TABLE 2

INFANT MORTALITY AMONG MEDICAID NEWBORNS BY

GESTATIONAL AGE AND BIRTHWEIGHT

North South
Florida Minnesota Carolina Carolina Texas?
Total
Number of Infant Deaths 374 156 336 196 252
Infant Deaths Per 1,000 Live Births 104 13.3 162 16.6 98
Gestational Age
< 28 Weeks
Number of Infants Deaths 92 37 98 53
Infant Deaths Per 1,000 Live Births 260.6 528.6 360.3 A173
28-30 Weeks
Number of Infants Deaths 31 9 21 14 18
Infant Deaths Per 1,000 Live Births 68.1 125.0 "7 TAS 59.6
31-32. Weeks
Number of Infants Deaths 25 10 u il 16
Infant Deaths Per 1,000 Live Births 427 131.6 313 46.4 40.3
> 32 Weeks
Number of Infants Deaths 195 91 206 118 138
Infant Deaths Per 1,000 Live Births 5.8 84 10.4 10.6 5.9
Unknown
Number of Infants Deaths 3 9 0 0 28
Infant Deaths Per 1,000 Live Births 30.9 14.2 0 0 18.7
Birthweight
< 1.500 Grams
Number of Infants Deaths 164 50 149 90 95
Infant Deaths Per 1.000 Live Births 210.8 294.1 282. 306.1 186.3
1.500-2,499 Grams
Number of infants Deaths ST 7 52 35 SI
Infant Deaths Per 1,000 Live Births 16.7 444 284 28.7 228
2,500 Grams and Over
Number of Infants Deaths 150 6S 1 103
Infant Deaths Per 1.000 Live Births 47 61 78 7.0 48
SOURCE: — WIC/Medicaid newborn database
NOTE: “The intant mortahty rate is the number of deaths 1 Medicaid antants less than one year of age per 1,000 live births, In Texas.

the rate relers 10 deaths of infants less than of equal to six months ot age

“Infants deaths refer to deaths of infants less tha or equal to six months of age



FINDINGS
FROM THE
LITERATURE

or more of the risk criteria for eligibility. If she is eligible, she receives a
nutrition education session and food instruments for the purchase of a
food package from a participating vendor. Usually (though not always),
application, eligibility determination, service receipt, and health care
referrals all occur in the initial visit. The frequency of food instrument
pick-up varies from once every month to once every three months (at
which time food instruments for three months are picked up). In
subsequent months, the participant will then return to the WIC office
periodically in order to pick up her WIC food instrument and receive
nutrition education services. Prenatal participants are eligible for WIC
benefits through the end of the pregnancy and up to six weeks
postpartum.

Authorized under Title XIX of the Social Security Act, Medicaid is a joint
federal and state program that reimburses the covered medical-care costs
of low-income persons. It is the nation’s largest program providing
reimbursement for health care services to the poor, but not all low-income
persons are eligible. Eligibility depends on categorical status in addition
to income, and states have considerable discretion in determining income
eligibility ceilings. In the five study states, the income-eligibility ceiling for
Medicaid during the study period was lower than the eligibility ceiling for
the WIC program, ranging from 33 percent of the poverty level in Texas
to 88 percent of the poverty level in Minnesota. Since 1987, Medicaid has
increased the income eligibility standards for pregnant women and
children. Currently, states are required to expand Medicaid coverage to
pregnant women and children whose incomes are below 133 percent of
the federal poverty level; in addition, states currently have the option to
provide coverage up to 185 percent of the poverty level.

As the WIC program has expanded over the last two decades.
numerous and varied evaluations of the WIC program have been
conducted. This section summarizes the findings of WIC impact studics
that have cxamined infant mortality, or the three outcomes that are
closely related to infant mortality: birthweight, fetal mortality, and
gestational age.

Seven major studies of the effects of the WIC program were conducted
after the program's inception in 1972 and examined at least one of the
variables of interest (infant mortality, birthweight, fetal mortality, and
gestational agc). The primary findings of these studies are discussed
below:



TABLE 3 (continued)

North South
Florida Minnesota Carolina Carolina Texas*
Plorality
Singleton
Number of Infant Deaths 341 145 306 178 222
Infant Deaths Per 1,000 Live Births 97 127 15.2 15.5 88
Multiple Birth
Number of Infant Deaths 33 1 30 18 30
Infant Deaths Per 1,000 Live Births 37.0 36.5 53.5 62.7 45.5
Kessner Index
Inadequate
Number of Infant Deaths 93 27 3 58 64
Infant Deaths Per 1,000 Live Births 175 233 33.7 28.2 125
Intermediate
Number of Infant Deaths 140 48 145 80 89
Infant Deaths Per 1,000 Live Births 87 118 173 138 83
Adequate
Number of Infant Deaths nz 49 115 54 65
Infant Deaths Per 1.000 Live Births 8s 10.2 11.5 14.6 8.2
Unknown
Number of Infant Deaths 2 2 13 4 34
Infant Deaths Per 1.000 Live Births 24,7 18.6 26.4 18.3 16.6
SOURCE: WIC-Medicaid newborn database.
NOT: The infant mortality rate is the number of deaths 10 Medicaid infants less than one year of age per 1.000 live hirths, In Texas.

the rate refers to deaths of infants less than or equal to six months of age.
“Intant deaths refer to deaths of infants less than or equal to six months of age.

“Racialiethnicity groups varied across states. In North Carolina and South Carolina, a small number of women classified neither as white
nor black are included with black women. In Texas, “black” means "black, nonspanish.”

16



TABLES

Table Page

1 INFANT MORTALITY RATES IN THE FIVE STUDY

STATES, 1987 2... 2.602 11
2 INFANT MORTALITY AMONG MEDICAID NEWBORNS

BY GESTATIONAL AGE AND BIRTHWEIGHT ...............-- 12
3 DESCRIPTIVE DATA ON INFANT MORTALITY AMONG

MEDICAID NEWBORNS ..........00 0000: e cence eee eens 15
4 INFANT NEONATAL, AND POSTNEONATAL MORTALITY

RATES AMONG MEDICAID NEWBORNS ............000000005 18
5 ESTIMATED EFFECTS OF PRENATAL WIC PARTICIPA-

TION ON DEATH RATES OF MEDICAID NEWBORNS .......... 21
6 ESTIMATED EFFECTS OF PRENATAL CARE ADEQUACY

ON DEATH RATES OF MEDICAID NEWBORNS ............--+ 25
7 ESTIMATED NUMBER OF INFANT DEATHS PREVENTED

BY PRENATAL WIC PARTICIPATION ...........0-.-.00-.20000- 26



(1,500-2,499 grams) were also considerably higher than average. In
contrast, the incidence of infant mortality for Medicaid newborns with
gestational age greater than 32 weeks was quite low, at roughly 5.6 infant
deaths per 1,000 live births.

