Research shows that babies do best when they are born during weeks 39 and 40. A pregnancy is considered full term at 39 weeks, and the due date is 40 weeks. Sometimes a woman with a healthy pregnancy will ask for labor to be induced at 39 or 40 weeks.
Previous studies suggested that inducing labor may increase the risk of needing a cesarean delivery or C-section, which is major surgery. It takes longer to recover from surgery than a vaginal birth. Also, having surgery may increase a woman’s risk of having a C-section in future pregnancies.
NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) funded a large national study to examine the risks and benefits of a woman choosing labor induction at 39 weeks, rather than waiting for labor to begin naturally. The study was led by Dr. William Grobman of Northwestern University. Results were published on August 9, 2018, in the New England Journal of Medicine.
More than 6,000 healthy women who were pregnant for the first time were enrolled. The investigators randomly assigned about half of the women to have their labor induced during week 39. The other half waited for labor to begin naturally. For women who waited for natural labor and had problems, the health care team intervened with delivery, either by induction or C-section.
The team compared serious health problems and deaths in the two groups of babies. Serious health problems included needing help with breathing, having a seizure, or getting an infection. There was no significant difference between the groups in serious health problems or deaths (4.3% for induced labor and 5.4% for waiting). This finding suggests that induced labor doesn’t put babies at increased risk of health problems.
The researchers did find a significant difference in the proportions of women needing a cesarean delivery (18.6% for induced labor and 22.2% for waiting). Also, the proportion of women with blood pressure disorders was significantly lower in those who were induced (9.1%) than those who waited for natural labor (14.1%).
“Prior to this study, there was concern that induction of labor would increase the chance of cesarean delivery,” says Dr. Uma M. Reddy, an NICHD medical officer and coauthor of the study. “Our analysis suggests that elective induction at 39 weeks is associated with a lower rate of cesarean delivery and does not increase the risk of major complications for newborns.”
“Induction at 39 weeks should not be routine for every woman, but it’s important to talk with their provider and decide if they want to be induced and when,” Grobman says.