follows: 

a Se = (1) Ty 

Therefore, 

a = Se • Ty (2)

Additionally, 

a PVP = (3) Dy 

c FP = (1 – PVP) = (4) Dy 

Therefore, 

c = (1 – PVP) • Dy (5)

Ty is unknown, while Dy is observed, and values for Se and 

PVP are estimated from prior studies. 

Dy = a + c = Se • Ty + (1 – PVP) • Dy (6)

The following formula can then be used to calculate Ty from 

Se, PVP, and Dy: 

Dy – (1 – PVP) • Dy Dy • PVP Ty = = (7) Se Se 

NATIONAL CENTER FOR HEALTH STATISTICS 32 Series 3, Number 44 
Technical Notes 

Cause-of-death classification 

Mortality statistics are compiled in accordance with World 

Health Organization (WHO) regulations specifying that 

WHO member nations classify and code causes of death in 

accordance with the current revision of the International 

Statistical Classification of Diseases and Related Health 

Problems (ICD). ICD provides the basic guidance used in 

virtually all countries to code and classify causes of death. It 

provides not only disease, injury, and poisoning categories, 

but also the rules used to select the single underlying cause 

of death for tabulation from the conditions reported on the 

death certificate, as well as definitions, tabulation lists, the 

format of the death certificate, and regulations on use of 

the classification. Causes of death for data presented in this 

report were coded according to ICD guidelines described 

in annual issues of the National Center for Health Statistics 

instruction manuals (39). 

Series 3, Number 44 33 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTES: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin. Direct causes of maternal death from Say et al.; see reference 26 in this report.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and 

Hispanic origin. Direct causes of matamal death from Say et al.; see reference 26 In this report. 

SOURCE: NCHS, National Vital Statistics System. 

Appendix II. Supplemental Figures 

Figure I. Observed and predicted maternal mortality rates for direct causes of maternal death: United States, 

1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 34 Series 3, Number 44 
NOTES: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and Hispanic

origin. Direct causes of maternal death from Say et al.; see reference 26 in this report.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and Hispanic

origin. Alternative grouping of direct causes of maternal death (A34,000-092) from MacDorman et al.; see reference 4 in this report.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Models were adjusted fer age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and Hispanic 

origin. Direct causes of maternal death from Say et al.; see reference 26 in this report. 

SOURCE: NCHS, National VHal Statistics System. 

NOTES: Models were adjustad for age group, race and Hispanic origin, and stats of occurrence, and includad interactions between year and age, and year and race and Hispanic 

origin. AHarnattva grouping of direct causes of maternal death (A34,000--092) from MacDorman et al.; see reference 4 In this report. 

SOURCE: NCHS, National Vrtal Statistics Systam. 

Figure II. Observed and predicted maternal mortality rates for direct causes of maternal death, excluding O26.8: 

United States, 1999–2017 

Figure III. Observed and predicted maternal mortality rates for direct causes of maternal death (A34, O00–O92): 

United States, 1999–2017 

Series 3, Number 44 35 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTES: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and Hispanic

origin. Alternative grouping of direct causes of maternal death (A34,000-095) from Hoyert etal.; see reference 15 in this report.

SOURCE: NCHS, National Vital Statistics System.

10bserved rates suppressed when the number of deaths is fewerthan 20 (2002,2015,2017).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Models were adjusted for age gmup, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and Hispanic 

origin. Alternative gmuping of direct causes of maternal death (A34,000-095) from Hoyart et al.; see reference 15 in this report 

SOURCE: NCHS, National Vital Statistics System. 

1 Observed rates suppressed when the number of deaths Is fewer than 20 (2002, 2015, 2017). 

NOTE: Models were adjusted for age gmup, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and 

Hispanic origin. 

SOURCE: NCHS, National Vita.I Statistics System. 

Figure IV. Observed and predicted maternal mortality rates for direct causes of maternal death (A34, O00–O95): 

United States, 1999–2017 

Figure V. Observed and predicted maternal mortality rates for pregnancy with abortive outcomes (O00–O07): 

United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 36 Series 3, Number 44 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjusted fur age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and 

Hispanic origin. 

SOURCE: NCHS, National Vital Statistics System. 

NOTE: Models were adjusted fur age group, race and Hispanic origin, and state of occurrence, and Included lnteracUons between year and age, and year and race and 

Hispanic origin. 

SOURCE: NCHS, National Vital statistics System. 