This strong relationship among gestational age, birthweight, and infant
mortality has important implications for an analysis of the impacts of
prenatal WIC participation on infant mortality. The primary WIC
participation variable used in the WIC-Medicaid study is a simple binary
variable that equals one if the woman participated in the WIC program
any time during her pregnancy and equals zero otherwise. Thus, WIC
participants include some women who enrolled early in pregnancy and
some who enrolled late in pregnancy. The pregnancy outcomes are likely
to be more favorable for the group of later WIC enrollees relative to early
enrollees in the WIC program for reasons that are related mostly to
longer pregnancy durations rather than to prenatal WIC participation. In
addition, for the later enrollees, there is the potential for an
overstatement of the effects of prenatal WIC participation since birth
outcomes for late WIC enrollees with longer gestational ages are
compared with the birth outcomes for nonparticipants, some of whom had
low-gestational age births and did not have the opportunity to enroll later
as prenatal WIC participants.

This issue of the timing of prenatal WIC enrollment is particularly
important in the context of an analysis of infant mortality. If a woman
enrolls in the WIC program late during pregnancy (e.g., after 32 wecks
gestation), she is less likely to have an infant who dies for the simple
reason that the incidence of infant mortality drops sharply with gestational
age. That is, late WIC enrollees are likely to have higher birthweight
newborns and are less likely to have newborns who die, yet it would be
incorrect to attribute the effect of the duration of pregnancy on birth
outcomes to WIC participation.

To account for the relationship between gestational age and the incidence
of infant mortality. we define WIC participants as women who enrolled in
the WIC program betore 30 weeks gestation. Specifically, prenatal WIC
participation is defined such that if a woman enrolled in the WIC program
after 30 wecks gestation and the value of her redeemed food instruments
was less than $80 (lor the three states with food instrument redemption
data) then she was considered a nonparticipant. The threshold of $80 for
the value of the redeemed food instruments is used to redefine late WIC
enrollees with less than 3 months of food instruments as nonparticipants.

13



The model estimated for this analysis is a reduced-form model of infant
mortality in which the infant death rates are a function of a set of
exogenous variables.” In addition to prenatal WIC participation, the
following variables were included as predictors of the infant death rates
(if they were available in the state’s database): the sex of the newborn.
multiple birth, maternal age, mother’s race/ethnicity, marital status.
prenatal care adequacy, number of previous live births, number of
previous pregnancy terminations, mother’s education, urban residence, and
whether the mother received prenatal care from a public health clinic.

Probit, a maximum likelihood estimation procedure for dichotomous
dependent variables. was used to estimate the state-specific infant
mortality models. Estimated probit coefficients do not have simple.
intuitive interpretations except to show the directions of the effects of the
independent variables on the likelihood or probability of an infant death.
However, the estimated coefficients can be used to calculate the predicted
infant, neonatal. or postneonatal mortality rates with and without prenatal
WIC participation. These predicted rates are constructed by computing
for each observation the predicted probability that the newborn dies
within a specific time period after birth when the WIC participation
variable is set equal to 0 (nonparticipant) for all observations and when
it is set equal to 1 (participant) for all observations. These probabilities
are then averaged, and the resulting averages are multiplied by 1,000 to
obtain the predicted mortality rates with and without the WIC program.
Similarly, predicted infant death rates for differing levels of prenatal care
can be constructed from probit coefficients. Predicted infant, neonatal.
and postnconatal mortality rates. as well as the estimated probit

*We also estimated a structural model of newborn birthweight and infant
mortality in which birthweight depends on prenatal WIC participation
(and other factors) and infant mortality depends on both birthweight and
prenatal WIC participation (and other factors). The structural model
specifies two effects of WIC participation on infant mortality--a direct
effect. controlling for birthweight, and an indirect effect operating through
WIC’s effect on birthweight and birthweight’s effect on infant mortality.
Unfortunately. it is very difficult to separate the effects of the explanatory
variables (especially prenatal WIC participation) on birthweight from their
eflects on infant mortality, As a result, the parameter estimates had large
standard errors and the structural model was estimated very impreciscly.
Appendix B describes further the structural model of infant mortality and
birthweight and includes detailed analysis results.

19



TABLE 3

DESCRIPTIVE DATA ON INFANT MORTALITY AMONG MEDICAID NEWBORNS

North South
Florida Minnesota Carolina Carolina Texas*
Total
Number of Infant Deaths 374 156 336 196 252
Infant Deaths Per 1,000 Live Births 10.4 133 162 16.6 98
WIC Participation
Participants by 30 Weeks
Number of Infant Deaths 90 162 73 56
Infant Deaths Per 1.000 Live Births 121 121 87 68
Nonparticipants by 30 Weeks
Number of Infant Deaths 66 174 123 196
Infant Deaths Per 1.000 Live Births 15.3 23.7 36.9 4
Race/Ethnicity of Mother?
White
Number of Infant Deaths us 112 us 53 68
Infant Deaths Per 1,000 Live Births 73 12.6 154 175 us
Black
Number of Infant Deaths 227 25 221 143 58
Infant Deaths Per 1,000 Live Births 13.6 22.7 16.9 164 8.1
Hispanic
Number of Infant Deaths 31 - - - 93
Infant Deaths Per 1.000 Live Births 9S - - 88
Native American
Number of Infant Deaths 12 ~ -
Infant Deaths Per 1.000 Live Births 14.8 -
Marital Status
Married
Number of Infant Deaths ua 10: 99 50 134
Infant Deaths Per 1,000 Live Births 9.0 15.5 15.0 14.2 10.9
Not Married
Number of Infant Deaths 200 52 237 146 16
Infant Deaths Per 1,000 Live Births n2 10.3 16.8 177 86
Age of Mother
< 18 Years of Age
Number of Infant Deaths a3 19 54 31 3
Infant Deaths Per 1.000 Live Births 100 212 18.8 20.2 RI
18-19 Years of Age
Number of Infant Deaths 61 32 66 41 4
Infant Deaths Per 1,000 Live Births 10.2 16.1 168 17.6 84
20-34 Years of Age
Number of Infant Deaths 281 wo 19 10
Infant Deaths Per 1.000 Live Births 10.3 1s 15.6 10.3
38 Years and Older
Number of Infant Deaths 19 6 8 s
Infant Deaths Per 1,000 Live Births 163 12.3 16.5 18.1

on



DESCRIPTIVE
ANALYSIS OF
INFANT
MORTALITY

Ill. ANALYSIS OF INFANT MORTALITY

This chapter describes the results from descriptive and multivariate
analyses of infant mortality among Medicaid newborns. The descriptive
analysis examines the incidence of infant mortality by maternal and
newborn characteristics. The multivariate analysis examines the
relationship between infant mortality and prenatal WIC participation
when other factors are controlled for.

