Maternal hyperthyroidism during pregnancy and offspring risks of attention-deficit/hyperactivity disorder and autism spectrum disorder: A nationwide study

Objective: Thyroid hormones are crucial in normal brain development. Abnormal thyroid hormones in pregnancy may impair neurodevelopment in the offspring. In this study, we intended to determine whether prenatal hyperthyroidism can increase the offspring risk of autism spectrum disorders (ASD) or attention-deficit/hyperactivity disorder (ADHD). Methods: In our study, we identified 330 study pairs (mothers with hyperthyroidism and their children) and 1,320 matched control pairs (mothers without hyperthyroidism and their children) between 1998 and 2008 from the Taiwan Longitudinal Health Insurance. The offspring risk of major neurodevelopmental disorders, including ADHD and ASD, was analyzed in the follow-up period (from childbirth to the end of 2011). Results: The results of logistic regression analysis using adjustment for demographic data and maternal mental health disorders showed that prenatal hyperthyroidism significantly increased the offspring risk of ADHD (odd ratio = 2.23; 95% confidence interval [CI] = 1.19–4.18, p < 0.05) and nonsignificantly increased the risk of ASD (odds ratio = 6.62; 95% CI = 1.08–40.47) after having adjusted for children's demographical data and for maternal mental disorders. Conclusion: Those results suggest that prenatal hyperthyroidism increased the risk of ADHD and ASD in offspring, regardless of demographic conditions and maternal mental health disorders. We suggest that hyperthyroidism in pregnant women should be carefully managed and that additional studies are necessary to clarify the underlying mechanisms which maternal hyperthyroidism leads to neurodevelopmental risks.