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and 

Hispanic origin. 

SOURCE: NCHS, National Vital Statistics System. 

Figure VI. Observed and predicted maternal mortality rates for edema, proteinuria, and hypertensive disorders in 

pregnancy, childbirth, and the puerperium (O10–O16): United States, 1999–2017 

Figure VII. Observed and predicted maternal mortality rates for other maternal disorders predominantly related to 

pregnancy (O20–O29): United States, 1999–2017 

Series 3, Number 44 37 NATIONAL CENTER FOR HEALTH STATISTICS 
1Observed rates suppressed when the number of deaths is fewerthan 20 (priorto 2008).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

'Observed rates suppressed when the number of deaths is fewerthan 20 (priorto 2002).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

38

Figure VIII. Observed and predicted maternal mortality rates for liver disorders in pregnancy, childbirth, and the 

puerperium (O26.6): United States, 1999–2017 

Figure IX. Observed and predicted maternal mortality rates for other specified pregnancy-related conditions (O26.8): 

United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 38 Series 3, Number 44 
1Observed rates suppressed when the number of deaths is fewerthan 20 (1999).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

'Observed rates suppressed when the number of deaths is fewerthan 20 (2002).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

39

Figure X. Observed and predicted maternal mortality rates for other maternal disorders predominantly related to 

pregnancy (O20–O29), excluding nonspecific O26.8: United States, 1999–2017 

Figure XI. Observed and predicted maternal mortality rates for maternal care related to the fetus and amniotic cavity 

and possible delivery problems (O30–O48): United States, 1999–2017 

Series 3, Number 44 39 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

Figure XII. Observed and predicted maternal mortality rates for complications of labor and delivery (O60–O75): 

United States, 1999–2017 

Figure XIII. Observed and predicted maternal mortality rates for complications predominantly related to the 

puerperium (O85–O92): United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 40 Series 3, Number 44 
NOTES: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and Hispanic

origin. Indirect causes of maternal death from Say et al.; see reference 26 in this report.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and Hispanic

origin. Alternative grouping of indirect causes of maternal death (098-099) from MacDorman et al.; see reference 4 in this report.

SOURCE: NCHS, National Vital Statistics System.

Figure XIV. Observed and predicted maternal mortality rates for indirect causes of maternal death: United States, 

1999–2017 

Figure XV. Observed and predicted maternal mortality rates for alternative grouping of indirect causes of maternal 

death (O98–O99): United States, 1999–2017 

Series 3, Number 44 41 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

Figure XVI. Observed and predicted maternal mortality rates for other obstetric conditions not elsewhere classified, 

including late maternal deaths (O95–O99): United States, 1999–2017 

Figure XVII. Observed and predicted maternal mortality rates for other obstetric conditions not elsewhere classified, 

excluding late maternal deaths (O95, O98–O99): United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 42 Series 3, Number 44 
1Observed rates suppressed when the number of deaths is fewerthan 20 (all years except 2009 and 2016).

NOTE: Models were adjusted for age group and race and Hispanic origin, and the interactions between year and these factors.

SOURCE: NCHS, National Vital Statistics System.

'Observed rates suppressed when the number of deaths is fewerthan 20 (priorto 2001).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

43

Figure XVIII. Observed and predicted maternal mortality rates for mental disorders and diseases of the nervous 

system complicating pregnancy, childbirth, and the puerperium (O99.3): United States, 1999–2017 

Figure XIX. Observed and predicted maternal mortality rates for diseases of the circulatory system complicating 

pregnancy, childbirth, and the puerperium (O99.4): United States, 1999–2017 

Series 3, Number 44 43 NATIONAL CENTER FOR HEALTH STATISTICS 
1Observed rates suppressed when the number of deaths is fewerthan 20 (all years).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

1Observed rates suppressed when the number of deaths is fewerthan 20 (2001-2002).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

44

Figure XX. Observed and predicted maternal mortality rates for diseases of the respiratory system complicating 

pregnancy, childbirth, and the puerperium (O99.5): United States, 1999–2017 

Figure XXI. Observed and predicted maternal mortality rates for other specified diseases and conditions complicating 

pregnancy, childbirth, and the puerperium (O99.8): United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 44 Series 3, Number 44 
1Observed rates suppressed when the number of deaths is fewerthan 20 (priorto 2002).

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between year and age, and year and race and

Hispanic origin.

SOURCE: NCHS, National Vital Statistics System.

