Women choosing repeat cesarean deliveries at 37 or 38 weeks gestation, without a medical or obstetric indication, are up to two times more likely to have a baby with serious complications, including respiratory distress resulting in mechanical ventilation and NICU admission.

Tita

“The cesarean rate in the United States has risen dramatically, from 20.7 percent in 1996 to 31.1 percent in 2006,” Tita said. “A major reason is the decline in attempted vaginal births after cesarean. Because elective cesareans can be scheduled to accommodate patient and physician convenience, there is a risk that they may be performed earlier than is appropriate.

“We knew from previous small studies that infants born before 39 weeks gestation are at increased risk for respiratory distress,” he said. “Because nearly 40 percent of the cesareans performed in the United States each year are repeat procedures, we undertook this large study to describe the timing of elective repeat cesareans and assess its relationship with the risk of various adverse neonatal outcomes.”

In the study population, babies born at 37 weeks were two times more likely to suffer with conditions common to babies born too soon, and at 38 weeks, they were one-and-a-half times more likely.

Tita said these findings, along with other studies, underscore the importance of not delivering a baby before 39 weeks for the sake of convenience. “Unfortunately, these early deliveries are associated with a preventable increase in neonatal morbidity and NICU admissions, which carry a high personal and economic cost,” he said. “These findings support recommendations to delay elective delivery until 39 weeks gestation and should be helpful in counseling women on the necessity of waiting to deliver.”