The incidence of infant mortality among Medicaid newborns varied
significantly across the five study states, as shown in Table 1. Infant
mortality rates of Medicaid newborns, defined as the number of deaths
to infants under one year of age per 1,000 live Medicaid births, ranged
from 10.4 in Florida to 13.3 in Minnesota to 16.2 and 16.6 in North
Carolina and South Carolina, respectively! At six months of age,
infant death rates were lowest for Florida and Texas at 9.4 and 9.8
deaths per 1,000 live births, respectively, and highest for South Carolina
and North Carolina with rates of 14.3 and 14.7, respectively. Infant
death rates during the first 28 days after birth were, on average.
between SO and 60 percent of the annual infant mortality rates and
ranged from 5.5 deaths per 1,000 live births in Texas to 9.2 in South
Carolina. With the exception of Florida, the infant mortality rate for
Medicaid newborns exceeded the infant mortality rate for all newborns
in cach state.

The infant mortality rate for Medicaid newborns is strongly related to
gestational age and birthweight, as shown in Table 2. Infant mortality
rates are very high for newborns born at less than 28 weeks gestation and
for those with very low birthweight (birthweight less than 1,500 grams).
Between one-quarter and one-half of newborns born at less than 28 wecks
gestation dicd within the first year of birth, and between 20 and 30,
percent of very low-birthweight newborns died within onc year of birth.
Although less extreme, infant mortality rates for newborns born at 28 to
32 weeks gestation or for newborns with moderately low birthweight

"Recall that the infant death data for Texas refer only to six months after
birth, rather than one year as in the other four states.

10



intermediate values of $347, $493, and $565 in Florida, Texas,
and South Carolina, respectively.

+ For newborns only, the estimated savings in Medicaid costs
from birth through 60 days were $744 in North Carolina and
$573 in Texas.

+ The estimated savings in Medicaid costs during the first 60
days after birth related to prenatal WIC participation exceeded
the costs of providing prenatal WIC benefits. For every dollar
spent on the prenatal WIC program, the associated savings in
Medicaid costs during the first 60 days after birth ranged from
$1.77 to $3.13 for newborns and mothers and from $2.84 to
$3.90 for newborns only.

. In all five study states, prenatal WIC participation by Medicaid
beneficiaries was associated with increased birthweight. The
average increase in birthweight related to prenatal WIC
participation by Medicaid beneficiaries ranged from 51 grams
in Minnesota to 73 and 77 grams in Florida and Texas,
respectively, to 113 and 117 grams in South Carolina and
North Carolina, respectively.

. Prenatal WIC participation by Medicaid beneficiaries was also
associated with a lower incidence of low birthweight newborns,
longer gestational age, and a lower incidence of preterm birth.

One important birth outcome not examined in the WIC-Medicaid study
is infant mortality. Infant mortality (deaths to infants up to one year of
age) in the United States remains a major public health policy concern.
In 1987, the United States ranked 24th in the world in infant mortality,
behind most developed and some developing countries. While U.S. infant
mortality rates declined dramatically from the mid 1960's to the early
1980's, the rate of decline slowed during the 1980's, and the infant
mortality rate for black infants remains approximately twice the rate for
white infants (National Center for Health Statistics, 1990). The WIC-
Medicaid database provides an opportunity to examine the incidence of
infant mortality among Medicaid newborns and to assess the relationship
between infant mortality and prenatal WIC participation. As described
below, the number of Medicaid newborn observations is very large (nearly
105,000), data are available on whether and when the newborn died, and

we



TABLE 6

ESTIMATED EFFECTS OF PRENATAL CARE ADEQUACY ON DEATH RATES OF MEDICAID NEWBORNS

Probit Coefficient Mortality Rate for Medicaid Newborns
Prenatal Care Prenatal Care Prenatal Care Prenatal Care Prenatal Care
Inadequate Intermediate Inadequate Intermediate Adequate

Florida

Infant Mortality Rate 244 ** 034 15.2 89 82

Neonatal Mortality Rate 170 * 005 8.0 SA 50

Postneonatal Mortality Rate 292 ** 069 12 3.9 32
Minnesota

Infant Mortality Rate 279 ++ 026 215 11.6 10.8

Neonatal Mortality Rate 242 -155 10.5 3.6 55

Postneonatal Mortality Rate 22" 140 11.2 78 $3
North Carolina

Infant Mortality Rate 344+ a7 +t 27.0 17.0 1s

Neonatal Mortality Rate 221* 08 116 81 65

Postneonatal Mortality Rate 409 ** 190 ** 15.7 89 53
South Carolina

Infant Mortality Rate 130 -.036 211 143 15.6

Neonatal Mortality Rate “078 -.109 87 8.0 10.8

Postneonatal Mortality Rate 3201" as 13.1 63 55
Texas

Infant Mortality Rate* 158 * O17 121 84 8.0

Neonatal Morality Rate 6} =085 0S 45 55

Postneonatal Mortality Rate 240 lob So 4.0 25

Source: WIC-Mediciud newborn database
Notr: Mortality rates are the number of deaths to Medicaid infants per 1.000 hye births
*Relers to deaths to Medicaid infants less than oF equal to 6 months of age

*(**): Significant at 0S(.01) level.

is)
nr



While these results suggest that prenatal WIC participation is associated
with reductions in infant death rates of Medicaid newborns, significant
differences are found in the magnitude of the WIC effects across the
study states. The estimated effect of prenatal WIC participation by
Medicaid beneficiaries on the incidence of infant mortality was greatest
for South Carolina, while no statistically significant effect was found for
Minnesota. Interstate comparisons of study findings must be made
cautiously, however, since the characteristics of the WIC and Medicaid
populations differed considerably across the study states, and such
differences are important factors in the assessment of the effects of WIC
participation.

Specifically, in 1987, the characteristics of the Medicaid-eligible
populations differed considerably across the five study states. Medicaid
beneficiaries in Minnesota were predominantly white and married, were
somewhat older. and had more years of education than those in the other
four states (Devaney, Bilheimer, and Schore 1990). In addition, because
of differences in the income-eligibility standards across the states, the
Medicaid populations in the study states were not comparable
socioeconomically. In 1987, the poverty income threshold for a family of
three was $9,056; across the five study states, the Medicaid income
eligibility thresholds ranged from 33 percent of the poverty level in Texas
($2,988 for a family of three) to 88 percent in Minnesot ($7,969 for a
family of three). The other three states had income eligibility thresholds
between 40 and 50 percent of the poverty level. The differences in
Medicaid income eligibility across the states during the study period are
likely to have a significant effect on the study findings and must be
considered when the implications of the analysis findings are assessed. A
priori, one would expect that the benefits of WIC program participation
would be greatest among the most severely disadvantaged women. This
expectation is consistent with the apparently smaller program impact in
Minnesota.

