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Testimony on Infant Mortality and Prenatal Care by James S. Marks, M.D., M.P.H.
National Center for Chronic Disease
Prevention and Health Promotion
Centers for Disease Control and Prevention
Public Health Service
U.S. Department of Health and Human Services
Before the House Committee on Government Reform and Oversight, Subcommittee on Human Resources and Intergovernmental Relations
March 13,1997
Good Morning, I am James Marks, M.D., Director of the National Center for Chronic Disease
Prevention and Health Promotion, Centers for Disease Control and Prevention (CDC). I am
accompanied today by Mary Anne Freedman, Director of the Division of Vital Statistics in
CDC's National Center for Health Statistics. I am pleased to be here to discuss some of our
agency's activities related to infant mortality and prenatal care, including the National Vital
Statistics System. In response to the Subcommittee's request, I will give a brief overview of the
infant mortality and birth-weight data maintained by CDC, discuss the timeliness and accuracy
of the data, and describe some of CDC's activities in the area of infant health and mortality.
The infant mortality rate in the United States has declined steadily over the last quarter century,
reaching 7.5 deaths per 1,000 live births in 1995 (based on preliminary data) -- the lowest rate
ever recorded in the United States. However, the relatively poor international ranking of the
United States in infant mortality (22nd in 1992) and the large differential in infant mortality
among the United States' population subgroups present cause for concern. Approximately
30,000 infants die in the United States each year. The leading causes of death for infants are
birth defects, disorders relating to prematurity and low birth weight, and sudden infant death
syndrome.
I. NATIONAL VITAL STATISTICS SYSTEM
The National Vital Statistics System - maintained by CDC's National Center for Health
Statistics - is the source for the Nation's official vital statistics. The registration of vital events,
including births and deaths is a State function governed by State laws. Thus, the Nation's vital
statistics are based on State vital statistics records and are generated through State-operated
registration systems. CDC collaborates with the States to develop standard forms for data
collection and model procedures to ensure uniform registration of the vital events. CDC shares
the costs incurred by the States in providing vital statistics data for national use.
Detailed annual data on births and deaths are available for the United States as a whole, and for
States, counties, and cities of greater than 100,000 population. In addition to maintaining data
files on births and deaths, CDC maintains files which "link" birth and infant death data. These
files link information from the birth certificate (such as birth-weight, prenatal care, and mother's
age) and the death certificate (such as cause and age of death), and enable us to explore the
complex relationships between infant deaths and factors present at birth. The linked files are
particularly useful in examining racial and ethnic disparities in infant mortality.
Existing data on low birth-weight and infant mortality are highly accurate. For the 1991 birth
cohort, for example, CDC and the States were able to match 97.7 percent of all infant death
records to their corresponding birth certificates. In addition, data timeliness is improving
dramatically as a result of electronic collection and transmission of data. CDC, thus is now
able to publish birth and death rates more timely. In October 1996, CDC released preliminary
data for calendar year 1995, including preliminary infant mortality rates by cause of death and
race. This represents an almost 12 month improvement over previous data releases. CDC is
also accelerating the publication schedule for the linked birth and infant death files, which
provide valuable information on the causes of infant mortality. Release of the 1995 linked file is
expected in September 1997.
II. CDC INFANT HEALTH AND MORTALITY ACTIVITIES
Numerous activities and research projects are underway at CDC to promote infant health and
assist in the prevention of infant mortality and morbidity. The following provide examples:
Analyses of Vital Statistics Data: The data maintained by the National Vital Statistics System is
critical to many of the analyses CDC conducts to further understanding of the factors affecting
infant mortality, low birth-weight, and related indicators of pregnancy outcome. Let me
summarize two examples:
- Data by Cities: CDC has developed an information system to increase access to
comparative vital statistics on prenatal care, low birth-weight and infant mortality in cities
in the United States. This system facilitates the comparison of maternal and child health
indicators among cities. While the maternal and child health status of cities in general is
lower than the U.S. as a whole, it is important to realize that there is much inter-city
variation in measures of maternal and child health. For instance:
-
One measure of maternal and child health is early prenatal care - defined as
having the initial prenatal visit within the first three months of pregnancy. In 1994, the
most recent year for which final data are available, approximately 80 percent of all U.S.
women received early prenatal care (this represents a 1 percent increase over the previous
year). Among the 23 largest U.S. cities (1990 Census population >500,000), only about
50 percent of women received early prenatal care in New York City, El Paso, and
Washington, DC. Conversely, more than 80 percent of women in Columbus, San
Francisco, and Boston received early prenatal care.
- Similarly, inter-city variation also occurs with measures of infant health, such as
low-birth-weight (birth-weight <2500 grams, or approximately 5 � pounds). In 1994, 7.3
percent of infants were born with low-birth-weight in the U.S.. Among the large U.S. cities, the
percentage of infants born with low-birth-weight was as low as 6 percent in Seattle, San Diego,
and San Jose, and over 13 percent in Memphis, Baltimore, Detroit, and Washington, DC.
