Maternal hypothyroidism in early pregnancy significantly raises the risk of attention-deficit/hyperactivity disorder (ADHD) in offspring, according to a study published online in the American Journal of Perinatology.
“Our findings make clear that thyroid health likely has a much larger role in fetal brain development and behavioral disorders like ADHD than we previously understood,” said study lead author Morgan R. Peltier, PhD, an associate professor of clinical obstetrics, gynecology, and reproductive medicine at NYU Long Island School of Medicine, New York, New York.
The study included 329,157 children born in Kaiser Permanente Southern California hospitals and followed until age 17. The large-scale investigation, which included participants from diverse ethnic backgrounds, examined a potential link between hypothyroidism during pregnancy and the risk of ADHD in the child.
Overall, 16,696 children in the study were diagnosed with ADHD, researchers reported. Children whose mothers were diagnosed with hypothyroidism shortly before or during the early stages of pregnancy were 24% more likely to receive an ADHD diagnosis, compared with children whose mothers were not diagnosed with hypothyroidism.
The study also found that boys whose mothers had hypothyroidism were 4 times more vulnerable to ADHD than girls whose mothers had hypothyroidism. Furthermore, Hispanic children born to mothers with hypothyroidism had a 45% increased risk of ADHD compared with a 22% increased risk in white children born to mothers with hypothyroidism.
According to the study, maternal hypothyroidism after the first trimester had little effect on the child. By that point, Dr. Peltier said, the fetus may begin producing its own thyroid hormones and, consequently, be less vulnerable to the mother’s thyroid deficiencies.
Peltier MR, Fassett MJ, Chiu VY, Getahun D. Maternal hypothyroidism increases the risk of attention-deficit hyperactivity disorder in the offspring. American Journal of Perinatology. 2020 October 21;[Epub ahead of print].