An important caveat to these findings is that the estimated effects of
prenatal WIC participation are not independent of any unmeasured
differences between WIC participants and nonparticipants that may also
influence infant death rates. WIC participants are a self-selected group
of women who may choose to participate in the WIC program for
underlying reasons that may independently lead to lower infant death
rates. For example. some pregnant women may not participate in the
WIC program because they lack access to or knowledge of publicly funded
programs that provide health care or other services, which also may affect

22



in infant mortality rates of Medicaid newborns resulting from
prenatal WIC participation are 3.6 infant deaths per 1,000 live
births in Florida, 4.0 in Texas (six-month mortality), 8.4 in
North Carolina, and 27.2 in South Carolina.

* Neonatal Mortality. The proportionate reductions in neonatal
mortality rates attributable to WIC are larger than the
proportionate reductions in infant mortality. The predicted
neonatal mortality rates for prenatal WIC participants are
roughly one-sixth to two-thirds the predicted neonatal
mortality rates for nonparticipants. The estimated reductions
in neonatal mortality rates of Medicaid newborns resulting
from prenatal WIC participation are 2.3 neonatal deaths per
1,000 live births in Florida, 3.0 in Texas, 7.3 in North Carolina,
and 19.9 in South Carolina.

*  Postneonatal Mortality. With the exception of South Carolina,
prenatal WIC participation is generally not associated with
postneonatal mortality of Medicaid newborns.

Two parts must be considered when these findings are interpreted. First,
the estimated effects of prenatal WIC participation on infant mortality are
independent of the effects of prenatal care on infant mortality. Infant
mortality of Medicaid newborns is also significantly related to the
adequacy of prenatal care. In all five states, receiving inadequate versus
either adequate or intermediate levels of prenatal care is associated with
a higher likelihood of an infant death. In addition, receiving inadequate
prenatal care has a stronger effect on postneonatal mortality than on
neonatal mortality.

The second point is that the estimated effects of prenatal WIC
Participation on infant mortality are not independent of unobserved
characteristics that might also influence infant mortality. WIC participants
arc a self-selected group of women who may choose to participate in the
WIC program for underlying reasons that may independently lead to lower
infant death ratcs. For example. some pregnant women may not
Participate in the WIC program because they lack access to or knowledge
of publicly funded programs that provide health care and other services.
which may independently affect birth outcomes. Thus, the estimated
effects of prenatal WIC participation on infant death rates may overstate
the truc effects since, relative to nonparticipants, WIC participants would

vi



EXECUTIVE SUMMARY

This study is an analysis of the relationship between prenatal participation
in the Special Supplemental Food Program for Women, Infants, and
Children (WIC) and infant mortality among Medicaid newborns. It is the
third report based on analysis conducted for The Savings in Medicaid Costs
for Newborns and Their Mothers From Prenatal Participation in the WIC
Program (the WIC-Medicaid study). Based on newborn analysis files, the
study includes all Medicaid births in 1987 for Florida, Minnesota, North
Carolina, and South Carolina, and all Medicaid births from January
through June 1988 in Texas.

Infant mortality is defined as the number of deaths to Medicaid infants
under one year of age per 1,000 live Medicaid births. Infant mortality has
two components--neonatal mortality and postneonatal mortality. Neonatal
mortality refers to death rates of Medicaid infants during the first 28 days
after birth, while postneonatal mortality refers to death rates of Medicaid
infants between 28 days and one year after birth.

Infant mortality rates of Medicaid newborns varied significantly across the
five study states, ranging from 10.4 deaths per 1,000 live births in Florida
to 13.3 in Minnesota to 16.2 and 16.6 in North Carolina and South
Carolina, respectively. (In Texas, the infant mortality rate for Medicaid
newborns was not available. since the infant death data refer only to six
months after birth.) Neonatal mortality rates of Medicaid newborns were,
on average, between 50 and 60 percent of the annual infant mortality
rates and ranged from 5.5 deaths per 1,000 live births in Texas to 9.2 in
South Carolina.

In Florida, North Carolina. South Carolina, and Texas, WIC participation
by 30 weeks gestation is associated with a significant reduction in infant
mortality, with most of the decline attributable to reductions in neonatal
mortality.

. Infant Mortality. With the exception of Minnesota, the
predicted infant mortality rates for prenatal WIC participants
are roughly one-quarter to two-thirds the predicted infant
mortality rates for nonparticipants. The estimated reductions



TABLE 1

INFANT MORTALITY RATES IN THE FIVE STUDY STATES, 1987

Medicaid Newborns

All Newborns

Died Within 28 Died Within6 Died Within 1
Days of Birth Months of Birth Year of Birth

Died Within 1
Year of Birth

Florida 6.1 9.4 10.4
Minnesota 6.2 11.7 13.3
North Carolina 8.4 14.7 16.2
South Carolina 9.2 14.3 16.6
Texas 5.5 9.8 na.

10.6

8.7

11.9

12.7

9.1

Source: WIC-Medicaid newborn database and National Center for Health Statistics 1989.

Note: The infant mortality rates are the number of infant deaths per 1,000 live births.

n.a.: not available.



WIC/MEDICAID
STUDY
FINDINGS

I. INTRODUCTION

This is the third report based on analyses conducted for The Savings in
Medicaid Costs for Newborns and Their Mothers From Prenatal
Participation in the WIC Program (the WIC-Medicaid study). The first
report examined the relationship between prenatal WIC participation.
Medicaid costs, and a variety of birth outcomes (Devaney, Bilheimer, and
Schore 1991, 1992), and the second examined very low birthweight among
Medicaid newborns (Devaney 1992). This third report presents the results
of an analysis of the relationship between prenatal WIC participation and
infant mortality among Medicaid newborns.

The report is organized in three chapters. The remainder of this chapter
provides a brief overview of the WIC-Medicaid study findings and the
database used in the study. Chapter II presents some background
material on the WIC and Medicaid programs and highlights findings from
previous research on infant mortality and its relationship to prenatal WIC
participation. Chapter III presents the findings from a descriptive and
multivariate analysis of infant mortality among Medicaid beneficiaries.

The WIC-Medicaid study examined the relationship between prenatal
WIC participation. Medicaid costs from birth to 60 days after birth, and
a varicty of birth outcomes. These outcomes included birthweight,
gestational age, the incidence of low birthweight, and the incidence of a
preterm birth for Medicaid beneficiaries. The study period included all
Medicaid births in 1987 for Florida, Minnesota, North Carolina, and
South Carolina and all Medicaid births from January through June 1988
in Texas.

