Maternal Thyroid Hormone Dysregulation and Autism Spectrum Disorder Risk
Overview
This retrospective cohort study of 51,296 singleton births found that persistent maternal hypothyroidism across pregnancy trimesters is associated with increased autism spectrum disorder (ASD) risk in offspring. Adequately treated chronic hypothyroidism alone was not linked to elevated ASD risk.
Background
Maternal thyroid hormones are critical for fetal brain development, especially during the first trimester when the fetus depends on maternal hormone supply. Thyroid dysfunction during pregnancy has been implicated in adverse neurodevelopmental outcomes, including cognitive delays and potentially ASD. Prior studies have shown inconsistent results regarding the association between maternal thyroid abnormalities and ASD, highlighting the need for further investigation. This study explores the relationship between maternal thyroid dysfunction during gestation and ASD diagnosis in offspring within a large, ethnically diverse population.
Data Highlights
Maternal Thyroid Status
Number of Mothers (%)
Adjusted Hazard Ratio (aHR) for ASD
95% Confidence Interval (CI)
Normal Thyroid Function
46,887 (91.4%)
Reference
–
Abnormal Thyroid Function
4,409 (8.6%)
Not significantly different (log-rank P = .27)
–
Chronic Hypothyroidism Only (likely treated)
Not specified
0.47
0.15–1.48
Combined Chronic and Gestational Hypothyroidism
Not specified
2.61
1.44–4.74
Hypothyroidism Exposure by Trimesters
1 trimester
1.69
1.19–2.83
2 trimesters
2.39
1.24–5.78
3 trimesters
3.25
1.07–7.21
Key Findings
8.6% of mothers exhibited abnormal thyroid function during pregnancy.
ASD cumulative incidence did not differ significantly between offspring of mothers with normal versus abnormal thyroid function overall.
Chronic hypothyroidism alone, likely reflecting adequate treatment, was not significantly associated with increased ASD risk (aHR 0.47; 95% CI 0.15–1.48).
Combined chronic and gestational hypothyroidism was associated with a significantly higher ASD risk (aHR 2.61; 95% CI 1.44–4.74).
A dose-response relationship was observed: longer duration of hypothyroidism exposure across trimesters correlated with progressively higher ASD risk (up to aHR 3.25 for exposure in all three trimesters).
Clinical Implications
These findings emphasize the importance of routine thyroid function screening throughout pregnancy and timely management of hypothyroidism to mitigate ASD risk in offspring. Adequate treatment of chronic hypothyroidism appears to reduce the risk, whereas persistent untreated or inadequately treated hypothyroidism across gestation increases ASD likelihood. Clinicians should monitor thyroid status closely during all trimesters to optimize neurodevelopmental outcomes.
Conclusion
Persistent maternal hypothyroidism during pregnancy is associated with increased ASD risk in offspring, while adequately treated chronic hypothyroidism is not. This underscores the critical need for continuous thyroid monitoring and management throughout gestation.
References
Study Authors/2024 -- The Link Between Maternal Thyroid Hormone Dysregulation and Autism Spectrum Disorder Risk
