J Matern Fetal Neonatal Med. 2026 Dec;39(1):2613553. doi: 10.1080/14767058.2026.2613553. Epub 2026 Jan 11.
ABSTRACT
OBJECTIVE: Magnesium sulfate is administered intrapartum for seizure prophylaxis in patients with preeclampsia with severe features. We aimed to quantify the effect of magnesium sulfate on duration of labor induction in nulliparous patients undergoing induction of labor for hypertensive disorders of pregnancy at term gestation.
METHODS: This retrospective cohort study 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 patients ≥ 18 years old with singleton gestation undergoing induction of labor for hypertensive disorders of pregnancy with delivery at ≥37 weeks gestation. Primary outcome was duration of labor induction, defined as time in hours (h) from initiation of induction to delivery, between patients who received magnesium sulfate and those who did not. Secondary outcomes were rate of cesarean delivery and perinatal outcomes.
RESULTS: Total 5,886 patients met inclusion criteria, of whom 2102 (35.7%) received magnesium sulfate intrapartum. Median duration of labor induction was significantly longer in the magnesium cohort (16.8h, IQR 10.3h-25.3h vs 15.0h, IQR 9.0h-22,9h; p < 0.001). Multivariate logistic regression controlling for baseline characteristics different between groups found that magnesium use was significantly associated with labor length over 12 h (adjusted odds ratio [aOR] 1.36; 95% confidence interval [CI] 1.21-1.54; p < 0.001) as well as over 24 h (aOR, 1.44; 95% CI, 1.26-1.64; p < 0.001). The overall rate of CD was 39.2% in the cohort. Magnesium use was not associated with higher rate of CD (p = 0.58) but was associated with longer maternal length of stay (p < 0.001) and higher rate of endometritis (p < 0.001). Magnesium use was associated with higher rates of neonatal intensive care unit admission (p < 0.001), 5-minute APGAR ≤ 7 (p < 0.001), respiratory distress syndrome (p < 0.001), and composite neonatal morbidity (p < 0.001).
CONCLUSION: Magnesium sulfate administration is significantly associated with longer induction of labor length amongst patients undergoing induction for hypertension, though it did not impact mode of delivery. Appropriate care should be taken in expeditiously managing labor for this high-risk patient cohort.
PMID:41521063 | DOI:10.1080/14767058.2026.2613553