The principal findings from the WIC-Medicaid study are the following
(Devaney ct al. 1990 and 1991):

. Prenatal WIC participation was associated with substantial
savings in Medicaid costs during the first 60 days after birth.
For newborns and their mothers, the estimated savings in
Medicaid costs during the first 60 days after birth associated
with prenatal participation in the WIC program ranged from
$277 in Minnesota to $598 in North Carolina, with



MULTIVARIATE
ANALYSIS OF
INFANT
MORTALITY

Index of prenatal care adequacy. In particular, women who received
inadequate levels of prenatal care had substantially higher infant mortality
rates than women who received either intermediate or adequate levels of
prenatal care. Interestingly, women with missing data on the adequacy of
prenatal care (because of missing data on either gestational age, number
of prenatal care visits, or the timing of the first prenatal care visit) also
had higher than average rates of infant mortality.

With the exception of Minnesota, more than half of the deaths to
Medicaid infants within the first year of life (six months in Texas)
occurred within the first 28 days after birth, as shown by the neonatal
mortality rates in Table 4. In Minnesota, about 46 percent of the
Medicaid infant deaths during the first year of life occurred in the
neonatal period. Differences in the infant death rates between prenatal
WIC participants and nonparticipants are proportionately greater for the
neonatal period than for the postneonatal period. The difference
between nonparticipants and prenatal WIC participants in the number of
neonatal infant deaths ranges from 1.5 deaths per 1,000 live births in
Minnesota to 19.4 in South Carolina. The difference in the postneonatal
mortality rates is somewhat smaller, ranging from 1.7 deaths per 1,000 live
births in Minnesota to 8.8 in South Carolina.

The multivariate analysis of infant mortality examines the relationship
between the likelihood of an infant death and prenatal WIC
participation. As suggested by the descriptive analysis, prenatal WIC
participation may have a greater effect on the likelihood of an infant
death shortly after birth than later during infancy. Therefore, three
dichotomous dependent variables were used in separate multivariate
specifications:

. Infant Mortality. a variable cqual to one if the newborn died
within one year of birth and cqual to zero otherwise

* Neonatal Mortality. a variable equal to one if the newborn died
within 28 days of birth and equal to zero otherwise

*  Postneonatal Mortality, a variable equal to one if the newborn
died between 28 days and one year after birth and equal to
zero otherwise



Infant Mortality
Among Medicaid
Newborns in Five
States: The Effects
of Prenatal WIC
Participation



preterm births (births of less than 37 weeks gestation) requires a
decreasing number of visits as the length of gestation decreases.

To conduct the analysis of the effects of prenatal WIC participation on
Medicaid costs and birth outcomes, the data on Medicaid costs, WIC
participation, and birth outcomes were combined for each Medicaid-
covered birth. Overall, the WIC/Medicaid analysis database includes
nearly 105,000 Medicaid births. The proportion of these births occurring
to WIC participants varied across the study states, ranging from nearly
one-half of the Medicaid births in Texas to almost three-quarters of the
Medicaid births in South Carolina.



WIC/MEDICAID
DATABASE

for each newborn, whether the mother participated in the WIC program
during pregnancy.

The database constructed for the WIC-Medicaid study served four
major purposes: (1) to identify Medicaid mothers and newborns, (2) to
provide information on Medicaid costs from birth to 60 days after birth,
(3) to determine whether the mother participated in the WIC program
while she was pregnant, and (4) to provide information on birth
outcomes and on the use of prenatal care. In each state, the analysis
database was constructed from the linkage of three main state data
files--the Medicaid paid claims and eligibility files, the WIC program
files, and the Vital Records birth and infant death files.

Medicaid eligibility and paid claims files were used to identify Medicaid-
covered births and to provide data on Medicaid costs for the analysis.
The analysis sample includes all Medicaid-covered births that occurred in
1987 in Florida, Minnesota, North Carolina and South Carolina, and those
in the first six months of 1988 in Texas. In Texas, the study is based on
all Medicaid births that occurred during the period from January through
June 1988, since the data necessary to identify WIC prenatal participants
were not available for births in an earlier period.

Data from the states’ WIC data systems were used to determine whether
a Medicaid-covered mother was receiving WIC benefits while she was
pregnant and. if so, the costs of providing the WIC food packages.

Data from the Vital Records birth and infant death files retained for the
study include: sex. number, duration of gestation, and birthweight of
newborns; whether the newborn died within one year of birth (six months
in Texas) and, if so, when; age, race, ethnicity, education, and marital
status of mothers; prenatal care adequacy; and number of previous live
births and previous pregnancy terminations. The adequacy of prenatal
care was measured with a modified Kessner Index (Kessner et al. 1973).
The Kessner Index combines information on the timing of entry into
prenatal carc with the number of visits recorded and the length of
pregnancy. For a full-term pregnancy. adequate prenatal care is defined
as nine or more visits, with the first visit occurring during the first
trimester of pregnancy: inadequate care is defined as four or fewer visits.
Intermediate care for a full-term pregnancy encompasses all levels of
prenatal care in between the two extremes. Adequate prenatal care for



Adequacy of
Prenatal Care

SUMMARY

The incidence of infant mortality is also significantly related to the
adequacy of prenatal care, as shown in Table 6 and in the detailed
tables contained in Appendix A. In all five states, receiving inadequate
versus either adequate or intermediate levels of prenatal care is
associated with a higher likelihood of an infant death. These findings
are consistent with the earlier WIC-Medicaid study findings that the
adequacy of prenatal care is significantly related to birth outcomes,
above and beyond the effects of prenatal WIC participation (Devaney.
Bilheimer, and Schore 1990).

An interesting result shown in Table 6 is that receiving inadequate levels
of prenatal care has a stronger effect on the likelihood of a postneonatal
death than on the likelihood of a neonatal death. The estimated
coefficients of inadequate prenatal care in the neonatal probits are
statistically significant only for Florida and North Carolina. In contrast,
for all five states, receiving inadequate levels of prenatal care is
consistently associated with a higher likelihood of a postneonatal infant
death.

In summary, prenatal WIC participation in Florida, North Carolina,
South Carolina, and Texas is associated with a reduction in the
likelihood of an infant death. In Minnesota, prenatal WIC
participation is not significantly related to the incidence of infant
mortality.

For women enrolling in the WIC program by 30 weeks gestation, the
estimated reduction in the infant mortality rate is 3.6 deaths per 1,000 live
births in Florida, 8.4 in North Carolina, 27.2 in South Carolina, and 4.0 in
Texas. Although these effects may seem small, it is important to
remember that infant deaths occur rarely compared to the number of
births, and, consequently, these participant-nonparticipant differences
represent large differences in the numbers of infants that die. As shown
in Table 7, with the exception of Minnesota, the estimated number of
infant deaths prevented by prenatal WIC participation by 30 wecks
gestation ranges from 114 deaths in Florida to 320 deaths in South
Carolina, with intermediate values of 103 deaths in Texas and 174 deaths
in North Carolina.



pregnancy outcomes. Thus, the estimated effects of prenatal WIC
participation on infant death rates may overstate the true effects since,
relative to nonparticipants, WIC participants would have lower infant
death rates even in the absence of the WIC program. Conversely, if the
WIC program is successful at reaching high-risk, low-income pregnant
women, infant death rates of WIC participants may be higher than for
nonparticipants, and the estimated effects of prenatal WIC participation
would understate the true effects.

