Birth defects linked to antithyroid drug treatment in pregnancy have for a long time been known to exist. Antithyroid drugs, in this context, include methimazole (MMI), carbimazole (CMZ) and propylthiouracil (PTU).
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Epidemiology
The prevalence of birth defects appears to be high in children exposed to ATD in early pregnancy. Both MMI/CMZ and PTU are associated with an increased odds ratio of birth defects, with an odds ratio approximating 2. The commonest defects in MMI/CMZ-exposed children seem to appear with an adjusted odds ratio ~20 when combined 2.
Clinical presentation
MMI/CMZ-exposed children may commonly develop:
omphalomesenteric duct anomalies
aplasia cutis
Both MMI/CMZ and PTU have been shown to be associated with urinary system malformation. Moreover, PTU may predominantly cause malformations in the face and neck region.
Pathology
Hyperthyroidism in pregnant women is a known source of a variety of maternal and fetal complications, necessitating the use of antithyroid drug treatment in pregnancy to control maternal hormone levels.