Infant and neonatal mortality rates are higher with voluntary caesarean sections than with vaginal births, according to a study published in the September issue of the journal Birth: Issues in Perinatal Care, the New York Times reports.
Marian MacDorman, a CDC statistician, and colleagues examined data on 5,762,037 live births and 11,897 infant deaths from 1998 through 2001 in the U.S. to assess the risk of death for infants and neonates as a result of voluntary c-sections among women with no indicated complications. Higher mortality rates associated with c-section deliveries previously have been attributed to higher risk factors of the pregnant woman, the Times reports. According to the researchers, the study is the first of its kind to assess the risks of c-section delivery among women who voluntarily undergo the procedure. C-section births in the U.S. increased from 20.7% in 1996 to 29.1% in 2004 (Bakalar, New York Times, 9/5).
The study finds that neonatal and infant mortality rates were 1.77 per 1,000 infants delivered via voluntary c-section, compared with 0.62 per 1,000 infants delivered vaginally (MacDorman et al., Birth: Issues in Perinatal Care, 9/5). Researchers said that the higher mortality rates among voluntary c-section deliveries could be because vaginal labor releases hormones that promote healthy lung functioning. According to the researchers, the physical compression of the infants during vaginal birth helps to eliminate fluid from the lungs and prepares the infants to breathe. Researchers also suggested that possible cuts to the infants during a c-section or delayed establishment of breast-feeding might account for the increased death rate. The researchers said the study is limited by the accuracy of medical data reported on birth certificates. Michael Malloy, a co-author of the article and a professor of pediatrics at the University of Texas Medical Branch, said, "Despite attempts to control for a number of factors that might have accounted for a greater risk in mortality associated with c-sections, we continued to observe enough risk to prompt concern," adding, "When obstetricians review this information, perhaps it will promote greater discussion within the obstetrical community about the pros and cons of offering c-sections for convenience and promote more research into understanding why this increased risk persists." According to MacDorman, "Neonatal deaths are rare for low-risk women -- on the order of about one death per 1,000 live births -- but even after we adjusted for socioeconomic and medical risk factors, the difference persisted" (New York Times, 9/5).