In the absence of a true experimental design in which WIC-eligible
pregnant women would be randomly assigned to treatment and control
groups, it is extremely difficult to control for the effects of self-selection
when estimating the effects of prenatal WIC participation on infant
mortality. However, the problem introduced by self-selection may be
offset to some extent by the facts that: (1) the adequacy of prenatal care
is also likely to be related to any such underlying differences between
WIC participants and nonparticipants, and (2) the model controls for the
adequacy of prenatal care in estimating the effects of prenatal WIC
participation. However, the potential implications of the self-selection
issue should be kept in mind when interpreting the study findings.*

The analytic issues raised by the self-selection of WIC participants may be
particularly important for South Carolina, where the results indicate a very
large and statistically significant difference of 27.2 infant deaths per 1,000
live Medicaid births between WIC participants and nonparticipants. Of
the five study states, South Carolina had the highest infant mortal
among Medicaid newborns at 16.6 infant deaths per 1,000 live Medi
births and the highest prenatal WIC participation rate among Medicaid
beneficiaries at 75 percent. Infant mortality rates among the relatively
small percentage of Medicaid newborns whose mothers did not participate
in WIC during pregnancy were very high, as shown by both the descriptive
results presented in Table 3 and the multivariate results summarized in
Table 5. It is likely that these nonparticipants differed in important and
unobserved ways from WIC participants, and that these differences at
ieast partially explain the very large differences in infant mortality between
WIC participants and nonparticipants.

We estimated several selection bias models for the WIC-Medicaid study.
Unfortunately, because of the very limited set of independent variables
from the birth files. the selection bias models estimated for this study
yielded very unrealistic results that were extremely sensitive to both minor
changes in modcl specification and the estimation procedure employed.



have enhanced access to prenatal care and lower infant death rates even
in the absence of the WIC program. Conversely, if the WIC program is
successful at reaching high-risk, low-income pregnant women, infant death
rates of WIC participants may be higher than nonparticipants, and the
estimated effects of prenatal WIC participation would understate the true
effects. The problem introduced by self-selection may be offset to some
extent by the facts that (1) the adequacy of prenatal care is also likely to
be related to any such underlying differences between WIC participants
and nonparticipants, and (2) the analysis controls for the adequacy of
prenatal care in estimating the effects of prenatal WIC participation.
However, the potential implications of the self-selection issue should be
kept in mind when interpreting the study findings, particularly for South
Carolina, where the differences in infant mortality between WIC
participants and nonparticipants are very large.

vii



In South Carolina. a WIC enrollee is considered a nonparticipant if she
enrolled after 30 weeks gestation and if the number of food instruments
was less than 3. In Texas, a WIC enrollee is considered a nonparticipant
if she enrolled after 30 weeks gestation. (Texas was not able to provide
data on the number of food instrument issued or redeemed.)

Additional descriptive data on the incidence of infant mortality among
Medicaid newborns are presented in Table 3. In all five states, the infant
mortality rate of Medicaid newborns was lower for prenatal WIC
participants than for nonparticipants. The largest difference in the infant
mortality rates between WIC participants and nonparticipants was
observed in South Carolina, where nonparticipants had an infant mortality
rate that was approximately four times larger than the infant mortality rate
for WIC participants. In North Carolina, the infant mortality rate for
nonparticipants was nearly twice the infant mortality rate for prenatal
WIC participants. In Florida, Minnesota, and Texas, the differences
between WIC participants and nonparticipants were smaller, with the
infant mortality rates for nonparticipants between 25 and 80 percent
larger than the infant mortality rates for WIC participants.

Racial differences in infant mortality rates varied across the study states;
in Florida and Minnesota, infant mortality rates for black Medicaid
mothers were higher than the infant mortality rates for white Medicaid
mothers; in North Carolina and South Carolina, the infant mortality rates
of white and black Medicaid mothers were roughly equal; and in Texas.
the infant mortality rate for black Medicaid mothers was less than the
infant mortality rate for white Medicaid mothers.

Differences in infant mortality rates by marital status and age were
generally small, although, in Minnesota, the infant mortality rate for
married Medicaid mothers exceeded the infant mortality rate for
unmarried Medicaid mothers. In Minnesota and South Carolina. the
infant mortality rates were higher than avcrage for women less than 18
years of age. while in Florida and Texas. the infant mortality rates were
higher than average for women aged 35 years and older. As expected.
plurality is strongly related to infant mortality, with multiple births
considerably more likely to die within the first year of life than singleton
births.

Substantial differences in infant mortality rates are observed for women
who differed in the adequacy of prenatal care as measured by the Kessner



coefficients of prenatal WIC participation and prenatal care adequacy, are
presented in Table 5. Detailed probit results are presented in Appendix

A.
Prenatal WIC Prenatal WIC participation by 30 weeks gestation is generally
Participation associated with significant reductions in infant mortality with most of

the decline attributable to reductions in neonatal mortality. Specific
findings are the following:

* Infant Mortality. With the exception of Minnesota, the
predicted infant mortality rates with the WIC program are
roughly one-quarter to two-thirds the predicted infant
mortality rates without the WIC program. The estimated
reductions in infant mortality rates resulting from prenatal
WIC participation are 3.6 infant deaths per 1,000 live births in
Florida, 4.0 deaths per 1,000 live births in Texas, 8.4 deaths
per 1,000 live births in North Carolina, and 27.2 deaths per
1,000 live births in South Carolina.

¢ Neonatal Mortality. The proportionate reductions in neonatal
mortality rates for prenatal WIC participants are larger than
the proportionate reductions in infant mortality rates. With
the exception of Minnesota, the predicted neonatal mortality
rates with the WIC program are roughly one-sixth to two-
thirds the predicted neonatal mortality rates without the WIC
program. The estimated reductions in neonatal mortality rates
resulting from prenatal WIC participation are 2.3 neonatal
deaths per 1,000 live births in Florida, 3.0 in Texas, 7.3 in
North Carolina, and 19.9 in South Carolina.

*  Postneonatal Mortality. With the exception of South Carolina.
prenatal WIC participation is not significantly related to
postneonatal mortality. In South Carolina, the estimated
difference between postneonatal mortality rates with and
without WIC is 7.5. deaths per 1,000 live births, implying a 60
percent reduction in postnconatal mortality associated with
prenatal WIC participation. For the other states, the
differences in postneonatal mortality rates associated with WIC
are less than 1.3 and are not statistically significant.

