(1031) Duration of Labor Induction in Nulliparous Women Receiving Magnesium Sulfate and Maternal and Neonatal Outcomes

Friday, February 10, 2023

3:30 PM – 5:00 PM

Objective: We aimed to quantify the effect of magnesium sulfate on duration of labor induction in nulliparous women with hypertensive disorders of pregnancy and maternal and neonatal outcomes.

Study Design: This was a secondary analysis from the Consortium on Safe Labor, a multicenter cohort study of 228,438 deliveries in 19 U.S. hospitals. The analysis included nulliparous women ≥ 18 years old with singleton gestation undergoing induction of labor for hypertensive disorders of pregnancy. Primary outcome was duration of labor induction, defined as time in hours (h) from admission to delivery, between women who received magnesium sulfate and those who did not. Secondary outcomes were rate of cesarean delivery and maternal and neonatal outcomes. Chi-square, t-test, and Mann-Whitney U were used as appropriate to compare groups. This study was IRB exempt #20-000360.

Results: Total 3,026 women met inclusion criteria, of whom 1167 (38.6%) received magnesium sulfate intrapartum. Median duration of labor induction was significantly longer in the magnesium cohort (22.8h, IQR 14.5h–33.1h vs 18.6h, IQR 12.5h-26,1h; p< 0.001). Receipt of magnesium was significantly associated with labor length > 24h (47.1% vs 31.3%, p< 0.001). Magnesium use was significantly associated with higher rates of cesarean delivery (40.2% vs 33.5%, p< 0.001) and placental abruption (1.4% vs 0.1%, p< 0.001), though composite maternal morbidity was not different between groups. Magnesium was associated with higher rates of adverse neonatal outcomes, including higher rates of NICU admission (34.1% vs 12.2%, p< 0.001), 5-minute APGAR ≤ 7 (10.1% vs 4.0%, p< 0.001), respiratory distress syndrome (8.1% vs 2.2%, p< 0.001), and composite neonatal morbidity (37% vs 15%, p< 0.001).

Conclusion: Magnesium sulfate administration is significantly associated with longer duration of labor induction and higher rate of cesarean delivery amongst patients undergoing induction for hypertensive disorders of pregnancy. Appropriate care should be taken in expeditiously managing labor for this high risk patient cohort.

Primary & Presenting Author(s)

Jenny Y. Mei, MD (she/her/hers)
Maternal-Fetal Medicine Fellow
Department of Obstetrics and Gynecology, University of California, Los Angeles
Los Angeles, California, United States

Coauthor(s)

Daniel Lee, MD
OBGYN Resident
UCLA Medical Center
Los Angeles, California, United States
MN
Masaru Negi, MD
Associate Professor
Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles
Los Angeles, California, United States