Key takeaways:
- Persistent thyroid hormone imbalance across pregnancy was linked to greater autism risk in offspring.
- Risk increased with the number of trimesters affected by maternal thyroid dysfunction.
- Combined chronic and gestational thyroid disorders showed the strongest association with ASD.
- Isolated chronic or gestational thyroid dysfunction alone was not significantly associated with increased ASD risk.
- Findings support routine thyroid monitoring and timely treatment adjustments during pregnancy.
Researchers have identified increased odds of autism in offspring of women with persistent thyroid hormone imbalance across pregnancy, publishing their findings in The Journal of Clinical Endocrinology & Metabolism.1
There were more than 51,000 births assessed, and autism was more often reported in children whose mothers had persistent thyroid hormone imbalance. Additionally, a longer duration of thyroid dysfunction across trimesters was associated with a greater risk.
“We found that while adequately treated chronic thyroid dysfunction was not associated with increased autism risk in offspring, ongoing imbalance across multiple trimesters was,” said Idan Menashe, PhD, from the Ben-Gurion University of the Negev. “These findings underscore the need for routine monitoring and timely adjustment of therapy.”
Classification of thyroid dysfunction
The retrospective cohort study was conducted to evaluate the link between maternal thyroid dysfunction during pregnancy and offspring autism spectrum disorder (ASD) risk.2 Members of Clalit Health Services (CHS) were included between January 2011 and December 2017, with follow-up lasting until January 2021.
Sociodemographic and chronic diagnoses data was obtained from the CHS electronic database. This was linked to the database of the medical center where the study was conducted for prenatal and perinatal data, alongside the Azrieli National Center for Autism and Neurodevelopment Research database for ASD diagnoses.
Thyroid dysfunction was classified as chronic, gestational, or both, with diagnoses determined by International Classification of Diseases, Ninth Revision codes. The type of thyroid dysfunction was based on TSH and early-pregnancy free T4 values measured each trimester. These values also allowed investigators to distinguish between gestational hypothyroidism and gestational hyperthyroidism.
Higher ASD risk with combined chronic and gestational dysfunction
There were 51,296 women included in the final analysis, 4409 of whom were diagnosed with abnormal thyroid function, 1161 chronic hypothyroidism, 1600 gestational hypothyroidism, and 1054 both. Chronic hyperthyroidism was also reported in 100, gestational hyperthyroidism in 376, and both in 15.
Offspring were aged a median 4.6 years at ASD diagnosis. Among offspring born to mothers with both chronic and gestational thyroid dysfunction, a significantly increased cumulative ASD incidence was reported vs those whose mothers had normal thyroid function.
However, no significant difference was observed for offspring of mothers with only chronic or gestational thyroid dysfunction, with an adjusted hazard ratio (aHR) of 1.33. In comparison, the aHR for ASD risk in offspring of women with both types of thyroid dysfunction was 2.68, indicating an over 2-fold increase in risk.
Women with both chronic and gestational hypothyroidism also reported a significant increase in risk, with an aHR of 2.61. However, nonsignificant aHRs of 0.47 and 1.19 were reported for chronic-only and gestational-only hypothyroidism, respectively.
Trimester-specific risk patterns
A rise in offspring ASD risk between 28% and 39% was reported for each additional trimester of maternal thyroid dysfunction. A single trimester of thyroid dysfunction was linked to an aHR of 1.69 for offspring ASD, vs 2.39 for 2 trimesters and 3.25 for the full pregnancy. In women with both chronic and gestational hypothyroidism, these aHRs were:
- 1.35 for exposure during 1 trimester
- 2.04 for any time in 2 trimesters
- 2.87 for a duration of all 3 trimesters
Overall, these results indicated a link between maternal thyroid hormone concentrations during pregnancy and offspring ASD risk. However, no association was reported for chronic hypothyroidism alone.
“While causal conclusions are premature, these results are consistent with recommendations for routine monitoring of thyroid hormone levels and treatment of imbalanced thyroid function with thyroid hormone medications to maintain euthyroidism in pregnancy,” wrote investigators.
References
- Thyroid dysfunction during pregnancy may increase autism risk in children. The Endocrine Society. November 25, 2025. Accessed December 9, 2025. https://www.eurekalert.org/news-releases/1106734?
- Elbedour L, Weinberg M, Meiri G, Michaelovski A, Menashe I. Maternal thyroid hormone imbalance and risk of autism spectrum disorder. The Journal of Clinical Endocrinology & Metabolism. 2025. doi:10.1210/clinem/dgaf596