20



Chapter

Il

Tl

CONTENTS

Page
ACKNOWLEDGMENTS ...... 2... cece cece eee eee eee eee ii
EXECUTIVE SUMMARY .... 2.0.00 eee cee eee eee eee v
INTRODUCTION 2.2... oon eee eee eee 1
WIC/MEDICAID STUDY FINDINGS ............0225202 eee ee eeee 1
WIC/MEDICAID DATABASE .........0 000 eee nn eeee 3
PROGRAM BACKGROUND AND FINDINGS FROM PREVIOUS
RESEARCH... 2.22.0 cece nett terete eee 5
BACKGROUND ON THE WIC AND MEDICAID PROGRAMS ........ 5
FINDINGS FROM THE LITERATURE ............ 00000 e eee eeee 6
ANALYSIS OF INFANT MORTALITY ........00.00000 cece eeee 10
DESCRIPTIVE ANALYSIS OF INFANT MORTALITY ............--. 10
MULTIVARIATE ANALYSIS OF INFANT MORTALITY ...........--- 17
Prenatal WIC Participation .. 2.2.0.0... eee cece eee eee eee 20
Adequacy of Prenatal Care 2... 2... eee 24
SUMMARY . 200. cece tee eee eee 24
REFERENCES ... 0... 2.2 e eens 27

APPENDIX A: ESTIMATED PROBIT COEFFICIENTS FOR
MODELS OF INFANT MORTALITY, NEO-
NATAL MORTALITY, AND POSTNEONATAL
MORALITY AMONG MEDICAID NEWBORNS

APPENDIX B: ESTIMATES FROM A STRUCTURAL MODEL

OF INFANT MORTALITY AND LOW BIRTH-
WEIGHT

iii



The earliest evaluation, Edozien et al. (1979), was a national
study of over 50,000 women, infants, and children at 19 WIC
projects in 14 states. Outcomes from clinical examinations
and laboratory samples collected between 1973 and 1976 for
current WIC participants were compared with similar measures
for new WIC enrollees at the time of their enrollment. The
primary study finding was that WIC participation during
pregnancy resulted in increased birthweight.

Kennedy et al. (1982) compared medical and nutritional
records collected between 1973 and 1978 for the births of 897
WIC participants with those of 400 pregnant women who were
either on WIC waiting lists or were receiving health services
at non-WIC facilities at nine sites in Massachusetts. WIC
participants had higher average birthweights than
nonparticipants (3,273 grams versus 3,136 grams).

Kotelchuck et al. (1984) examined 4,126 matched pairs of
births for WIC participants and nonparticipants from 1978
birth and death certificates and WIC program records in
Massachusetts. Prenatal WIC participation was associated with
a significant decrease in infant mortality, a lower percentage
of low birthweight newborns, and increased gestational age.

Metcoff ct al. (1985) examined a sample of 824 WIC-eligible
pregnant women who were attending prenatal clinics in
Oklahoma: half of the sample was assigned randomly to a WIC
treatment group and half to a control group. Average
newborn birthweight was higher for WIC participants than for
the control group (from 3,163 to 3,254 grams), based on
regression techniques which controlled for — selected
characteristics of the mother and her pregnancy.

Schramm (1985, 1986. and 1989). In three studies of
Medicaid-covered births in Missouri, prenatal ~=WIC
participation was associated with increased birthweight and a
lower percentage of Jow birthweight newborns.

Stockbauer (1986 and 1987). In the 1986 study the author
found mixed effects on birthweight, depending on which
comparison sample was used. However, he found that black
WIC participants consistently had newborns with higher



Determining an effect of prenatal WIC participation on infant mortality
is difficult. Few studies have examined infant mortality, while more have
examined measures that are related to infant mortality. Many WIC
evaluations are plagued by potentially serious methodological problems,
such as sample attrition or an inadequate comparison group methodology.
In addition, infant deaths are relatively infrequent events, requiring
researchers to have extremely large sample sizes to detect an effect if one
is present. With nearly 105,000 Medicaid births across the five study
States, the WIC-Medicaid database provides an opportunity to assess the
relationship between WIC participation during pregnancy and infant
mortality.



ACKNOWLEDGMENTS

This report was prepared by Mathematica Policy Research, Inc., under contract number 53-3198-
0-033 from the U.S. Department of Agriculture, Food and Nutrition Service, Office of Analysis and
Evaluation.

We gratefully acknowledge the support and helpful comments provided by Janet Tognetti, Jay
Hirschman, and Fran Zorn of the Food and Nutrition Service. We also thank several individuals
from Mathematica Policy Research who made important contributions to the study: Daisy Ewell.
Cara Hendricks, and Cindy Castro.

Barbara Devaney
Allen Schirm

SUGGESTED CITATION

Devaney, Barbara. and Allen Schirm. "Infant Mortality Among Medicaid Newborns in Five States:
The Effects of Prenatal WIC Participation.". U.S. Department of Agriculture, Food and
Nutrition Service, Office of Analysis and Evaluation, May 1993.



TABLE 4 ©

INFANT, NEONATAL, AND POSTNEONATAL MORTALITY
RATES AMONG MEDICAID NEWBORNS

Infant Neonatal Postneonatal
Mortality Mortality Mortality
Rate* Rate? Rate®

Florida

Total 10.4 61 43

WIC Participants by 30 Weeks 75 43 3.2

Nonparticipants by 30 Weeks 13.7 8.2 5.5
Minnesota

Total 13.3 6.2 7A

WIC Participants by 30 Weeks 12.1 5.7 6.4

Nonparticipants by 30 Weeks 15.3 7.2 8.1
North Carolina

Total 16.2 8.4 78

WIC Participants by 30 Weeks 12.1 5.2 6.9

Nonparticipants by 30 Weeks 23.7 14.0 9.7
South Carolina

Total 16.6 9.2 74

WIC Participants by 30 Weeks 8.7 3.7 5.0

Nonparticipants by 30 Weeks 36.9 23.1 13.8
Texas

Total 98 5.5 3

WIC Participants by 30 Weeks 6.5 3.5 3.0

Nonparticipants by 30 Weeks 11.4 6.7 47

Sourcr: WIC-Medicaid newborn database.

“Number of deaths to Medicaid infants less than one year of age per 1,000 live births. In Texas. the
rate refers to deaths of infants less than or equal to six months of age.

"Deaths to Medicaid infants within 28 days after birth per 1.000 live births.

“Deaths to Medicaid infants between 28 days and one year after birth per 1,000 live births. In Texas.
the postnconatal mortality rate refers to deaths of infants between 28 days after birth and less than

or equal to 6 months of age.



