Preventing intellectual disability during pregnancy: what are the potentially high yield targets?

OBJECTIVE: To identify risk factors among children with unknown cause intellectual disability (ID) and to estimate the population-attributable risk (PAR) associated with these factors. METHODS: This was a retrospective cohort study of maternal and child pairs born between 2004 and 2010 in South Carolina, and information was obtained from Medicaid billing records, birth certificates, and other administrative data. The data included 123,922 children and logistic generalized estimating equations (GEE) regression models were used to estimate the association of maternal risk factors and ID. We estimated models with and without birth weight as a covariate, since low birth weight is known to be a mediator of the association between some risk factors and ID in children. RESULTS: The prevalence of ID in the children was 3.85% and the associations between risk factors and ID were similar for female and male children. We found that the odds of having ID were increased if a child's mother had a diagnosis of major depression; for male children, the odds ratio (OR) was 1.34 (95% confidence interval [CI] 1.14-1.59, PAR 2.17%); and for females, the OR was 1.59 (95% CI 1.30-1.95, PAR 4.70%). The odds of having ID were also increased for children of women with bipolar disorder (males - OR 1.95, 95% CI 1.53-2.48, PAR 2.85%; females - OR 1.63, 95% CI 1.20-2.22, PAR 2.05%). CONCLUSIONS: Major maternal depression and bipolar disorder were each significantly associated with the odds of ID in children, each accounting for approximately 2-5% of the PAR, when controlling for covariates.