Magnesium sulfate for women at risk of preterm birth does not reduce cerebral palsy risk

For pregnant women at risk of delivering preterm, intravenous administration of magnesium sulfate prior to preterm birth at 30–34 week of gestation does not appear to minimize the chances of child survival free of cerebral palsy at 2 years, as shown in a study.

The study included 1,433 pregnant women (mean age 30.6 years, 67.4 percent White) expected to deliver at 30 to 34 weeks of gestation and their 1,679 infants. These women were randomly assigned to receive an intravenous infusion of magnesium sulfate 4 mg or placebo between 30 and 34 weeks of gestation.

The analysis included 1,365 (81 percent) offspring: 691 in the magnesium group and 674 in the placebo group. The primary outcome of death or cerebral palsy at 2 years’ corrected age did not differ significantly between the magnesium and placebo groups (3.3 percent vs 2.7 percent; adjusted relative risk [RR], 1.19, 95 percent confidence interval [CI], 0.65–2.18). Likewise, the incidence of individual components of the primary outcome did not differ between the two groups.

However, neonates in the magnesium group were not as prone to having respiratory distress syndrome (34 percent vs 41 percent; adjusted RR, 0.85, 95 percent CI, 0.76–0.95) and chronic lung disease (5.6 percent vs 8.2 percent; adjusted RR, 0.69, 95 percent CI, 0.48–0.99) during the birth hospitalization as those in the placebo group.

None of the participants had serious adverse events (AEs), but AEs occurred more frequently among pregnant women who received magnesium vs placebo (77 percent vs 20 percent; adjusted RR, 3.76, 95 percent CI, 3.22–4.39).

Compared with those in the placebo group, pregnant women in the magnesium group were less likely to have a caesarean delivery (56 percent vs 61 percent; adjusted RR, 0.91, 95 percent CI, 0.84–0.99), although more women in the magnesium group had a major postpartum haemorrhage (3.4 percent vs 1.7 percent; adjusted RR, 1.98, 95 percent CI, 1.01–3.91).

Researchers advised caution when interpreting these results due to the study having limited power to detect small between-group differences.