Maternal hyperthyroidism and congenital malformation in the offspring

Area of Science:

• Endocrinology
• Obstetrics
• Pediatrics

Background:

• Graves' disease in pregnant individuals poses risks to fetal development.
• Maternal thyroid status and medication use during pregnancy require careful consideration for congenital anomaly prevention.

Purpose of the Study:

• To compare the incidence of congenital malformations in neonates exposed to maternal hyperthyroidism versus methimazole (MMI) during the first trimester.
• To evaluate the safety and efficacy of MMI treatment in pregnant individuals with Graves' disease.

Main Methods:

• A cohort of 643 neonates from mothers with Graves' disease was analyzed.
• Infants were categorized into four groups based on maternal thyroid status (hyperthyroid or euthyroid) and MMI treatment (received or not received) during the first trimester.
• Prevalence of major external malformations was compared across the four groups.

Main Results:

• The prevalence of malformations was significantly higher in infants of untreated hyperthyroid mothers (6.0%) compared to untreated euthyroid mothers (0.3%).
• Infants exposed to MMI showed lower malformation rates (1.7% in hyperthyroid mothers, 0.0% in euthyroid mothers) than untreated hyperthyroid mothers.
• No clear dose-dependent relationship was observed between MMI exposure and malformation occurrence.

Conclusions:

• Uncontrolled maternal hyperthyroidism during the first trimester is associated with an increased risk of congenital malformations.
• Methimazole treatment for Graves' disease in pregnancy appears to be beneficial, with its protective effects potentially outweighing any teratogenic risks.
• Effective management of maternal thyroid status is crucial for optimizing fetal outcomes.