Infants Delivered by Certified Nurse Midwives have Lower Mortality Rates

National Center for Health Statistics Press Office
May 19, 1998

The first study known to examine the infant mortality risks for all babies delivered by certified nurse midwives in the United States shows excellent birth outcomes for these midwife-attended deliveries. The new study from the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC), published in the May (1998) issue of the "Journal of Epidemiology and Community Health," examined all single, vaginal births in the United States in 1991 delivered at 35 to 43 weeks of gestation by either physicians or certified nurse midwives.

After controlling for a wide variety of social and medical risk factors, the risk of experiencing an infant death was 19 percent lower for births attended by certified nurse midwives than for births attended by physicians. The risk of neonatal mortality (an infant death occurring in the first 28 days of life) was 33 percent lower, and the risk of delivering a low birthweight infant was 31 percent lower. Mean birthweight was 37 grams heavier for the certified nurse midwife attended than for the physician attended births. Low birthweight is a major predictor of infant mortality, subsequent disease, or developmental disabilities.

Certified nurse midwives attended a greater proportion of women who are at higher risk for poor birth outcome: African Americans, American Indians, teenagers, unmarried women, and those with less than a high school education. Physicians attended a slightly higher proportion of births with medical complications. However, birth outcomes for certified nurse midwives were better even after sociodemographic and medical risk factors were controlled for statistical analyses.

The differences in birth outcomes between certified nurse midwife and physician attended births may be explained in part by differences in prenatal, labor, and delivery care practices. Other studies have shown that certified nurse midwives generally spend more time with patients during prenatal visits and put more emphasis on patient counseling and education, and providing emotional support. Most certified nurse midwives are with their patients on a one-on-one basis during the entire labor and delivery process providing patient care and emotional support, in contrast with physician's care, which is more often episodic.

The proportion of births attended by certified nurse midwives in the United States is growing. In 1995, 6 percent of all U.S. births were delivered by certified nurse midwives, compared to 3 percent in 1989.

"Midwifery care, social and medical risk factors and birth outcomes in the USA," by Marian F. MacDorman and Gopal K. Singh is based on information from the death certificate for each infant under 1 year of age who died in 1991.

Birth and death records are maintained by State vital statistics offices and reported to NCHS/CDC through the National Vital Statistics System.

Some experts, however, warn that the research may be misleading.

"Midwives should always have better delivery outcomes because they are mandated by rules and regulations to turn over to an obstetrician any mother who develops a medical complication during pregnancy or delivery," said Dr. Ruth Lawrence, professor of pediatrics and obstetrics and gynecology at the University of Rochester. "Therefore, this research is slightly misleading. It is true, however, that midwives do an excellent job when they work with low-income and adolescent mothers and provide them with good support. In these instances, midwives can indeed have very excellent delivery outcomes."