Timing of oxytocin infusion following extra-amniotic balloon cervical ripening and delivery outcomes.

OBJECTIVE

Mechanical methods for cervical ripening, such as extra-amniotic balloons (EABs), are effective in promoting labor onset. We aimed to determine the association between the time interval from Foley catheter balloon expulsion to subsequent oxytocin induction and adverse delivery outcomes.

METHODS

This was a retrospective cohort of 1261 patients who had undergone cervical ripening with EAB followed by medical induction of labor by oxytocin infusion. The time interval between EAB expulsion and oxytocin initiation was calculated, and the cohort was divided into groups above (n = 127) and below (n = 1134) the 90th percentile for the study population. The primary outcome was operative delivery (vacuum-assisted or cesarean deliveries), and the secondary outcomes were maternal and neonatal complications.

RESULTS

The 90th percentile time interval was 24.7 h. Patients with time intervals at or above this threshold had a higher rate of operative delivery than women with shorter time intervals (45.7% vs. 32.7%, P = 0.004). This was secondary to an increase in the rate of vacuum-assisted deliveries, with no significant difference in the rate of cesarean sections. The association was confirmed after adjustment for confounding variables (maternal age, body mass index, parity, diabetes, and neonatal birth weight) by multivariate regression analysis (adjusted odds ratio, 1.65 [95% confidence interval, 1.05-2.62]; P = 0.03). Other outcomes were similar for both groups.

CONCLUSION

Delayed initiation of oxytocin following cervical ripening with EAB is associated with higher rates of operative deliveries.