Corticosteroids reduce inflammation in the body. They are different from steroids used to increase muscle mass.
Corticosteroids may be given to pregnant women who are likely to give birth early. The corticosteroids spur the baby's lung development, giving the baby a better chance of surviving preterm birth.
The studies, published along with an editorial in The New England Journal of Medicine, don't settle the issue one way or the other.
Until long-term results become available ,"it may be prudent to consider the use of lower doses" of corticosteroids for pregnant women, states the editorial.
The two new studies included pregnant women at high risk of preterm labor who got one corticosteroid shot or repeated corticosteroid shots.
The babies born from those pregnancies were followed until age 2.
One study included 556 babies. In general, the researchers saw no physical or brain-related differences between the babies whose moms had gotten one corticosteroid shot or repeated corticosteroid shots during pregnancy.
But there was a possible exception. Six babies whose mothers had gotten repeated corticosteroid shots -- nearly 3% -- developed cerebral palsy by age 2, compared with one baby (less than 1%) whose mother had gotten only one corticosteroid shot during pregnancy.
Those findings are "of concern" and "warrant further study," write the researchers, who included Ronald Wapner, MD, of Columbia University.
But Wapner's team isn't saying that corticosteroids make cerebral palsy more likely, since the study's cerebral palsy statistics may have been due to chance.
The second study showed no uptick in cerebral palsy among 1,047 babies whose mothers received corticosteroids during pregnancy.
In fact, the results show that repeated doses of corticosteroids cut newborns' health risks without affecting the children's brain-related disability risk or body size in the first two years of life.
The researchers who worked on that study included Caroline Crowther, MD, of Australia's University of Adelaide.
Low Doses Best?
How to square the results of those studies? Do more research, suggests editorialist Alan Stiles, MD, of the pediatrics department at the University of North Carolina at Chapel Hill.
"More information is needed before it will be clear which strategy is optimal," Stiles writes.
The two studies used different corticosteroid doses. The lower dose may be the safer choice pending further research, Stiles suggests.
"In all cases," Stiles writes, "we should inform parents of the limited data on long-term outcomes and should follow survivors for long-term neurodevelopmental outcomes."