Does the 39-week rule apply with multiple cesareans?

“Term” delivery is defined as 39 weeks 0 days, according to the American College of Obstetricians and Gynecologists. For women with repeat cesareans, that timing may not result in the best outcomes, say investigators from the University of Texas Medical School at Houston.

Presenting at the Society for Maternal-Fetal Medicine’s 34^th annual meeting, the Pregnancy Meeting, the researchers concluded that 38 weeks 0 days to 38 weeks 6 days may be optimal for delivery of women with two previous cesareans and 37 weeks 6 days may be optimal for women with ≥3 previous cesareans.  The findings were based on analysis of data from 6,435 women with ≥2 previous cesarean deliveries who achieved ≥37 weeks 0 days.

Excluded from the study were women with underlying medical or obstetrical conditions that dictated delivery before 39 weeks. Risks of adverse maternal (e.g. transfusion, hysterectomy, operative injury) and/or perinatal outcomes (e.g. respiratory distress syndrome, necrotizing enterocolitis, death) were calculated based on timing of delivery vs. those women who remained undelivered.

Complication rates were significantly different across gestational ages for both maternal (P<0.005) and neonatal outcomes (P<0.005). At 38 to 39 weeks, risk of adverse maternal outcomes was three times higher, with a concomitant increase in risk of adverse perinatal outcomes, in women with two prior cesarean deliveries. At 37 to 38 weeks, risk of maternal complications was four times higher in women with ≥3 cesarean deliveries. 

Commentary by Contemporary OB/GYN board member Joshua A Copel, MD:

"The pendulum will swing a few more times before we find the proper balance on timing of elective repeat cesareans. On the one hand, it’s clear that neonatal complications are more common for babies delivered electively before 39 weeks 0 days. On the other hand, there is a small risk of stillbirth for ANY pregnancy at ANY time. Women who have had 2 or more prior cesareans and who go into labor spontaneously have a small risk of uterine rupture due to spontaneous onset of labor, and the more previous cesareans a woman has had, the higher the risk of rupture. It is, therefore, a logical question to ask whether it is safer to deliver earlier with more prior cesareans. This provocative study suggests that we may need to reassess the optimal timing of elective repeat cesarean delivery in this group because the risk of complications from delay may outweigh the risk of prematurity complications. In other words, we may end up treating these women like those with a prior classical incision or a placenta previa, with a lower optimal gestational age for delivery."

To get weekly advice for today's Ob/Gyn, subscribe to the Contemporary Ob/Gyn Special Delivery.