Congenital hypothyroidism due to maternal intake of antithyroid drugs

Congenital hypothyroidism due to maternal intake of antithyroid drugs is a condition in which a newborn has reduced thyroid hormone levels caused by the mother's use of antithyroid medications (such as methimazole, carbimazole, or propylthiouracil) during pregnancy. These medications, typically prescribed to treat maternal hyperthyroidism (including Graves' disease), cross the placenta and can suppress the fetal thyroid gland's ability to produce thyroid hormones. This results in a transient form of congenital hypothyroidism in the newborn. The thyroid gland plays a critical role in regulating metabolism, growth, and brain development, particularly during fetal and early neonatal life. Affected newborns may present with a goiter (enlarged thyroid gland), lethargy, poor feeding, prolonged jaundice, constipation, hypothermia, and a hoarse cry. In some cases, the condition may be detected through newborn screening programs that measure thyroid-stimulating hormone (TSH) levels, which are elevated, and low levels of free thyroxine (T4). This condition is generally transient and resolves once the antithyroid drug is cleared from the infant's system, typically within days to weeks after birth. However, prompt recognition and management are essential to prevent potential neurodevelopmental complications. Treatment may include temporary thyroid hormone replacement therapy (levothyroxine) in symptomatic or severely affected neonates until thyroid function normalizes. Close monitoring of thyroid function tests is recommended during the neonatal period and early infancy to guide treatment duration and ensure full recovery.

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