Changes in obstetric practice in low-risk nulliparous women following publication of the ARRIVE trial

Abstract

The ARRIVE trial demonstrated the potential benefit of elective labor induction at 39 weeks. Our objective was to determine if there were changes in labor induction, timing of delivery, and mode of delivery among low-risk nulliparous women after the ARRIVE trial publication. This was a retrospective cohort study of nulliparous women who started prenatal care by 12 weeks with singleton, non-anomalous deliveries at ³ 39 weeks in the US. Data were extracted from the US Natality database. The study group consisted of women delivered in 2019, and the control group consisted of women delivered between Jan 2015 to Dec 2017. We excluded births that occurred in the year of the ARRIVE trial publication. Univariate and multivariate analyses were performed to compare rate of inductions, delivery timing, and cesarean delivery. Trends were also tested across time periods. There were 609,322 patients in the study group and 1,966,870 in the control group. The study group differed in age, body mass index, marital status, infertility, and smoking history (p< 0.001). After adjusting for these differences, the study group was more likely to undergo induction (36.1% v. 30.2%, p< 0.001) and deliver at 39 weeks (42.8% v. 39.9%, p< 0.001). The study group had a significantly lower rate of cesarean delivery than the control group (27.3 % v. 27.9%, p< 0.001); there were no significant trends in the yearly cesarean rate between 2015 and 2017 (p=0.451). After the ARRIVE trial publication, there were more labor inductions, deliveries at 39 weeks, and a small, but statistically significant, reduction in cesarean deliveries among low-risk nulliparous women in the US. Further research is warranted in regards to the impact of the ARRIVE trial results and other potential motivators for these practice changes within individual departments.