Fetal methimazole syndrome

Fetal Methimazole Syndrome is a rare condition affecting newborns, resulting from the exposure to methimazole during pregnancy. Methimazole is a medication primarily used to treat hyperthyroidism, a condition where the thyroid gland is overactive. While effective for managing hyperthyroidism, methimazole can cross the placental barrier and affect the developing fetus, leading to a range of congenital anomalies and developmental issues collectively known as Fetal Methimazole Syndrome.

Causes

The primary cause of Fetal Methimazole Syndrome is the maternal intake of methimazole during pregnancy, especially during the first trimester, which is a critical period for fetal development. Methimazole is known to interfere with the normal development of the fetus, leading to various anomalies.

Symptoms and Features

Fetal Methimazole Syndrome is characterized by a spectrum of clinical features and anomalies, including:

• Aplasia cutis congenita, a condition where a newborn is missing skin from certain areas of the body, often on the scalp.
• Choanal atresia, a blockage of the nasal passage.
• Esophageal atresia, an abnormality in which the esophagus does not develop properly.
• Umbilical hernia or inguinal hernia, which are types of hernias commonly seen in affected infants.
• Developmental delays and intellectual disabilities in some cases.
• Facial dysmorphisms, such as a small nose, low-set ears, and a small head (microcephaly).

Diagnosis

Diagnosis of Fetal Methimazole Syndrome is primarily based on the presence of characteristic clinical features and a history of maternal methimazole use during pregnancy. Prenatal imaging techniques, such as ultrasound, may detect some of the physical anomalies before birth. However, a definitive diagnosis is usually made after birth based on the newborn's physical examination and medical history.

Management and Treatment

Management of Fetal Methimazole Syndrome involves a multidisciplinary approach to address the various anomalies and developmental issues. This may include:

• Surgical interventions for conditions like choanal atresia and esophageal atresia.
• Supportive care for skin defects, such as aplasia cutis congenita.
• Regular monitoring and supportive therapies for developmental delays and intellectual disabilities.
• Counseling and support for families affected by the syndrome.

Prevention

The best approach to prevent Fetal Methimazole Syndrome is the careful management of maternal hyperthyroidism during pregnancy. Alternatives to methimazole, such as propylthiouracil (PTU), may be considered during the first trimester, although PTU also carries risks and should be used under close medical supervision. The key is a balanced approach to managing maternal health while minimizing risks to the fetus.