Birth defects linked to antithyroid drug treatment in pregnancy
Birth defects linked to antithyroid drug treatment in pregnancy have for a long time been known to exist. A recent Danish register-based cohort study has assessed the degree of association of antithyroid drugs (ATD), such as methimazole (MMI) / carbimazole (CMZ) and propylthiouracil (PTU), and the spectrum of disease.
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 (OR) approximating 2. The commonest defects in MMI/CMZ-exposed children seem to appear with an adjusted OR ~20 when combined 2.
MMI/CMZ-exposed children may commonly develop:
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.
Hyperthyroidism in pregnant women is a known source of a variety of maternal and fetal complications, necessitating the use of antithyroid drug treatment (ATD) in pregnancy to control maternal hormone levels.
- 1. Foulds N, Walpole I, Elmslie F et-al. Carbimazole embryopathy: an emerging phenotype. Am. J. Med. Genet. A. 2005;132A (2): 130-5. doi:10.1002/ajmg.a.30418 - Pubmed citation
- 2. Andersen SL, Olsen J, Wu CS et-al. Birth defects after early pregnancy use of antithyroid drugs: a Danish nationwide study. J. Clin. Endocrinol. Metab. 2013;98 (11): 4373-81. doi:10.1210/jc.2013-2831 - Pubmed citation