Data from retrospective observational studies suggest that fetal exposure to magnesium sulfate may correlate with a lower risk of both intraventricular hemorrhage and cerebral palsy in live-born infants. The present study, also retrospective, was done to learn whether extremely low birth weight (1000 gm or less) infants who live at least 2 days after being born to a woman given magnesium for uterine tocolysis had neonatal outcomes differing from those of unexposed infants. Only potentially viable singleton infants with a gestational age of at least 20 weeks were included. None had major congenital anomalies. The final study group of 308 infants, seen in a 12-month period, included 124 exposed in utero to magnesium sulfate and 184 who were not so exposed.
Mortality from day 3 to 4 months of life was similar in the two groups. Women given magnesium sulfate for tocolysis were less often black, were more often in active labor at the time of delivery, and received more steroids, but in other respects, the groups were comparable. The infants were similar in birth weight and gestational age at delivery, and there were no significant differences in neonatal morbidity. Multivariate analysis affirmed the lack of any significant association between neonatal disorders and exposure to magnesium sulfate. This included measures of neurological morbidity such as seizure activity and intraventricular bleeding. A prospective randomized trial is needed before concluding that intrapartum magnesium sulfate does not improve the neurological outcome in very premature infants.
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Alabama at Birmingham; The NICHD Network of Maternal-Fetal Medicine Units, Rockville, Maryland
Am J Perinatol 1998;15:635-641