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Inflammation of placental membranes may be risk factor for cerebral palsy

The JAMA Network Journals

In an article in the November 26 JAMA, researchers found that chorioamnionitis, or inflammation of the placental membranes, is associated with a four-fold increased risk of cerebral palsy among term and near term infants.

According to background information in the article, cerebral palsy (CP), a group of nonprogressive motor impairment syndromes caused by lesions of the brain arising early in development, occurs in 1 to 2.4 per 1000 live births. Half of all cases of CP occur in term infants, for whom risk factors have not been clearly defined. Recent studies have suggested a possible role of chorioamnionitis. The researchers in this study examined whether clinical chorioamnionitis increases the risk of CP in term and near-term infants.

The study, conducted by Yvonne W. Wu, M.D., M.P.H., of the University of California, San Francisco, and colleagues, included data from 327 infants (including 109 with moderate to severe CP and 218 control infants) born at 36 or more weeks' gestation between January 1, 1991, and December 31, 1998, in the Kaiser Permanente Medical Care Program. This managed care organization providing care for more than 3 million residents of northern California. Case patients were identified from electronic records and confirmed by chart review by a child neurologist, and comprised all children with moderate to severe spastic or impairment of movement CP not due to brain injury occurring after birth or developmental abnormalities. Controls were randomly selected from the study population.

The researchers found that most CP cases had some paralysis; 87 percent had been diagnosed by a neurologist and 83 percent had undergone neuroimaging. Chorioamnionitis, considered present if a treating physician made a diagnosis of chorioamnionitis or endometritis clinically, was noted in 14 percent of cases and 4 percent of controls. Independent risk factors for CP included chorioamnionitis (4.1 times increased risk); intrauterine growth restriction (four times increased risk); maternal black ethnicity (3.6 times increased risk); maternal age older than 25 years (2.6 times increased risk); and first birth by the mother (1.8 times increased risk).

"We conclude that chorioamnionitis confers a 4-fold overall increased risk of CP in term infants," the researchers write. (JAMA. 2003;290:2677-2684. Available post-embargo at JAMA.com)

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Editor's Note: This study was funded by the United Cerebral Palsy Foundation. Dr. Wu is a recipient of the Neurological Sciences Academic Development Award grant.

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