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Q&A

Clinical Obstetrics

Poster Session 3

(868) Impact of the ARRIVE Trial in Nulliparous Individuals with Morbid Obesity: Interrupted Time Series Analysis

Wednesday, February 14, 2024
8:30 AM – 10:00 AM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective:

Since the ARRIVE trial (A Randomized Trial of Induction Versus Expectant Management) was published in 2018, the number of induction of labor (IOL) in nulliparas has increased. Given that the median body mass index (BMI) in the ARRIVE trial was 30.5 kg/m2, the generalizability of the benefits of elective induction to patients with morbid obesity (BMI≥40kg/m2) is not clear. We aimed to examine rates of induction of labor (IOL) and cesarean delivery (CD) before and after the ARRIVE trial stratified by BMI category at the population level.

Study Design:

This was a repeated cross-sectional analysis of publicly available US birth certificate data from 2015 to 2021. We limited analyses to nulliparas with singleton pregnancy without chronic hypertension and diabetes (gestational or pregestational) who delivered between 39 and 42weeks’ gestation. The dissemination period of the ARRIVE trial was from Feb 2018 to Dec 2018. The pre-ARRIVE period was from Aug 2015 to Jan 2018. The Post-ARRIVE trial period was from Jan  2019, to June 2021. We conducted an interrupted time series analysis after stratifying by BMI (< 40 or ≥40). Poisson regression to calculate adjusted incident rate ratios (aIRR) with 95% confidence intervals (95%CI).

Results:

Of 2,666,235 individuals 2,578,484(96.7%) had BMI< 40 and 87,751(3.3%) had BMI ≥40. In nulliparas with BMI< 40, the post-ARRIVE period compared to the pre-ARRIVE period was associated with increased rates of IOL (37.0% observed vs. 35.0% expected; aIRR, 1.06; 95%CI 1.05-1.08) and decreased rates of CD (24.4% observed vs. 24.7% expected; aIRR, 0.97; 95%CI, 0.96-0.99).  On the other hand, in nulliparas with BMI≥40, there was a significant increase in IOL (52.8% observed vs. 50.2% expected; aIRR, 1.06 95%CI, 1.01-1.11); however, the decrease in CD was not significant (44.7% observed vs. 46% expected; aIRR, 0.97; 95%CI, 0.92-1.02).

Conclusion:

The dissemination of the ARRIVE trial had the expected impact on IOL rates in nulliparas with and without morbid obesity. Only nulliparas without morbid obesity benefited from decreased CD rates.