ARRIVE trial linked to increased elective labor induction for singleton, nulliparous women

Key takeaways:

• Elective labor induction rose by 42% after publication of the ARRIVE trial of induction outcomes.
• No significant change in rates of cesarean birth or hypertensive disorders of pregnancy were observed.

Publication of trial results showing reduced cesarean birth and hypertensive disorders of pregnancy risks with elective labor induction was associated with a rise in elective labor induction for singleton, nulliparous pregnancies.

The ARRIVE trial was a randomized trial of induction vs. expectant management published in August 2018. The trial reported that elective labor induction at 39 weeks gestation for low-risk nulliparous pregnant women resulted in a 16% decrease in cesarean birth risk and a 36% decrease in hypertensive disorders of pregnancy risk compared with expectant management. The trial led to a change in U.S. obstetrics guidelines to indicate that early 39-week inductions were reasonable for first-time, low-risk pregnant women, according to study background.

“Discussions between pregnant women or people and their health care providers about labor should follow principles of shared decision-making. Our study calls into question whether the results from a single randomized control trial are reproducible in other contemporary U.S. birthing populations,” Elizabeth Nethery, RM, PhD, postdoctoral researcher in the Collaboration for Outcomes Research and Evaluation in the department of pharmaceutical sciences at the University of British Columbia, Vancouver, told Healio. “Thirty-nine-week elective inductions of labor may not reduce risks of cesarian delivery for all first-time birthing people or in all populations.”

Nethery and colleagues conducted an interrupted time-series analysis, published in Obstetrics & Gynecology, using clinical data from 28,256 singleton, nulliparous births at 39 weeks gestation or later at 13 hospitals in the Northwest U.S. Overall, 15,208 births occurred before the publication of the ARRIVE trial (January 2016 to July 2018) and 13,048 births occurred after publication (August 2018 to December 2020). Researchers utilized the Obstetrical Care Outcomes Assessment Program to identify elective labor inductions.

The primary outcomes were elective induction, unplanned cesarean births, hypertensive disorders of pregnancy, a composite of perinatal adverse outcomes and NICU admissions.

The rate of elective or medically indicated labor induction was 34.7% before publication of the ARRIVE trial and 43% after publication. Before the ARRIVE trial, the rate of elective labor induction was 3.6% and 10.8% after the trial was published. Immediately after the publication, researchers noted an increase of 42% in elective labor induction (RR = 1.42; 95% CI, 1.18-1.71).

Researchers observed no statistically significant change in rates of cesarean birth (pre-ARRIVE, 27% vs. post-ARRIVE, 25.9%; RR = 0.96; 95% CI, 0.89-1.04) or hypertensive disorders of pregnancy (pre-ARRIVE, 8.3% vs. post-ARRIVE, 9.7%; RR = 0.91; 95% CI, 0.79-1.06). In addition, there was no immediate change in adverse perinatal outcomes after the ARRIVE trial was published. However, there was a 3% statistically significant increase in the trend of adverse perinatal events over time (RR = 1.03; 95% CI, 1.01-1.05) vs. a declining trend prior to the publication (RR = 0.98; 95% CI, 0.96-0.99).

“A larger sample might be able to detect small changes in outcomes, which we could not,” Nethery said. “The Obstetrical Care Outcomes Assessment Program is one of several programs of the Foundation for Health Care Quality, a nonprofit, neutral organization focused on health system-wide improvement and patient safety.”