Full-term pregnancy halves risk of newborn death

Babies delivered at full term (at least 39 weeks) are only half as likely to die as infants delivered at 37 weeks, according to a study from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, the March of Dimes, and the US Food and Drug Administration.

Researchers analyzed 46,329,018 live singleton births using period-linked birth and infant death data from 1995 to 2006 from the National Center for Health Statistics. Although overall mortality rates for early term and full-term births decreased between 1995 and 2006, early term infants had higher infant and neonatal mortality rates than full-term infants for every year during that period. In 2006, babies born at 37 weeks had a mortality rate of 3.9 per 1,000 live births compared with 1.9 per 1,000 for babies born at 40 weeks.

The study appears in the June issue of Obstetrics & Gynecology (2011;117[6]:1279-1287).

Although mortality generally trended downward between 37 and 40 weeks for infants of all racial and ethnic groups, the researchers note a “concerning racial and ethnic disparity in rates and trends.” Mortality rates for “non-Hispanic black babies born at 37 or 38 weeks of pregnancy remain unacceptably higher than other racial and ethnic groups,” says lead author Uma M Reddy, MD.

Both early term and full-term non-Hispanic black infants had neonatal mortality rates 40% higher than white infants. Postnatal death rates were 80% higher.

“Our results indicate that intervention programs are needed for this high-risk group, as is additional research to understand why non-Hispanic black infants are less likely than other groups to live to celebrate their first birthday,” Reddy says.