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By Steven G. Gabbe, MD
Infant mortality, the number of infant deaths under 1 year of age per 1000 live births, is a singularly important indicator of the health of a population. Each year, approximately 35,000 infant deaths occur in the United States. This review focuses on the causes of infant mortality in the United States and proposes possible solutions to reduce this loss of life.
The following case history illustrates many of the factors that contribute to the high rate of infant mortality in United States.
Mary is a 16-year-old black high school student, pregnant for the first time. She and her boyfriend have been using withdrawal as a method of contraception. Mary says she smokes a pack of cigarettes every day and drinks alcohol and uses marijuana at weekend parties. She tried to hide her pregnancy and did not receive prenatal care. At approximately 30 weeks' gestation, Mary was found in her bedroom seizing. She was brought to the hospital, where eclampsia was diagnosed. A cesarean delivery was performed. Her infant weighed 1000 g, suffered from severe respiratory distress syndrome (RDS), and had an intraventricular hemorrhage. The child died at 6 months of age due to sudden infant death syndrome (SIDS).
Many of the factors that contribute to infant mortality in the United States are evident in this story, including teenage pregnancy, unintended pregnancy, smoking and substance abuse, lack of prenatal care, a serious medical complication of pregnancy, premature delivery, RDS, and SIDS.
The infant mortality rate (IMR) in this country has steadily declined from 20/1000 in 1970 to nearly 15/1000 in 1980, and to 9.2/1000 in 1990. In 1993, the IMR in the United States was 8.5/1000 births. However, the United States ranks below 21 other industrialized countries in infant mortality. The highest infant mortality rate documented in 1992 was in the District of Columbia, which had a rate of 17.4/1000, while the lowest was observed in New Hampshire with a rate of just 5.6/1000. As seen in Table 1, Japan has the lowest IMR at 4.5/1000. Canada stands in eighth place, with an IMR of 6.1/1000, and England and Wales are at thirteenth with a rate of 6.6/1000.
What is it about these countries that may be associated with lower IMRs? Clearly, the most important factor associated with infant mortality is poverty and its relationship to access to health care and nutrition. In general, these countries have lower rates of poverty and no financial barriers to health care. These countries actively support prenatal care, in some cases providing financial incentives for women to attend prenatal care. Their health care systems support home visits by health care providers and easy access to family planning.
|*National Center for Health Statistics|
The leading causes of infant mortality in the United States include birth defects and problems related to premature birth. (See Table 2.) Birth defects have been the leading cause of infant mortality for more than two decades. Seventy percent of these deaths occur in the first month of life. Cardiac defects are the most common fatal malformations and, as a group, are responsible for approximately one-third of all infant deaths due to malformations. Neural-tube defects are the second most common cause of infant mortality due to congenital malformations. As seen in Table 2, SIDS, prematurity, low birth weight (LBW), and RDS, when combined, are responsible for 27% of all infant mortality. Most of these deaths occur in the first 28 days of life. The percentage of LBW infants (infants weighing < 2500 g at birth) in the United States increased slightly to 7.2% in 1993 and probably contributed to the higher IMR due to prematurity and LBW in 1993. The LBW rate among black women remains twice that of white women at 13.3% and is certainly responsible for the higher IMR of 16.5/1,000 seen in the black population. Of note, between 1983 and 1993, multiple births increased 24%, and births of infants less than 1000 g increased 14%, probably due to assisted reproductive technologies. The fall in infant mortality due to RDS may be attributed to the use of surfactant and other advances in care of the premature infant.
|1. Birth defects||178||-2.7%|
|5. Maternal compliations||34||-6.4%|
*Info-Share, March of Dimes Perinatal Data Center, Office of the Medical Director, April 1996.
What can be done to reduce infant mortality in the United States? First, the problem must be recognized. The IMR in each state, city, and town should be examined and the highest risk populations identified. Prepregnancy care should be encouraged. This process can effectively address many contributors to infant mortality through cessation of smoking and substance abuse, care of medical complications such as diabetes mellitus, attention to important psychosocial issues, such as domestic violence, and counseling regarding family planning. Women should be encouraged to take 0.4 mg of folic acid daily starting three months before conception and continuing through the first trimester to reduce the risks of having a child with a neural-tube defect. During prepregnancy counseling, the importance of prenatal care should be stressed. It is important to help the patient identify a site where she can easily obtain prenatal care. In the United States, the Healthy People 2000 goal is to reduce the IMR to 7/1000 or less by the end of this century. While it is unlikely that that target will be reached, public health measures as well as continued research into the important causes of infant mortality can help reduce this excessive loss of life.
Child Health USA 1995, U.S. Department of Health and Human Services, Public Health Service, Health Resources and Services Administration, Maternal and Child Health Bureau, September 1996.
March of Dimes. Statistics for Healthier Mothers and Babies. White Plains, New York: 1993.