Racial Ethnic Variation: The main contributors to the excess mortality among
African-American infants are the high rate of very low birth-weight (<1500g) and the excess
rate of postneonatal mortality among normal birth-weight babies. Although very
low birth-weight infants represent a tiny fraction of all live births in the United States (2.3
percent of singleton births among African-Americans and 0.8 percent among whites),
they account for almost two-thirds of the disparity in infant mortality between
African-Americans and whites. The majority of all very low birth-weight infants are born
as a result of a preterm delivery. Moreover, the more premature an infant is, the more
difficult medical treatment becomes.
Another 25 percent of the gap in infant mortality between African-Americans and whites
derives from deaths among normal birth-weight babies, many of whom survive the first 28
days of life but die during the postneonatal period. Patterns of postneonatal mortality
suggested that with a few exceptions, such as certain congenital birth defects, excess
deaths among normal birth-weight black infants generally resulted from potentially
preventable causes such as infections, injuries, and sudden infant death syndrome
(SIDS).
The infant mortality and birth-weight data were also used to study the experience of
African- American infants born to families in which women are college educated and
presumably have occupational stability, health insurance, access to services, and early
entry into care. African-American and white infants born t o college educated parents
had similar infant mortality rates for many causes, including sudden infant death
syndrome (SIDS), injuries, and respiratory diseases. However, among infants born to this
highly educated group of parents, those born to African-American college graduates had
an 80 percent higher risk of dying during their first year of life than babies born to white
college graduates. This excess was related most notably to a three times higher rate of
very low birth-weight in the African-American than in the white college educated
population. Thus, the disparity in the very low birth-weight rate for infants of
African-American college-educated parents is almost as large for the general population.
The Maternal and Child Health Epidemiology Program (MCHEP): The Maternal
and Child Health Epidemiology Program (MCBEP), a collaborative effort between CDC
and the 5 Health Resources and Services Administration (HRSA), provides support to
State maternal and child health (MCH) programs. Its primary objectives are (1) to assist
States in identifying and collecting the data needed to assess and protect the health of
mothers and infants, (2) to conduct epidemiologic analyses of maternal and infant health
service and policy issues essential for State program planning, policy development and
priority setting, and (3) to support State efforts to use information effectively to make
decisions about the health of mothers and infants.
Numerous examples exist to document the improvement in programs and changes in
policy that resulted from this epidemiologic support. Through the MCHEP program, for
example, the State of Georgia evaluated the efficacy of prenatal care case management
funded by Medicaid and found that it does get high risk women into care earlier. This
evaluation influenced the state to continue providing case management services.
Pregnancy Risk Assessment Monitoring Systems (PRAMS): PRAMS is a
surveillance system designed to identify and monitor selected maternal behaviors and
experiences that occur before, during, and after pregnancy. In particular, PRAMS was
designed to supplement data from vital records and to generate data for planning and
assessing perinatal health programs in participating States (presently 15 States). States
select a sample of mothers who are asked about behaviors and experiences such as access
to, and use of, prenatal and infant care, alcohol use, smoking, and violence during
pregnancy. These data are meant to be used to enhance understanding of maternal risk
factors and their relationship with adverse pregnancy outcomes and aid in the
development and assessment of programs designed to identify high-risk pregnancies and
reduce adverse outcomes, including low birth-weight and infant mortality. According to
the PRAMS group in Oklahoma, "Half of all women with Medicaid coverage who had
their first prenatal care, visit after the first trimester indicated that they began care as early
as they wanted, nearly twice the rate among non-Medicaid women. Awareness of the
importance of prenatal care remains a barrier to received early care, particularly among
women with Medicaid coverage."
Prenatal Care: Early initiation of prenatal care is believed to promote healthy
pregnancy outcomes. However, in the United States in 1994, approximately 20 percent
of the infants were delivered to women who had received prenatal care after the first
trimester of pregnancy or received no prenatal care at all. Wide differences exist in rates
of delayed initiation of prenatal care by State, county, ward, and neighborhood.
Moreover, studies have demonstrated an association between delayed prenatal care
initiation and various demographic characteristics. Research aimed at identifying and
understanding the barriers to early prenatal care initiation will assist in developing
strategies to alleviate these barriers. Presently, CDC is conducting research to explore the
reasons for the delay in initiating early prenatal care, using both PRAMS data and
national and State-based vital statistics data.
