Objective: We aimed to assess the impact of antenatal MgSO4 therapy given to women with PPROM before 32 weeks’ gestation on latency, maternal outcomes, perinatal outcomes, and neurodevelopmental outcomes.Methods: We undertook a retrospective cohort observational study of 184 singleton pregnancies complicated by PPROM at 23°–316 weeks who were hospitalized and received magnesium therapy for tocolysis (MgSO4 group) or did not receive tocolytic therapy (no MgSO4 group) between 2005 and 2013. Furthermore, patients were subdivided into two groups based on the gestational age at the onset of PPROM (23°–276 weeks’ gestation and 28°–316 weeks’ gestation).Results: We included 184 women, of whom 143 received magnesium therapy and 41 did not. The latency period was significantly longer in the MgSO4 group compared with no MgSO4 group (7.9 ± 9.0 versus 4.0 ± 6.0 days, p = .0017). Antenatal magnesium therapy was significantly associated with decreased stillbirth (1.4% versus 14.6%, p = .0012) and perinatal mortality (7% versus 19.5%, p = .0375) without significant increase in the risk of neonatal morbidities and chorioamnionitis. However, neonates who were exposed to antenatal MgSO4 were associated with higher Mg levels (3.63 ± 1.05 mg/dl versus 2.13 ± 0.48 mg/dl, p < .0001) and phosphate levels (6.90 ± 1.36 mg/d versus 6.40 ± 1.01 mg/dl, p = .0459) than those who were not exposed. Neonates who were exposed to MgSO4 showed significantly reduced risks of IVH (20.4% versus 58.3%; RR, 0.35; 95%CI, 0.17–0.71) and PVL (27.8% versus 58.3%; RR, 0.48; 95%CI, 0.25–0.91) in the subgroup of 23°–276 weeks’ gestation. And the incidence of developmental delay in the subgroup of 23°–276 weeks’ gestation was significantly lower in the MgSO4 group (6.5% versus 36.4%; RR, 0.18; 95%CI, 0.05–0.69). However, there were no significant differences in the development of IVH, PVL, and developmental delay between the two groups for patients in the subgroup of 28°–316 weeks’ gestation. A similar trend was observed for cerebral palsy, with 22.2% of unexposed children affected compared with only 7.0% of exposed children (RR, 0.31; 95%CI, 0.10–1.00).Conclusions: Antenatal magnesium therapy in women with PPROM before 32 weeks’ gestation could prolong latency period, allowing for corticosteroid benefit. Moreover, MgSO4 showed fetal neuroprotective effects for neonatal IVH and PVL, and for developmental delay in infancy while prolonging latency. However, these benefits were primarily limited to the subgroup of 23°–276 weeks’ gestation and prolonged in utero exposure to MgSO4 was associated with bone mineralization in the neonates.
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