Figure XXII. Observed and predicted maternal mortality rates for late maternal deaths (O96–O97): United States, 

1999–2017 

Figure XXIII. Observed and predicted maternal mortality rates for nonspecific causes of maternal death (O26.8, O95, 

O99.8): United States, 1999–2017 

Series 3, Number 44 45 NATIONAL CENTER FOR HEALTH STATISTICS 
1Observed rates suppressed when the number of deaths is fewerthan 20 (2000).

NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

Figure XXIV. Observed and predicted maternal mortality rates among females aged 15–19, adjusted for an error rate 

of 0.50% in the pregnancy checkbox: United States, 1999–2017 

Figure XXV. Observed and predicted maternal mortality rates among women aged 20–24, adjusted for an error rate of 

0.50% in the pregnancy checkbox: United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 46 Series 3, Number 44 
NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted forfixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted forfixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

Figure XXVI. Observed and predicted maternal mortality rates among women aged 25–29, adjusted for an error rate 

of 0.50% in the pregnancy checkbox: United States, 1999–2017 

Figure XXVII. Observed and predicted maternal mortality rates among women aged 30–34, adjusted for an error rate 

of 0.50% in the pregnancy checkbox: United States, 1999–2017 

Series 3, Number 44 47 NATIONAL CENTER FOR HEALTH STATISTICS 
NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted for fixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

NOTES: Dotted lines represent maternal mortality rates (MMRs) adjusted forfixed error rates, while solid lines depict the original predicted and observed MMRs. Models were

adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

Figure XXVIII. Observed and predicted maternal mortality rates among women aged 35–39, adjusted for an error rate 

of 0.50% in the pregnancy checkbox: United States, 1999–2017 

Figure XXIX. Observed and predicted maternal mortality rates among women aged 40 and over, adjusted for an error 

rate of 0.50% in the pregnancy checkbox: United States, 1999–2017 

NATIONAL CENTER FOR HEALTH STATISTICS 48 Series 3, Number 44 
NOTE: Models were adjusted for age group, race and Hispanic origin, and state of occurrence, and included interactions between these factors and year as well as revision status.

SOURCE: NCHS, National Vital Statistics System.

Figure XXX. Observed and predicted maternal mortality rates, by race and Hispanic origin, adjusted for an error rate of 0.50% in thUnited States, 1999–2017

Series 3, Number 44 49 NATIONAL CENTER FOR HEALTH STATISTICS 
 

AND HUMAN SERVICES

Centers f 

atistics System

NCHS reports can be downloaded from: 

Statistics System

Introduction

Maternal mortality has historically been used as a key 

 

 Classi 

Adoption of pregnancy status checkbox item

Research before 2003 (4–7) noted that NVSS underestimated 

 

Abstract

Objectives 

Maternal Mortality Statistics

NEW

To access other NCHS reports about maternal mortality, 

public-use data files, and resources, visit

https://www.cdc.gov/nchs/maternal-mortality/.

CS313496
Vital and Health Statistics 

Series Descriptions 

Active Series 

Series 1. Programs and Collection Procedures 

Reports describe the programs and data systems of the 

National Center for Health Statistics, and the data collection 

and survey methods used. Series 1 reports also include 

definitions, survey design, estimation, and other material 

necessary for understanding and analyzing the data. 

Series 2. Data Evaluation and Methods Research 

Reports present new statistical methodology including 

experimental tests of new survey methods, studies of vital and 

health statistics collection methods, new analytical techniques, 

objective evaluations of reliability of collected data, and 

contributions to statistical theory. Reports also include 

comparison of U.S. methodology with those of other countries. 

Series 3. Analytical and Epidemiological Studies 

Reports present data analyses, epidemiological studies, and 

descriptive statistics based on national surveys and data 

systems. As of 2015, Series 3 includes reports that would 

have previously been published in Series 5, 10–15, and 20–23. 

Discontinued Series 

Series 4. 	 Documents and Committee Reports 

Reports contain findings of major committees concerned with 

vital and health statistics and documents. The last Series 4 

report was published in 2002; these are now included in 

Series 2 or another appropriate series. 

Series 5. 	 International Vital and Health Statistics Reports 

Reports present analytical and descriptive comparisons of 

U.S. vital and health statistics with those of other countries. 

The last Series 5 report was published in 2003; these are now 

included in Series 3 or another appropriate series. 

