Antenatal magnesium sulfate treatment and risk of necrotizing enterocolitis in preterm infants born at less than 32 weeks of gestation

Antenatal magnesium sulfate (MgSO₄) treatment is widely used for fetal neuroprotection in women at risk of preterm delivery. However, some studies have recently suggested that in utero MgSO₄ exposure is associated with an increased risk of necrotizing enterocolitis (NEC). This study aimed to investigate the association between antenatal MgSO₄ treatment and risk of NEC. This retrospective cohort study included 756 infants born at 24‒31 weeks’ gestation. Subjects were classified into three groups: period 1, when MgSO₄ treatment protocol for fetal neuroprotection was not adopted (n = 267); period 2, when the protocol was adopted (n = 261); and period 3, when the protocol was withdrawn because of concern of risk of NEC (n = 228). Rates of NEC (≥ stage 2b) were analyzed according to time period and exposure to antenatal MgSO₄. Significant difference in the rate of NEC was not found across the three time periods (2.6% vs. 6.5% vs. 4.8% in periods 1, 2 and 3, respectively, p = 0.103). The rate of NEC was comparable between the infants exposed and unexposed to antenatal MgSO₄ (5.1% vs. 3.6%, p = 0.369). These results showed that antenatal MgSO₄ treatment was not associated with risk of NEC in our study population.