NCHS Data Brief ■ No. 74 ■ September 2011

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Understanding Racial and Ethnic Disparities in

U.S. Infant Mortality Rates

Marian F. MacDorman, Ph.D., and T.J. Mathews, M.S.

Key findings

Data from the 2007 linked 

birth/infant death data set

•	 In	2007,	the	infant	mortality	

rate	for	non-Hispanic	black	

women	was	2.4	times	the	

rate	for	non-Hispanic	white	

women.	American	Indian	or	

Alaska	Native	(AIAN)	and	

Puerto	Rican	women	also	had	

relatively	high	infant	mortality	

rates.

•	 The	higher	infant	mortality	

rate	for	non-Hispanic	black	and	

Puerto	Rican	women,	compared	

with	non-Hispanic	white	

women,	was	primarily	due	to	

their	higher	levels	of	preterm	

births	and	preterm-related	

causes	of	death.

•	 In	contrast,	the	higher	infant	

mortality	rate	for	AIAN	

women	was	mostly	due	to	

higher	infant	mortality	rates	

for	term	and	near-term	infants,	

not	to	a	higher	percentage	of	

preterm	births.

•	 Higher	infant	mortality	

rates	from	sudden	infant	death	

syndrome	contributed	the	most	

to	the	infant	mortality	gap	

between	AIAN	and	

non-Hispanic	white	women.

Racial	and	ethnic	disparities	in	health	have	generated	increasing	attention	

and	concern	in	the	past	few	years	(1,2).	One	of	the	largest	disparities	found	

in	health	research	is	racial	and	ethnic	differences	in	infant	mortality	(1,2).	

Disparities	in	U.S.	infant	mortality	have	been	apparent	since	these	data	began	

to	be	collected	more	than	100	years	ago	(3).	These	disparities	have	persisted	

and	even	increased	over	time,	suggesting	that	not	all	racial	and	ethnic	groups	

have	benefited	equally	from	social	and	medical	advances	(1,4,5).	This	report	

examines	racial	and	ethnic	disparities	in	infant	mortality	rates	in	the	

United	States	with	a	particular	focus	on	explaining	the	high	infant	mortality	

rates	for	non-Hispanic	black,	American	Indian	or	Alaska	Native	(AIAN),	and	

Puerto	Rican	women.	Two	key	components	of	infant	mortality	are	analyzed:		

gestational	age-specific	infant	mortality	rates,	and	the	distribution	of	births	by	

gestational	age.	Differences	by	cause	of	death	are	also	examined.

Keywords: infant death • racial and ethnic differences • causes of infant death

U.S. infant mortality rates vary greatly by race and ethnicity.

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NCHS Data Brief ■ No. 74 ■ September 2011

■  2  ■

•	 In 2007, the infant mortality rate for non-Hispanic black women was 13.31 infant deaths per

1,000 live births, 2.4 times the rate for non-Hispanic white women (5.63) (Figure 1).

•	 The infant mortality rate for AIAN women (9.22) was 64 percent higher than the rate for

non-Hispanic white women.

•	 The infant mortality rate for Puerto Rican women (7.71) was 37 percent higher than the rate

for non-Hispanic white women.

•	 In contrast, infant mortality rates for Mexican, Cuban, Central and South American, and

Asian or Pacific Islander (API) women were 4–19 percent lower than for non-Hispanic

white women.

Gestational age-specific infant mortality rates vary widely among racial and 

ethnic groups.

•	 For very preterm infants (less than 32 weeks of gestation), infant mortality rates were 26

percent higher for non-Hispanic black and 14 percent lower for Central and South American

infants than for non-Hispanic white infants. Rates for the other racial and ethnic groups were

not significantly different from the non-Hispanic white rate. At 32–33 weeks of gestation,

differences among groups were not statistically significant (Table).

•	 Differences in gestational age-specific infant mortality were greater for infants at 34 weeks

of gestation or more than for shorter gestations. Infant mortality rates for AIAN women—

those with the highest mortality rates at this gestation—were twice those for non-Hispanic

white women. For non-Hispanic black women, infant mortality rates were 33–76 percent

higher for each gestational age grouping of 34 weeks or more than for non-Hispanic

white women.

•	 For Puerto Rican women, gestational age-specific infant mortality rates were generally not

significantly different compared with non-Hispanic white women.

