Hypothyroidism in mothers tied to heightened risk of developing autism in children
Maternal hypothyroidism contributes to an increased risk of developing autism spectrum disorder (ASD) in children in a manner dependent on race–ethnicity, according to a retrospective US cohort study.
The study included 397,201 children who were delivered from 1991 to 2011 and remained Kaiser Permanente Southern California health plan members from 1993 to 2014. During the study period, the prevalence of chronic hypothyroidism in mothers was 2.2 percent. There were 6,475 children who developed ASD. Mothers of children with ASD were older, better educated, at lower parity and received prenatal care earlier, and their children were born earlier and more often males of white race.
ASD rates were higher in children born to hypothyroid mothers than in children born to those without the diagnosis (2.14 vs 1.62/1,000 person-years). In Cox proportional hazards models, maternal hypothyroidism, whether diagnosed before or during pregnancy, increased the risk of ASD in offspring by about 30 percent (adjusted hazard ratio [HR], 1.31; 95 percent CI, 1.13–1.53).
The association between maternal hypothyroidism and ASD was seen among both boys (3.93 vs 2.62/1,000 person-years; adjusted HR, 1.27; 1.07–1.50) and girls (1.10 vs 0.61/1,000 person-years; adjusted HR, 1.51; 1.10–2.08). Among women diagnosed with hypothyroidism during pregnancy, normal thyroid-stimulating hormone and free thyroxine levels were not associated with an increased risk of ASD in children.
Prenatal hypothyroidism was associated with an increased risk of ASD in children of Hispanics (adjusted HR, 1.09; 1.01–1.17) and women of other/mixed race–ethnicity (adjusted HR, 1.08; 1.00–1.16) than in children of white women.
According to researchers, management of maternal hypothyroidism may help ameliorate the risk of ASD.