Maternal autoimmune diseases, asthma and allergies, and childhood autism spectrum disorders: a case-control study

This is a case-control study nested within a cohort of infants born between January 1995 and June 1999. SETTING: Northern California Kaiser Permanente Medical Care Program. PARTICIPANTS: Cases (n = 420) were children with at least 1 diagnosis of an autism spectrum disorder (ASD) recorded in Kaiser Permanente outpatient clinical databases. Controls (n = 2100) were children without an ASD diagnosis who were frequency matched to cases on sex, birth year, and hospital of birth. MAIN OUTCOME MEASURES: Frequencies of maternal immunologic disorders were compared between cases and controls with a chi2 statistic, and relative risks were estimated by crude and adjusted odds ratios and 95% confidence intervals using logistic regression. RESULTS: The final study population included 407 cases and 2095 controls. A similar proportion of case and control mothers had a diagnosis of any autoimmune disease in the 4-year period surrounding pregnancy (10.3% vs 8.2%, P = .15). After adjustment for maternal factors, only 1 autoimmune condition, psoriasis, was significantly associated with ASDs (adjusted odds ratio, 2.7; 95% confidence interval, 1.3-5.8). A greater than 2-fold elevated risk of ASD was observed for maternal asthma and allergy diagnoses recorded during the second trimester of pregnancy.