Prenatal Smoking Cessation (PSC): Smoking during pregnancy has been
identified as the most important potentially preventable cause of low birth-weight in the
United States. It is estimated that perhaps 25 percent of low birth-weight in the United
States can be attributed to maternal smoking. The purpose of CDC's Prenatal Smoking
Cessation program is to develop and enhance the capacity of maternal and child health
programs to reduce the effects of smoking among women of reproductive age and their
families. Since 1986, CDC has provided funding and technical assistance to State health
departments in the development, implementation and evaluation of prenatal smoking
cessation interventions. Since 1993, CDC also has collaborated with the Association of
Maternal and Child Health Programs (AMCBP) to promote smoking cessation during
pregnancy.
Birth Defects: Birth defects are the leading cause of infant mortality in the United
States and the primary cause of nearly 7,000 or 20 percent of all infant deaths each year.
The commonly held belief that birth defects, developmental disabilities, and genetic
diseases are rare occurrences that cannot be prevented is far from accurate. Each year,
factors in the periconceptional and prenatal environment result in major birth defects that
affect 120,000 babies. Already, we know the causes of about 25 percent of these birth
defects, and as a result, prevention is possible in some cases. CDC's surveillance and
epidemiologic capabilities have enabled us to take a leadership role in monitoring trends
in birth defects, developmental disabilities, and genetic diseases; in linking these health
outcomes with the factors in the environment that increase risk; and in identifying
effective means of reducing that risk.
CDC has established Centers for Birth Defects Prevention Research in 6 States which
have initiated unique national collaborative research into the causes of birth defects. The
causes of about 75 percent of all birth defects are unknown. The role of environmental
pollutants, drugs, specific behaviors, or genetic susceptibilities in causing birth defects,
developmental disabilities, or other adverse reproductive outcomes is being explored.
These new Centers will accelerate the process of finding the causes and risk factors for
birth defects.
CDC's research and efforts on folic acid is an excellent example of CDC's working with
its partners on birth defects prevention. In 1991, research by CDC and others showed
that the vitamin, folic acid, could prevent 50-70 percent of the U.S. cases of neural tube
defects, spina bifida and anencephaly. Each year in the United States, 2,000 cases of
spina bifida and anencephaly can be prevented by consumption of adequate amounts of
folic acid by women of childbearing age. CDC's efforts contributed significantly to the
Food and Drug Administration's decision to require low-level fortification of the food
supply in order to prevent neural tube defects. CDC also works to increase the
percentage of women consuming folic acid supplements in order to prevent neural tube
defects, and provides advice and technical assistance to many states that are initiating
folic acid programs.
Sudden Infant Death Syndrome (SEDS): In the United States, 4,000 to 5,000
infant deaths occur due to SIDS annually. SIDS is the leading cause of infant deaths
between 1 month and 1 year of age and accounts for a third of these deaths. Although the
cause (s) of SIDS is unknown, many modifiable risk factors have been identified,
including prone (face down) sleeping position, in utero and environmental tobacco
exposure, not breast-feeding, and soft bedding.
CDC has several major activities related to SIDS. For example, CDC plays a key role in
SIDS mortality surveillance and monitoring of changes in risk factors over time (tobacco
use, breast-feeding, prone sleep). CDC also has issued the first national guidelines for
death scene investigation of SIDS, which are designed to help State and local medical
examiners and coroners to conduct a standardized and uniform investigation of SIDS. In
addition, in collaboration with NIH-NICHD, CDC is supporting two research projects in
Chicago and the Aberdeen Area of the Indian Health Service designed to examine the
association between social, environmental, and medical risk factors and SIDS.
Preterm Delivery: Preterm delivery, the birth of an infant before completion of 37
weeks of gestation, is one of the predominant proximate causes of low birth-weight and,
together with low birth-weight, is the third leading cause of infant mortality in the United
States. The percent of preterm births has risen steadily from 9.4 in 1981 to 11.0 in 1994.
African-American women experience twice the risk of preterm delivery as white women.
The reason for the disparity in preterm delivery between African-American and white
women remain unexplained. Therefore, CDC has begun to examine psychological,
social, cultural, and environmental factors that may contribute to pretense delivery. In
particular, CDC is supporting community-based prevention research to improve
understanding of both risk and protective factors influencing maternal health and
pregnancy outcomes. In addition, because high levels of exposure to such factors as
stressful life experiences put African-American women at increased risk for adverse
reproductive outcomes, CDC is examining the validity and reliability of stressful life
event scales in African-American women.
III. CONCLUSION
Continued progress in reducing the Nation's infant mortality rate and eliminating the racial and
ethnic differences in pregnancy outcomes will occur if the national, State and local
commitment to improving birth outcomes and maintaining healthy infants also continues. It is
increasingly clear that infant mortality is a problem that needs community-based as well as
medical interventions. The Healthy Start demonstration program and the complementary work
that CDC is engaged in on community-based prevention research are both innovative
approaches that contribute to reducing infant mortality in communities that still have an excess
burden of infant deaths. CDC will continue to work with its partners - federal, state, local and
private to strengthen surveillance efforts, to conduct prevention research, and to disseminate
information about what works to prevent infant mortality.
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