Table. Gestational age-specific infant mortality rates, by race and Hispanic origin of mother: United States, 2007

Gestational age (weeks)

Total Less than 32 32–33 34–36 37–38 39–41 42 or more

Total 6.75 178.36 16.12 7.42 3.09 2.07 2.62

Non-Hispanic white 5.63 165.61 16.23 7.10 2.95 1.95 2.51

Non-Hispanic black 13.31 209.03 16.91 9.42 4.45 3.43 4.40

Hispanic 5.51 158.71 14.64 6.48 2.63 1.70 2.04

Mexican 5.42 161.31 15.11 6.67 2.69 1.66 2.10

Puerto Rican 7.71 172.18 * 8.15 3.11 2.32 *

Central and

 South American 4.57 142.09 13.52 5.24 2.02 1.41 *

American Indian or

 Alaska Native 9.22 156.99 28.51 14.27 6.14 3.79 *

Asian or Pacific

 Islander 4.78 173.30 14.84 5.59 2.12 1.43 1.69

* Figure does not meet standards of reliability or precision; based on fewer than 20 infant deaths in the numerator.

NOTE: Reliable rates cannot be computed for the Cuban population due to the small number of infant deaths (88).
NCHS Data Brief ■ No. 74 ■ September 2011

■  3  ■

•	 Infant	mortality	rates	were	lower	for	Central	and	South	American	and	API	women	at	34	

weeks	or	more,	and	for	Mexican	women	at	39–41	weeks,	compared	with	non-Hispanic	

white	women.

The percentage of infants born preterm varies widely by maternal race and 

ethnicity.

•	 Nearly	one	in	five	infants	of	non-Hispanic	black	women	(18.3	percent)	were	born	preterm.	

This	was	the	highest	level	among	the	racial	and	ethnic	groups—60	percent	higher	than	the	

percentage	for	non-Hispanic	white	women	(11.5	percent)	(Figure	2).

•	 For	non-Hispanic	black	women,	the	percentage	of	very	preterm	births	(less	than	32	weeks	of	

gestation)	was	4.1	percent,	more	than	twice	the	percentage	for	non-Hispanic	white	women	

(1.6	percent).	Very	preterm	infants	have	the	highest	infant	mortality	risk,	so	that	differences	

in	very	preterm	births	have	a	large	effect	on	the	overall	infant	mortality	rate.

•	 Compared	with	non-Hispanic	white	women,	the	percentage	of	preterm	births	was	3–26	

percent	higher	for	Mexican,	Central	and	South	American,	Cuban,	and	Puerto	Rican	women.

•	 API	women	had	the	lowest	percentage	of	preterm	births—5	percent	lower	than	for	

non-Hispanic	white	women.

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For non-Hispanic black women, preterm-related causes of death account 

for most of their higher infant mortality risk.

•	 Infant	mortality	rates	were	higher	for	non-Hispanic	black	than	for	non-Hispanic	white	

women	for	all	four	of	the	causes	of	death	shown	in	Figure	3.	The	largest	difference	was	for	

preterm-related	causes,	for	which	the	non-Hispanic	black	rate	was	more	than	three	times	the	

non-Hispanic	white	rate.
NCHS Data Brief ■ No. 74 ■ September 2011

■  4  ■

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•	 Infant	mortality	rates	for	sudden	infant	death	syndrome	(SIDS),	congenital	malformations,	

and	unintentional	injuries	were	also	substantially	higher	for	non-Hispanic	black	than	for	

non-Hispanic	white	women.

•	 Preterm-related	causes	accounted	for	more	than	one-half	of	the	difference	(55	percent)	

between	the	non-Hispanic	black	and	the	non-Hispanic	white	infant	mortality	rate.	SIDS	

accounted	for	6	percent,	congenital	malformations	5	percent,	and	unintentional	injuries	4	

percent	of	the	difference;	thus,	71	percent	of	the	difference	can	be	attributed	to	these	four	

causes	(calculation	not	shown—see	“Data	Source	and	Methods”).

For Puerto Rican women, preterm-related causes also explain most of their 

higher infant mortality risk.

•	 Infant	mortality	rates	for	preterm-related	causes	were	71	percent	higher,	and	rates	from	

congenital	malformations	were	10	percent	higher,	for	Puerto	Rican	women	than	for	nonHispanic	white	women	(Figure	4).

•	 SIDS	rates	were	the	same	for	Puerto	Rican	and	non-Hispanic	white	women,	while	a	reliable	

infant	mortality	rate	for	unintentional	injuries	could	not	be	computed	for	Puerto	Rican	

mothers	due	to	the	small	number	of	deaths	in	that	category.

