Two new studies are offering mixed signals about the long-term safety of repeatedly giving pregnant women steroid drugs intended to prevent complications once a premature delivery seems likely.
While one report in the New England Journal of Medicine found little evidence that the widespread practice is dangerous, another study in the medical magazine offers hints that repeated injections may raise the risk of cerebral palsy in babies born to the women receiving steroids.
Doctors give such drugs to help the fetus' lungs mature quickly if they suspect premature delivery. But the baby does not always come as soon as expected, raising the question of whether steroid treatment should continue in that situation. Currently doctors often continue to administer steroid injections, sometimes weekly.
There has been little evidence, until now, to show if the strategy is safe. Animal tests have suggested that brain development and body size might be affected.
The studies found that the mothers who received extra injections of the steroid betamethasone delivered babies that were not any different from normal in their body size measurements and had no significant differences in blood pressure or development at age 2 or 3.
The first study, led by Caroline Crowther of the University of Adelaide in Australia, found that 84 percent of the 521 fetuses exposed to more than one steroid treatment were free of a major disability at the age of 2.
This compared to 81 percent of the 526 children from mothers who had been given placebo shots after the first steroid injection.
"The only significant difference between groups was in attention problems, which were slightly more common in children in the repeat-corticosteroid group, but the difference was small," Alan Stiles of the University of North Carolina at Chapel Hill wrote in a commentary.
The second study, which looked at children age 2 to 3, found that infant development scores were the same for 235 children who has been exposed to betamethasone and 230 whose mothers had been given placebo shots.
However the team, led by Ronald Wapner of Columbia University in New York, found that 2.9 percent of the steroid-treated pregnancies produced a baby with cerebral palsy, compared to a rate of 0.5 percent among the children of placebo recipients.
The difference may have been a fluke because there were not enough cases to tell if it was statistically significant.
Yet Wapner and his colleagues urged caution and said the cerebral palsy question should be studied further.