Israeli Study Finds Link Between Maternal Thyroid Levels and Autism Risk

Thyroid hormones play a central role in fetal brain development, particularly during the early stages when the fetus depends entirely on the mother’s hormonal supply.

By Shula Rosen

A large Israeli study tracking more than 51,000 births has found that women with untreated, persistent thyroid hormone imbalance during pregnancy were 2.5 times more likely to have children later diagnosed with autism, while those whose thyroid levels were kept stable did not face the same risk.

The research was carried out at the Azrieli National Center for Autism at Ben-Gurion University of the Negev and followed births at Soroka Medical Center. The findings were published this month in the Journal of Clinical Endocrinology & Metabolism.

Researchers focused on thyroid hormone levels throughout pregnancy, examining cases in which abnormal levels of TSH and T4 were detected through routine prenatal blood tests. Thyroid hormones play a central role in fetal brain development, particularly during early stages when the fetus depends entirely on the mother’s hormonal supply.

The data showed a clear distinction between temporary or treated thyroid conditions and hormone imbalances that persisted across pregnancy.

Only children born to mothers whose thyroid levels remained abnormal over time showed a significantly higher rate of autism diagnoses. The risk increased further the longer the imbalance went uncorrected.

“We found that the risk of autism existed only in the offspring of women with persistent thyroid hormone imbalance throughout pregnancy. In contrast, women with chronic thyroid problems who were properly treated did not have an increased risk of autism in their children,” Prof. Idan Menashe, the study’s lead researcher, said in an interview with The Jerusalem Post. “These findings emphasize the need for routine monitoring and real-time treatment adjustments to maintain normal thyroid hormone levels throughout pregnancy.”

Thyroid dysfunction during pregnancy is relatively common and can reflect either an underactive or overactive thyroid. Both conditions are typically manageable through medication that restores hormone levels to the normal range, making early detection and consistent follow-up clinically achievable.

The researchers cautioned that the study does not suggest thyroid imbalance alone causes autism, but rather identifies a significant risk factor that may interact with other biological and environmental influences. Autism spectrum disorder is a complex neurodevelopmental condition that affects communication, social interaction, and sensory processing.

“Further research is needed to understand how this type of hormonal imbalance leads to disruption in fetal neural development and ultimately to autism,” Prof. Menashe said.

The findings reinforce the importance of sustained prenatal care and hormone monitoring, offering a potential pathway to reduce autism risk through timely medical intervention.