(332) Maternal and Neonatal Outcomes by Cervical Status: A Secondary Analysis of the ARRIVE Trial

Objective:
The ARRIVE trial found that low-risk nulliparous women induced electively at term had lower cesarean delivery and preeclampsia rates, but no difference in neonatal outcomes, compared to expectant management. Our objective was to assess the overall impact of induction on both maternal and neonatal outcomes, as well as how cervical status modifies this effect.

Study Design:
This was a secondary analysis of the ARRIVE trial. We used multivariable multinomial regression to assess the association between labor induction and a three-level categorical delivery outcome: uncomplicated vaginal delivery, uncomplicated cesarean section, or a composite of complicated vaginal or cesarean delivery. This composite complication outcome included, but was not limited to, maternal death, postpartum hemorrhage, uterine rupture, ICU admission, venous thromboembolism, and neonatal outcomes such as stillbirth, 5-minute Apgar score less than 7, hypoxic-ischemic encephalopathy, seizure, birth trauma, or mechanical ventilation. The analysis was stratified by Bishop score at randomization (0-2, 3-4, 5-6, and ≥7). Models were adjusted for maternal age, body mass index, race, ethnicity, and lifestyle factors.

Results:
Among 5,968 participants, 3005 pregnancies were induced and 2963 were managed expectantly. Among women with a Bishop score of 0-2, labor induction was associated with a significantly lower rate of uncomplicated cesarean delivery compared to expectant management (18.7% vs. 23.0%, p=0.034). For those with a Bishop score of 3-4, induction was associated with a lower rate of the composite outcome of complicated vaginal or cesarean delivery (13.8% vs. 17.5%, p=0.020). Across all Bishop score categories, labor induction was consistently associated with an approximately 3% absolute increase in the rate of uncomplicated vaginal delivery (Figure 1).

Conclusion:
In low-risk nulliparous women, labor induction at 39 weeks is associated with more favorable maternal and neonatal outcomes across multiple Bishop score categories. These findings support the benefits of induction regardless of cervical status.