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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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