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CME Credit Offered
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Poster Session 4

(1051) Maximum oxytocin dose in labor induction and associated pregnancy outcomes in nulliparous individuals

Friday, January 31, 2025
4:00 PM – 6:00 PM  
Objective: Oxytocin is often used for induction of labor (IOL) with a lack of evidence-based guidelines on its maximum dose. In some institutions, 20 milliunits/minute (mU/min) is used as a maximum dose due to concerns about adverse outcomes at higher rates. We sought to evaluate the relationship between the maximum dose of oxytocin with maternal and neonatal outcomes in low-risk nulliparous individuals.

Study Design: This secondary analysis of the MFMU ARRIVE trial included nulliparous individuals who underwent IOL. The primary exposure was maximum oxytocin dose categorized as ≤ 20 or > 20 mU/min. Logistic regression was used to adjust for gestational age, body mass index, induction without medical indication, Bishop score on admission, and hypertensive disorders of pregnancy.

Results: Of the 3,565 participants included in this secondary analysis, 2,673 (75%) were exposed to a maximum dose of oxytocin of ≤ 20 mU/min and 892 (25%) were exposed to a maximum dose of > 20 mU/min. Those who were exposed to > 20 mU/min of oxytocin had a greater median BMI (p< 0.001) and a lower Bishop score on admission (p< 0.001)(Table 1). Duration from initiation of oxytocin to delivery was longer in the higher-dose group compared to the lower-dose group (median[IQR] ≤ 20 mU/min: 12.1[8.2-17] vs. > 20 mU/min: 21.2 [15.9-257] hours; p< 0.001). Individuals exposed to < 20 mU/min of oxytocin had higher rates of cesarean delivery (adjusted odds ratio [aOR] 1.23, 85%CI 1.01-1.48), cesarean deliver for labor dystocia (aOR 1.63, 95%CI 1.28-2.07), and postpartum hemorrhage (aOR 1.51, 95%CI 1.09-2.09)(Table 2). There was no difference in rates of cesarean delivery for non-reassuring fetal status (aOR 0.80, 95%CI 0.62-1.03), NICU admissions (aOR 1.03 95%CI 0.82-1.30), or neonatal adverse outcomes (aOR 0.97, 95%CI 0.68-1.39).

Conclusion: This analysis showed no difference in rates of cesarean delivery for non-reassuring fetal status or adverse neonatal outcomes at oxytocin rates > 20 mU/min, suggesting that 20 mU/min should not be used as a maximum dose during IOL of nulliparous individuals.