Hyperthyroidism and Birth Defects: The Roles of Maternal Thyroid Function and Thyroid Autoantibody Positivity

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Pediatrics

Background:

• Maternal hyperthyroidism is linked to birth defects, but the specific roles of thyroid function and autoimmunity remain unclear.
• Understanding these associations is crucial for prenatal care and risk assessment.

Purpose of the Study:

• To investigate the relationship between maternal thyroid function, thyroid autoantibodies, and the occurrence of birth defects in offspring.
• To clarify the impact of thyroid health during early pregnancy on fetal development.

Main Methods:

• A retrospective cohort study involving 20,399 pregnant women without prior thyroid disease.
• Analysis of maternal blood samples for thyroid-stimulating hormone (TSH), free thyroxine (fT4), and various thyroid autoantibodies (TPO-Ab, Tg-Ab, TRAb, TSI).
• Retrieved birth defect data from hospital diagnoses.

Main Results:

• No significant difference in maternal TSH or fT4 levels was observed between children with and without birth defects.
• Birth defect prevalence was similar in mothers with or without thyroid peroxidase antibodies (TPO-Ab) or thyroglobulin antibodies (Tg-Ab).
• A higher prevalence of birth defects (9.5%) was noted in children of mothers positive for TSH-receptor antibodies (TRAb) or thyroid stimulating immunoglobulin (TSI).

Conclusions:

• Maternal thyroid function in early pregnancy is not associated with an increased risk of birth defects.
• Maternal thyroid stimulating antibodies (TRAb/TSI) may be linked to a higher risk of birth defects, meriting further investigation.
• These findings contribute to understanding thyroid autoimmunity in pregnancy and its potential impact on infant health.