• D J Rouse, J C Hauth, K G Nelson, and R L Goldenberg.
• Department of Obstetrics and Gynecology, University of Alabama at Birmingham, USA.
• Am. J. Obstet. Gynecol. 1996 Sep 1; 175 (3 Pt 1): 701-5.

ObjectiveBecause recent epidemiologic data suggest an association between maternal magnesium sulfate use and a decreased risk of cerebral palsy in infants who survive preterm birth, we investigated the feasibility of a randomized trial of intrapartum maternally administered magnesium sulfate to prevent cerebral palsy in children who were born before term.Study DesignOn the basis of a literature review, we calculated cumulative rates of delivery, neonatal survival, and cerebral palsy for progressively longer gestational age intervals beginning at 24 weeks' gestation. Sample size estimates with two-tailed chi 2 tests without Yates' correction (alpha = 0.05, beta = 0.2, 50% effect size) for a clinical trial were calculated for these rates.ResultsIn the 4-week interval from 24 weeks 0 days to 27 weeks 6 days the minimum number of neonates required to conduct a randomized trial would be 1189. Loss to follow-up of neonates, maternal ineligibility, and failure of enrollment would substantially increase the number of necessary gravid women delivered in the 4-week interval to complete such a trial, such that 1 million pregnancies would be required to generate the necessary number of eligible gravid women. Shorter gestational age intervals (e.g., 24 weeks 0 days to 25 weeks 6 days) required fewer neonates (n = 729) but more pregnancies (n = 1.5 million). Because of the decreasing prevalence of cerebral palsy at higher gestational ages, extending the gestational age interval (e.g., to 29 weeks 6 days) markedly increased the minimum number of neonates to 1982 but only slightly decreased the necessary number of pregnancies, to 900,000.ConclusionsA randomized trial of maternally administered intrapartum magnesium sulfate to reduce the rate of cerebral palsy in surviving preterm neonates would be a formidable undertaking, requiring a concerted multicentered effort.

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