Persistent thyroid hormone imbalances in pregnant women receiving care at Soroka University Medical Center in southern Israel may more than double the risk of autism spectrum disorder (ASD) in their children, a new retrospective cohort study has found. The research, led by Idan Menashe of Ben-Gurion University of the Negev in Beer Sheva, analyzed linked electronic health records from Israel’s Clalit Health Services for more than 51,000 singleton births between 2011 and 2017.
Among these pregnancies, 4,409 mothers had abnormal thyroid hormone levels either before conception, during pregnancy, or both. The investigators reported that when chronic thyroid disease was adequately treated and hormone levels remained in the normal range during gestation, autism risk in offspring was not significantly increased, suggesting that effective control of thyroid function can offset potential neurodevelopmental harm. Thyroid dysfunction first arising in pregnancy, without a pre-pregnancy history, also was not clearly linked to higher ASD risk.
The strongest association emerged in women who had thyroid dysfunction both before becoming pregnant and throughout gestation, particularly those with underactive thyroid glands (hypothyroidism) and persistently low hormone levels. In this group, the adjusted hazard of ASD in children was more than doubled, and trimester-specific analysis showed a dose–response pattern: the longer hypothyroidism persisted across one, two, or all three trimesters, the higher the autism risk, with odds more than tripling when low hormone levels were documented in every trimester.
Maternal thyroid hormones play a central role in fetal brain development, especially early in pregnancy when the fetus depends entirely on the mother’s supply. The authors stressed that these findings highlight the need for routine thyroid function screening before and during pregnancy and timely adjustment of thyroid hormone therapy to maintain normal levels throughout gestation, while also calling for further research to clarify risks in women with overactive thyroid disease, who were too few in this cohort to analyze separately.y. The study’s authors emphasized that routine monitoring and timely adjustment of thyroid therapy are essential to maintain normal hormone levels throughout pregnancy and reduce potential neurodevelopmental risks for offspring. They also noted that too few women with overactive thyroid (hyperthyroidism) were included to analyze that group separately, highlighting a gap for future research.