•	 Preterm-related	causes	of	death	accounted	for	61	percent	of	the	difference	between	Puerto	

Rican	and	non-Hispanic	white	infant	mortality	rates,	and	congenital	malformations	

accounted	for	6	percent	of	the	difference;	thus,	these	two	causes	accounted	for	67	percent	of	

the	difference	(calculation	not	shown—see	“Data	Source	and	Methods”).
NCHS Data Brief ■ No. 74 ■ September 2011

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In contrast, higher SIDS rates contribute the most to the infant mortality 

gap between AIAN and non-Hispanic white women.

•	 The	AIAN	infant	mortality	rate	from	SIDS	was	2.4	times,	and	the	rate	from	unintentional	

injuries	was	2.3	times,	the	non-Hispanic	white	rate	(Figure	5).	The	AIAN	infant	mortality	

rates	for	these	two	causes	of	death	were	the	highest	among	the	racial	and	ethnic	

groups	studied.

•	 The	AIAN	infant	mortality	rate	from	congenital	malformations	was	48	percent	higher,	and	

the	rate	from	preterm-related	causes	was	26	percent	higher,	than	for	non-Hispanic	

white	women.

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NCHS Data Brief ■ No. 74 ■ September 2011

■  6  ■

•	 SIDS accounted for 23 percent of the difference between the AIAN and the non-Hispanic

white infant mortality rates. Congenital malformations accounted for 17 percent, pretermrelated causes accounted for 13 percent, and unintentional injuries accounted for 11 percent

of the difference; thus, the four causes combined accounted for 64 percent of the difference

(calculation not shown—see “Data Source and Methods”).

Summary

In the United States, different racial and ethnic groups have very different infant mortality

patterns. When assessing the relative contribution of the percentage of preterm births and

gestational age-specific infant mortality rates to racial and ethnic infant mortality differences,

we found that for non-Hispanic black women, 78 percent of their elevated infant mortality rate

compared with non-Hispanic white women was due to their higher percentage of preterm births,

while 22 percent was due to higher gestational age-specific infant mortality rates (primarily at

34 weeks of gestation or more). For Puerto Rican women, their elevated infant mortality rate

compared with non-Hispanic white women was entirely due to their higher percentage of preterm

births. However, AIAN women had a very different infant mortality pattern: 76 percent of their

higher infant mortality rate compared with non-Hispanic white women was due to their higher

gestational age-specific infant mortality rates (primarily at 34 weeks or more), and only 24

percent was due to their higher percentage of preterm births.

These findings are consistent with the cause-of-death analysis, which found that for both

non-Hispanic black and Puerto Rican women, most of their higher infant mortality rate compared

with non-Hispanic white women was due to preterm-related causes. In contrast, for AIAN

women, the infant mortality rate from SIDS was 2.4 times, and the rate from unintentional

injuries was 2.3 times, the non-Hispanic white rate. Infant mortality rates for non-Hispanic

black women would be reduced by 71 percent, those for AIAN women by 64 percent, and

those for Puerto Rican women by 67 percent if rates from preterm-related causes, congenital

malformations, SIDS, and unintentional injuries could be reduced to non-Hispanic white levels.

The different infant mortality patterns for non-Hispanic black, Puerto Rican, and AIAN women

suggest different prevention strategies (6,7). In addition, because the percentage of preterm births

for all U.S. racial and ethnic groups is higher than in other developed countries, all U.S. racial and

ethnic groups might benefit from prematurity prevention efforts (8,9).

Definitions

Infant death: Death of an infant before his or her first birthday.

Infant mortality rate: Number of infant deaths per 1,000 live births.

Gestational age-specific infant mortality rate: Number of infant deaths for a specific gestational

age group (for example, 32–33 weeks of gestation), divided by the number of live births for the

same gestational age group times 1,000.

Cause-specific infant mortality rate: Number of infant deaths from a particular cause of death

(e.g., SIDS) per 100,000 live births.

Preterm birth: Birth before 37 completed weeks of gestation.
NCHS Data Brief ■ No. 74 ■ September 2011

■  7  ■

Very preterm birth: Birth before 32 completed weeks of gestation.

Late preterm birth: Birth at 34–36 weeks of gestation.

Early term birth: Birth at 37–38 weeks of gestation.

