Study: Magnesium sulfate cuts risk of CP in preemies

Giving a cheap and widely available drug to pregnant women at high risk of premature delivery cut the risk of cerebral palsy in their babies by nearly half, according to a study presented Thursday.

Premature babies are at high risk for cerebral palsy, an often devastating movement disorder caused by brain damage before, during or after birth, says study co-author John Thorp, a professor at the University of North Carolina at Chapel Hill. About one-third of cerebral palsy cases are caused by early preterm birth, he says.

Giving magnesium sulfate, or Epsom salt, could save many children from the condition, Thorp says. Doctors regularly use the drug to halt contractions when women go into labor very early. The drug is found in virtually every labor and delivery department and costs just pennies a dose, he says.

In Thorp's study, presented at the Society for Maternal-Fetal Medicine annual meeting in Dallas, doctors focused on 2,241 women whose water broke very early — between the 24th and 31st weeks of pregnancy. A full-term delivery occurs after at least 37 weeks.

Doctors randomly assigned some women to get intravenous magnesium sulfate and others to get a placebo, a study design that's considered the "gold standard" of medical testing.

About 1.9% of women on magnesium sulfate had babies with moderate or severe cerebral palsy, compared to 3.5% of women who didn't get the drug, the study shows. The drug caused no serious side effects, although more women taking magnesium sulfate felt flushed or sweaty. Some reported temporarily blurred vision.

"This is a real breakthrough," says Thorp, noting that his study is especially powerful because it confirms the findings of a 2003 Australian study. "These are children who have their whole lives in front of them."

About 2 or 3 children in 1,000 over the age of 3 are diagnosed with cerebral palsy every year, says Dara Richardson-Heron, national medical director of United Cerebral Palsy, which wasn't involved in the study. She called the study "very promising."

Margarita de Veciana, a maternal-fetal medicine specialist at Eastern Virginia Medical School in Norfolk, Va., says Thorp's study is likely to spark a debate.

Some doctors are now using drugs other than magnesium sulfate to prevent preterm labor, de Veciana says, because studies haven't shown that magnesium sulfate works as well as previously believed. Doctors may reconsider abandoning magnesium sulfate, however, if it can prevent disabilities.

"This could have a huge impact," de Veciana says.

Geeta Swamy, a maternal-fetal medicine specialist and assistant professor at Duke University Medical Center, says Thorp's study isn't likely to change the way women are treated right away.

Although the drug caused no serious problems in Thorp's study, Swamy says a handful of women each year do have bad reactions to magnesium sulfate, which can sometimes cause respiratory problems. Doctors will want to scrutinize Thorp's data to decide if the drug's benefits outweigh its risks.

"This study has the potential to change practice, but we don't have enough information yet," Swamy says.