Magnesium sulfate infusions reduce cerebral palsy risk in preterm births

January 31, 2008 — Giving an infusion of magnesium sulfate just before delivery to pregnant women who were at high risk for preterm birth cut the rate of cerebral palsy in the children born by half, a new study found.

“This is one of the most promising breakthroughs in the management of high-risk pregnancies in more than 30 years,” said Dr. John Thorp, a study co-author and McAllister distinguished professor of obstetrics and gynecology at the University of North Carolina at Chapel Hill.

“The active ingredient we used in this study, magnesium sulfate, is better known as Epsom salt,” Thorp said. “And virtually every delivery room in the United States is already stocked with magnesium sulfate solutions that are given to pregnant women during childbirth for other reasons.

“So what we have learned from this study is that we have a cheap, widely available treatment already in hand that cuts in half the risk of babies being born with an extremely disabling disorder. That is a tremendously exciting development,” Thorp said.

Results of the study will be presented Thursday (Jan. 31, 2008), at the annual meeting of the Society for Maternal-Fetal Medicine in Dallas. The lead author is Dr. Dwight J. Rouse of the University of Alabama at Birmingham. The study was conducted for the Maternal-Fetal Medicine Units Network of the National Institute of Child Health and Human Development, which provided grant funding. It took place at 20 sites across the United States, including UNC Hospitals.

In the study, 2,241 women who had been diagnosed at high risk for giving birth prematurely, between 24 and 31 weeks into their pregnancies, were randomized to receive an intravenous infusion of magnesium sulfate solution or an identically appearing placebo. The infusions were begun when delivery seemed imminent, at a rate of 6 grams infused over 20-30 minutes followed by a maintenance infusion of 2 grams per hour. If delivery did not occur within 12 hours, the infusion was stopped and resumed later when delivery once again appeared at hand.

The researchers were looking to see if magnesium sulfate reduced the rate of stillbirth or infant death, or reduced the rate of moderate or severe cerebral palsy at or beyond the age of 2 years. They found that the risk of death did not differ significantly between the magnesium sulfate and placebo groups. However, moderate or severe cerebral palsy occurred about half as often in the magnesium sulfate group than in the placebo group, 1.9 percent versus 3.5 percent.
An earlier study conducted in Australia, which included more than 3,000 women, reached similar results. Viewing both studies together, the researchers in the U.S. study concluded that the use of magnesium sulfate to prevent cerebral palsy in the children of women at imminent risk of early preterm delivery “should be strongly considered.”

Doctors who specialize in managing the pregnancies of women at high risk for preterm birth could begin using the magnesium sulfate treatment immediately, if they choose to do so, Thorp said. Approval for the treatment from the Food and Drug Administration is not required. In addition, the U.S. and Australian studies are the largest, most rigorously conducted and pertinent trials to date and are not likely to be replicated, Thorp said.

Society for Maternal-Fetal Medicine Web site:

Note: Thorp can be reached at (919) 843-7851 or

School of Medicine contact: Stephanie Crayton, (919) 966-2860 or

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School of Medicine contact: Stephanie Crayton, (919) 966-2860 or
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