DALLAS – Compared with expectant management, labor induction for cases involving a suspected large-for-dates fetus was associated with a threefold reduction in the risk of neonatal trauma and an improved likelihood of spontaneous vaginal birth in a randomized controlled trial involving 817 women.
Induction did not increase the cesarean section rate, compared with expectant management, but neonates in the induction group did have a higher rate of severe icterus, Dr. Michel Boulvain reported at the annual meeting of the Society for Maternal-Fetal Medicine.
The rates of neonatal trauma were 2.2% in the 407 women who were randomized to be induced, and 6.6% in 410 controls who underwent expectant management (relative risk, 0.34). The likelihood of a spontaneous vaginal delivery also was significantly higher in the induction group (RR, 1.14), said Dr. Boulvain of University Hospitals of Geneva, Switzerland.
The cesarean section rates in the induction and expectant management groups were 28% and 31.7%, respectively.
Women in the induction group delivered a mean of 9 days earlier, and birth weight in that group was 300 g less than in the expectant management group.
The study was conducted in collaboration with 20 teaching hospitals that are members of the Research Group in Obstetrics and Gynecology (GROG) in France, Switzerland, and Belgium. Study participants were women who underwent a clinical screening at 36-38 weeks’ gestation indicating an estimated fetal weight above the 90th percentile, and who then underwent sonography indicating an estimated fetal weight above the 95th percentile. Those randomized to induction were induced within 3 days.
Women with diabetes treated with insulin, and those with a history of cesarean section or shoulder dystocia were excluded.
Baseline characteristics were similar in the induction and expectant management groups, and no differences were seen with respect to very severe outcomes, Dr. Boulvain said.
The findings with respect to the individual outcomes from the composite neonatal trauma outcome – such as shoulder dystocia, brachial plexus injury, and fractures – each were improved in the induction group, compared with the expectant management group, which is encouraging, he noted.
The increase in the rate of icterus, however, is disturbing, and might be explained by fact that the induction group delivered more than a week earlier, or by increased attention to that outcome in the induction group, he said.
It could also be a direct effect of the oxytocin, he suggested.
Nonetheless, the conclusion of the findings is that induction of labor at 37-38 weeks’ gestation when estimated fetal weight is above the 95th percentile decreases risk of outcomes such as shoulder dystocia and fracture without increasing the risk of cesarean section, and increases the likelihood of spontaneous vaginal delivery, he said.
He added that decisions about management should be made with consideration of the characteristic and preference of the patient, keeping in mind that prior cesarean section and other conditions can preclude induction, and also keeping in mind that icterus is a potential concern.
Dr. Boulvain said he had no relevant financial disclosures.