In a recent study, temporal trends indicated a rise in induction at 39 weeks of gestation and decrease in cesarean delivery among low-risk nulliparous patients in the United States.
According to a recent study published in JAMA Network Open, rates of induction at 39 weeks of gestation increased among low-risk nulliparous patients in the United States while cesarean deliver (CD) rates decreased following the publication of the A Randomized Trial of Induction vs Expectant Management (ARRIVE) trial.
The ARRIVE trial, published in the New England Journal of Medicine in 2018, found a 16% relative risk reduction in CD compared to expectant management among low-risk, nulliparous patients with induction at 39 weeks of gestation. To determine if this trial was associated with changes in obstetric practices in the United States, investigators conducted a cross-sectional study.
Participants included low-risk nulliparous patients who delivered at a gestational period of at least 39 weeks from January 2016 to March 2020. These individuals underwent a population-level interrupted time series (ITS) analysis. Low risk was determined by, “a singleton, vertex-presenting, nonanomalous live birth without chronic hypertension or diabetes.”
The period of January 2016 to July 2018 was reported as the pre-ARRIVE period. The publication of the ARRIVE trial was in August 2018, which was followed by a dissemination period lasting for 3 months. November 2018 to March 2020 was chosen as the post-ARRIVE period, with the ending date chosen to avoid cofounding from the COVID-19 pandemic.
Rates of 39-week induction and CD among low-risk nulliparous patients from week 39 of gestation onward were reported as the primary outcome of the study. Poisson regression was used to design the primary ITS model. Investigators also controlled for the rate of patients aged 35 years or older with a body mass index (BMI) of 30 or more. Demographic information was also collected.
There were 2,860,942 livebirths included in the final analysis, 66% of which occurred in the pre-ARRIVE period and 34% in the post-ARRIVE period. Of patients in the pre-ARRIVE period, 7.7% were aged 35 years and older, 19.9% had a BMI of 30 or higher, 75.1% were White, and 21.8% were Hispanic. In post-ARRIVE patients, these rates were 8.4%, 21.5%, 75%, and 23% respectively.
Following the dissemination period, an immediate increase in the rate of induction at 39 weeks was observed. The expected rate was 13.8% based on pre-ARRIVE trends, while the reported rate was 15%. An increase of 0.009 39-week inductions and decrease of 0.0014 CDs per months were also observed over time.
These results indicated an increase in 39-week inductions and decrease of CDs following the publication of the ARRIVE trial. Investigators recommended further studies to determine if these trends are found in different subgroups.
Wood R, Freret T, Clapp M, Little S. Rates of induction of labor at 39 weeks and cesarean delivery following publication of the ARRIVE trial. JAMA Netw Open. 2023;6(8):e2328274. doi:10.1001/jamanetworkopen.2023.28274