Clinical Pearls & Morning Reports
Published August 8, 2018
Grobman et al. conducted the ARRIVE trial (A Randomized Trial of Induction Versus Expectant Management) to test the hypothesis that elective induction of labor at 39 weeks would result in a lower risk of a composite outcome of perinatal death or severe neonatal complications than expectant management among low-risk nulliparous women. Read the latest NEJM Original Article here.
Q: Why has elective labor induction been generally avoided for gestations between 39 weeks 0 days and 40 weeks 6 days?
A: When gestation is between 39 weeks 0 days and 40 weeks 6 days, common practice has been to avoid elective labor induction because of a lack of evidence of perinatal benefit and concern about a higher frequency of cesarean delivery and other possible adverse maternal outcomes, particularly among nulliparous women.
Q: Is elective labor induction at 39 weeks in low-risk nulliparous women associated with a higher risk of cesarean delivery than expectant management?
A: In the ARRIVE trial, the percentage of women who underwent cesarean delivery was significantly lower in the induction group than in the expectant-management group (18.6% vs. 22.2%; relative risk, 0.84; 95% CI, 0.76 to 0.93; P<0.001). This finding did not change materially after adjustment for previous pregnancy loss.
A: In the trial by Grobman et al., the authors did not find a significant difference in the frequency of the primary outcome (a composite of adverse perinatal outcomes) between women randomly assigned to labor induction at 39 weeks of gestation and women assigned to expectant management. The primary perinatal outcome occurred in 4.3% of the neonates in the induction group and in 5.4% in the expectant-management group (relative risk, 0.80; 95% CI, 0.64 to 1.00; P=0.049 [P<0.046 indicated statistical significance for the primary perinatal outcome]).
A: Women assigned to induction of labor were significantly less likely than women assigned to expectant management to have hypertensive disorders related to pregnancy (9.1% vs. 14.1%; relative risk, 0.64; 95% CI, 0.56 to 0.74; P<0.001) and to have extensions of the uterine incision during cesarean delivery. Women in the induction group spent more time in the labor and delivery unit, but the length of their postpartum hospital stay was shorter. Neonates in the induction group also had a shorter duration of respiratory support and of total hospital stay.