Data source and methods

This report is based on data from the 2007 linked birth/infant death data set (5). In the linked data

set, information from the death certificate is linked to information from the birth certificate for

each infant under age 1 year who died in the 50 states, District of Columbia, and selected U.S.

territories. In the linked data set, the more reliable racial and ethnic data from the birth certificate

is used in both the numerator and denominator of infant mortality rate computations, thus

providing greater accuracy than other data sources.

The percent contribution of causes of death to the racial and ethnic infant mortality gap is

computed as the racial and ethnic difference in infant mortality rates for specific causes divided

by the racial and ethnic difference in the overall infant mortality rate times 100.

The percent contribution of the gestational age distribution and gestational age-specific infant

mortality rates to racial and ethnic differences in infant mortality rates is computed using the

Kitagawa method, which is described in detail elsewhere (10). Preterm-related causes of death are

those in which 75 percent or more of infants whose deaths were attributed to that cause were born

at less than 37 weeks of gestation, and the cause of death was a direct consequence of preterm

birth based on a clinical evaluation and review of the literature; this measure is described in

detail elsewhere (5,11,12).

About the authors

Marian F. MacDorman and T.J. Mathews are with the Centers for Disease Control and

Prevention’s National Center for Health Statistics, Division of Vital Statistics, Reproductive

Statistics Branch.

References

1.	 Centers for Disease Control and Prevention. CDC health disparities and inequalities report—

United States, 2011. MMWR 60(Suppl):1–116. 2011.

2.	 U.S. Department of Health and Human Services. Healthy people 2020 framework. 2010.

Available from: http://healthypeople.gov/2020/Consortium/HP2020Framework.pdf [Accessed

5/23/11].

3.	 Shapiro S, Schlesinger ER, Nesbitt REL Jr. Infant, perinatal, maternal and childhood mortality

in the United States. Cambridge, MA: Harvard University Press. 1968.

4.	 Krieger N, Rehkopf DH, Chen JT, Waterman PD, Marcelli E, Kennedy M. The fall and rise of

US inequities in premature mortality: 1960–2002. PLoS Med 5(2):e46. 2008.

5.	 Mathews TJ, MacDorman MF. Infant mortality statistics from the 2007 linked birth/infant

death data set. National vital statistics reports, vol 59 no 6. Hyattsville, MD: National Center for

Health Statistics. 2011.
NCHS Data Brief ■ No. 74 ■ September 2011

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6.	 Sappenfield WM, Peck MG, Gilbert CS, Haynatzka VR, Bryant T 3rd.

Perinatal periods of risk: Analytic preparation and phase 1 analytic methods

for investigating feto-infant mortality. Matern Child Health J 14(6):838–50.

2010.

7.	 Sappenfield WM, Peck MG, Gilbert CS, Haynatzka VR, Bryant T 3rd.

Perinatal periods of risk: Phase 2 analytic methods for further investigating

feto-infant mortality. Matern Child Health J 14(6):851–63. 2010.

8.	 MacDorman MF, Mathews TJ. Behind international rankings of infant

mortality: How the United States compares with Europe. NCHS data brief,

no 23. Hyattsville, MD: National Center for Health Statistics. 2009.

9.	 Ananth CV, Liu S, Joseph KS, Kramer MS. A comparison of foetal and

infant mortality in the United States and Canada. Int J Epidemiol 38:480–9.

2009.

10.	Kitagawa EM. Components of a difference between two rates. J Am Stat

Assoc 50(272):1168–94. 1955.

11.	Callaghan WM, MacDorman MF, Rasmussen SA, Qin C, Lackritz EM.

The contribution of preterm birth to infant mortality rates in the United

States. Pediatrics 118:1566–73. 2006.

12.	MacDorman MF, Callaghan WM, Mathews TJ, Hoyert DL, Kochanek

KD. Trends in preterm-related infant mortality by race and ethnicity, United

States, 1999–2004. Int J Health Serv 37(4):635–41. 2007.

Suggested citation

MacDorman MF, Mathews TJ.

Understanding racial and ethnic disparities

in U.S. infant mortality rates. NCHS data

brief, no 74. Hyattsville, MD: National

Center for Health Statistics. 2011.

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.

National Center for Health 

Statistics

Edward J. Sondik, Ph.D., Director

Jennifer H. Madans, Ph.D., Associate 

Director for Science

Division of Vital Statistics

Charles J. Rothwell, M.S., Director

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CS226189