Series 6. 	 Cognition and Survey Measurement 

Reports use methods of cognitive science to design, evaluate, 

and test survey instruments. The last Series 6 report was 

published in 1999; these are now included in Series 2. 

Series 10. 	 Data From the National Health Interview Survey 

Reports present statistics on illness; accidental injuries; 

disability; use of hospital, medical, dental, and other services; 

and other health-related topics. As of 2015, these are included 

in Series 3. 

Series 11.	 Data From the National Health Examination Survey, the 

National Health and Nutrition Examination Surveys, and 

the Hispanic Health and Nutrition Examination Survey 

Reports present 1) estimates of the medically defined 

prevalence of specific diseases in the United States and the 

distribution of the population with respect to physical, 

physiological, and psychological characteristics and 2) 

analysis of relationships among the various measurements. 

As of 2015, these are included in Series 3. 

Series 12. 	 Data From the Institutionalized Population Surveys 

The last Series 12 report was published in 1974; these reports 

were included in Series 13, and as of 2015 are in Series 3. 

Series 13. 	 Data From the National Health Care Survey 

Reports present statistics on health resources and use of 

health care resources based on data collected from health 

care providers and provider records. As of 2015, these reports 

are included in Series 3. 

Series 14.	 Data on Health Resources: Manpower and Facilities 

The last Series 14 report was published in 1989; these reports 

were included in Series 13, and are now included in Series 3. 

Series 15. 	 Data From Special Surveys 

Reports contain statistics on health and health-related topics 

from surveys that are not a part of the continuing data systems 

of the National Center for Health Statistics. The last Series 15 

report was published in 2002; these reports are now included 

in Series 3. 

Series 16. 	 Compilations of Advance Data From Vital and Health 

Statistics 

The last Series 16 report was published in 1996. All reports 

are available online; compilations are no longer needed. 

Series 20.	 Data on Mortality 

Reports include analyses by cause of death and demographic 

variables, and geographic and trend analyses. The last Series 

20 report was published in 2007; these reports are now 

included in Series 3. 

Series 21.	 Data on Natality, Marriage, and Divorce 

Reports include analyses by health and demographic 

variables, and geographic and trend analyses. The last Series 

21 report was published in 2006; these reports are now 

included in Series 3. 

Series 22. 	 Data From the National Mortality and Natality Surveys 

The last Series 22 report was published in 1973. Reports from 

sample surveys of vital records were included in Series 20 or 

21, and are now included in Series 3. 

Series 23.	 Data From the National Survey of Family Growth 

Reports contain statistics on factors that affect birth rates, 

factors affecting the formation and dissolution of families, and 

behavior related to the risk of HIV and other sexually 

transmitted diseases. The last Series 23 report was published 

in 2011; these reports are now included in Series 3. 

Series 24. 	 Compilations of Data on Natality, Mortality, Marriage, and 

Divorce 

The last Series 24 report was published in 1996. All reports 

are available online; compilations are no longer needed. 

For answers to questions about this report or for a list of reports published 

in these series, contact: 

Information Dissemination Staff 

National Center for Health Statistics 

Centers for Disease Control and Prevention 

3311 Toledo Road, Room 4551, MS P08 

Hyattsville, MD 20782 

Tel: 1–800–CDC–INFO (1–800–232–4636) 

TTY: 1–888–232–6348 

Internet: https://www.cdc.gov/nchs 

Online request form: https://www.cdc.gov/info 

For e-mail updates on NCHS publication releases, subscribe 

online at: https://www.cdc.gov/nchs/govdelivery.htm. 
U.S. DEPARTMENT OF

HEALTH & HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

3311 Toledo Road, Room 4551, MS P08

Hyattsville, MD 20782–2064

OFFICIAL BUSINESS 

PENALTY FOR PRIVATE USE, $300

FIRST CLASS MAIL

POSTAGE & FEES PAID

CDC/NCHS

PERMIT NO. G-284

U.S. DEPARTMENT OF

HEALTH & HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

3311 Toledo Road, Room 4551, MS P08

Hyattsville, MD 20782–2064

OFFICIAL BUSINESS 

PENALTY FOR PRIVATE USE, $300

FIRST CLASS MAIL

POSTAGE & FEES PAID

CDC/NCHS

PERMIT NO. G-284

For more NCHS Series Reports, visit: 

https://www.cdc.gov/nchs/products/series.htm 

DHHS Publication No. (PHS) 2020–1428, Series 3, No. 44
 

CS313703