Chorioamnionitis and cerebral palsy in term and near-term infants

Context Half of all cases of cerebral palsy (CP) occur in term infants, for whom risk factors have not been clearly defined. Recent studies suggest a possible role of chorioamnionitis. Objective To determine whether clinical chorioamnionitis increases the risk of CP in term and near-term infants. Design, Setting, and Patients Case-control study nested within a cohort of 231582 singleton infants born at 36 or more weeks' gestation between January 1, 1991, and December 31,1998, in the Kaiser Permanente Medical Care Program, a 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. dyskinetic CP not due to postnatal brain injury or developmental abnormalities (n=109). Controls (n=218) were randomly selected from the study population. Main Outcome Measure Association between clinical chorioamnionitis and increased risk of CP in term and near-term infants. Results Most CP cases had hemiparesis (40%) or quadriparesis (38%); 87% had been diagnosed by a neurologist and 83% had undergone neuroimaging. Chorioamnionitis, considered present if a treating physician made a diagnosis of chorioamnionitis or endometritis clinically, was noted in 14% of cases and 4% of controls (odds ratio [OR], 3.8; 95% confidence interval [CI], 1.5-10.1; P=.001). Independent risk factors identified in multiple logistic regression included chorioamnionitis (OR, 4.1; 95% CI, 1.6-10.1), intrauterine growth restriction (OR, 4.0;95% CI, 1.3-12.0), maternal black ethnicity (OR, 3.6; 95% CI, 1.4-9.3), maternal age older than 25 years (OR, 2.6; 95% CI, 1.3-5.2), and nulliparity (OR, 1.8; 95% CI, 1.0-3.0). The population-attributable fraction of chorioamnionitis for CP is 11%. Conclusion Our data suggest that chorioamnionitis is an independent risk factor for CP among term and near-term infants.