In the hospital, the women got one of the following two IV treatments: magnesium sulfate, which is used to slow uterine contractions, or a placebo. Their babies were followed for the next two years.
Getting magnesium sulfate to stop preterm birth wasn't linked to any increase in stillbirth or infants dying before their first birthday, and magnesium sulfate was tied to a 45% reduction in the odds that a child would be diagnosed with moderate to severe cerebral palsy by age 2.
Most of the children didn't develop cerebral palsy, but 1.9% of those in the magnesium sulfate group did, compared to 3.5% of those in the placebo group, report the researchers, who included Dwight Rouse, MD, of the University of Alabama at Birmingham.
Adverse events including flushing and sweating were more common among women getting magnesium sulfate treatment, but none of those side effects was life-threatening.
An editorial published with the study calls the findings "promising" but stops short of recommending magnesium sulfate treatment to prevent cerebral palsy when preterm birth is imminent.
"Better understanding is needed of factors that might influence the likelihood that offspring will benefit from maternal magnesium sulfate treatment, such as the reason for imminent preterm birth, the dose of magnesium sulfate, and the timing of administration relative to birth and gestational age," write the editorialists, who included Fiona Stanley, MD, of the University of Western Australia's Centre for Child Health Research.