Contract No: 53-3198-0-033
Subcontract No: 1-524-4790
MPR Reference No: 7939-071

INFANT MORTALITY AMONG MEDICAID
NEWBORNS IN FIVE STATES: THE EFFECTS
OF PRENATAL WIC PARTICIPATION

May 1993

Authors:

Barbara Devaney
Allen Schirm

Submitted to: Submitted by:
U.S. Department of Agriculture Mathematica Policy Research, Inc.
Food and Nutrition Service P.O. Box 2393
Office of Analysis and Evaluation Princeton, NJ 08543-2393
3101 Park Center Drive, 2nd Floor (609) 799-3535 -

Alexandria, WA 22302
Under Subcontract to the Research
Project Officer: Dr. Janet Tognetti Triangle Institute
Task Leader: — Dr. Janet Togncetti



TABLE 7

ESTIMATED NUMBER OF INFANT DEATHS PREVENTED
BY PRENATAL WIC PARTICIPATION

Actual Number of Estimated Number of
Infant Deaths Infant Deaths Prevented*
Florida 374 114
Minnesota 156 0
North Carolina 336 174
South Carolina 196 320
Texas? 252 103

Source: WIC-Medicaid newborn database.

*Calculated by multiplying the estimated reduction in infant mortality rates due to prenatal WIC
participation by 30 weeks (Table 5) by the total number of Medicaid births during the study period
for each state (Appendix Table A.1).

"Deaths to infants less than or equal to 6 months of age.

26



TABLE 5

ESTIMATED EFFECTS OF PRENATAL WIC PARTICIPATION ON DEATH RATES OF MEDICAID NEWBORNS

Mortality Rate for Medicaid Newborns

Probit Coefficient Without WIC With WIC Difference
Florida
Infant Mortality Rate -140"° 19 83 3.6
Neonatal Mortality Rate 147" 69 46 23
Postneonatal Monality Rate -.105 5.0 37 13
Minnesota
Infant Mortality Rate -.036 14.0 128 12
Neonatal Mortality Rate 019 6.0 63 “3
Postneonatal Mortality Rate 073 81 6.6 15
North Carolina
Infant Mortality Rate -.208"° 213 12.9 84
Neonatal Mortality Rate 315" 128 5.5 73
Postneonatal Mortality Rate -.057 86 14 12
South Carolina
Infant Mortality Rate -587" 36.0 88 272
Neonatal Mortality Rate -.720"° 23.6 3.7 19.9
Postneonatal Mortality Rate 127 1S
Texas
Infant Montality Rate* -.169 + Wa 7 4.0
Neonatal Mortality Rate -.208 ** 66 3.6 3.0
Posinconatal Mortality Rate -.099 4.6 34 12
SouRcE: WIC-Medicaid newborn database
Nore: — Mortality rates are the number of deaths to Medicaid infants per 1.000 live births

“Refers to deaths to Medicaid infanis fess than or equal to 6 months of age

"(Significant at .05(.01) ievet

21



BACKGROUND
ON THE WIC
AND MEDICAID
PROGRAMS

Il. PROGRAM BACKGROUND AND FINDINGS FROM PREVIOUS
RESEARCH

In this chapter we provide (a) an overview of the WIC and Medicaid
programs, and (b) a discussion of findings from previous research on the
effect of prenatal WIC participation on infant mortality.

The Supplemental Feeding Program for Women, Infants, and Children
(WIC) was authorized by Congress in 1972 to provide nutritional
screening, food assistance, nutritional education, and health and social
service referrals for low-income pregnant and postpartum women, their
infants, and children up to age five. The major goal of the prenatal
component of the WIC program is to improve the nutritional status of
low-income pregnant women. Program eligibility depends on both
income and evidence of medical or dietary risks. States have the
option of setting income eligibility standards between 100 and 185
percent of the poverty level, provided that income eligibility is no lower
than that for free. or reduced-price health services. Nearly all states
have set income eligibility at 185 percent of the poverty level, although,
in 1987, a few locations in Texas, Florida, and North Carolina may have
used a lower income eligibility criterion. Medical risks include anemia,
extremes of leanness or obesity. maternal age, or a poor pregnancy
history. Dictary risks are primarily poor dietary patterns.

The WIC program has become an important part of prenatal care
provided to low-income pregnant women by public health clinics.
Nationwide, the WIC program has grown from a $750 million program
that served 2 million women, infants, and children per month in 1980 to
a $2.6 billion program that served an estimated 5.3 million women. infants.
and children per month in 1992. During fiscal year 1987, the WIC grants
in the five study states ranged from a $26 million program that served an
average of 56.04) per month in Minnesota to a $112 million program that
served 226,000 persons per month in Texas.

The organization of program operations at the local level varies greatly,
but for pregnant women it works approximately as follows. When a
woman learns about the program and applies at a local WIC office, she
is screened to determine whether she meets the income criterion and onc



birthweights than black nonparticipants. The study was based
on a comparison of WIC participants and several different
groups of nonparticipants. In the 1987 study Stockbauer
found that relative to nonparticipants, WIC participants had a
lower percentage of low birthweight newborns. This study
compared matched pairs of WIC and non-WIC births. Both
studies found that at least 7 months of WIC participation were
required to observe improved birthweight outcomes.

. Rush (1986) compared longitudinal data on 5,205 prenatal
WIC participants and 1,358 non-WIC registrants at prenatal
clinics selected from 174 WIC sites and 55 clinics across the
country. The primary findings concerning the effects of
prenatal WIC participation on measures or correlates of infant
mortality are: no statistically significant effect on newborn
birthweight; increased birthweight with better WIC program
quality; no statistically significant effect on gestational age; and
a Jower incidence of fetal death and low birthweight of
appreciable but not significant magnitude.

These evaluations shared a number of features. Each examined the ability
of WIC participation to increase birthweight. Low birthweight is known
to predict subsequent short- and long-term health problems in newborns,
such as respiratory difficulties and developmental disabilities (Institute of
Medicine, 1985). In addition, low birthweight is a primary determinant of
infant mortality and morbidity (McCormick 1985). Neonatal and infant
mortality rates are considerably higher for low-birthweight newborns
relative to newborns that are not low birthweight. One study found that,
relative to normal-birthweight newborns, low-birthweight newborns were
40 times more likely to die in the neonatal period (Shapiro et al. 1980).

The General Accounting Office (GAO) conducted a review of WIC
evaluations in 1984 to assess the effectiveness of the WIC program in
reducing the likelihood of adverse pregnancy outcomes. Because of the
methodological limitations of these studies, GAO felt that there was not
sufficient information to make a conclusive judgement of the effectiveness
of the WIC program. Most importantly for this analysis of infant
mortality, while GAO concluded that WIC evaluation studies gave some
support for the ability of the WIC program to increase birthweight, they
found substantially less data to support claims that the WIC program
decreased fetal and nconatal deaths.