NEW YORK (Reuters Health) - Possible methods of preventing cerebral palsy in full-term and premature infants are suggested by two new studies reported in this week's Journal of the American Medical Association.

Cerebral palsy is a group of chronic disorders that appear in the first few years of life. All of the disorders involve impaired body movement and stem from damage to the brain.

For full-term infants, preventing chorioamnionitis, an infection of the membrane enclosing the fetus, or countering its effects may help prevent cerebral palsy, according to the first report. When a preterm infant is expected, treating the mother with a drug called magnesium sulfate before delivery may reduce the risk of cerebral palsy, the second report suggests.

About half of all cerebral palsy cases involve full- or near-term infants. Although risk factors for cerebral palsy in such infants are unclear, recent reports have suggested an association with chorioamnionitis.

To investigate, Dr. Yvonne W. Wu, from the University of California at San Francisco, and colleagues conducted a study of more than 230,000 infants who were full- or near-term at birth. The study compared the 109 infants identified with cerebral palsy with 218 infants randomly chosen from the study population.

Chorioamnionitis was diagnosed in 14 percent of kids with cerebral palsy, but in only 4 percent of other children. Moreover, on further analysis, this pregnancy problem was a strong predictor of cerebral palsy, associated with a fourfold increased risk. The authors estimate that about 11 percent of cerebral palsy cases were related to chorioamnionitis.

In the second study, Dr. Caroline A. Crowther, from The University of Adelaide in Australia, and colleagues looked at the ability of prenatal magnesium sulfate to reduce the risk of cerebral palsy or death in preterm infants. Previous studies have yielded conflicting results regarding the benefits of such therapy, but, until now, no large trials have tested magnesium sulfate given solely to protect the infant's brain.

The study involved a total of 1062 pregnant women, at risk for preterm delivery, who were treated with intravenous magnesium sulfate or saline before delivery. In all cases, delivery was planned or expected within the next 24 hours.

Infants in the magnesium sulfate group were slightly less likely to die or have cerebral palsy than infants in the control group. However, magnesium sulfate did seem to offer substantial protection against serious movement problems.

"These two important studies as well as other studies provide hope that the risk of cerebral palsy can be reduced among both preterm and term infants," Dr. Jon E. Tyson and Dr. Larry C. Gilstrap, from the University of Texas Medical School in Houston, note in a related editorial.

"Performance of well-designed research to prevent this often devastating condition deserves highest priority," they add.