Postpartum recurrence of Graves’ hyperthyroidism can be prevented by the continuation of antithyroid drugs during pregnancy

Summary objective Previous studies recommend the discontinuation of antithyroid drug (ATD) therapy during pregnancy in women with well‐controlled Graves’ hyperthyroidism (GH). In this study, we investigated whether this termination of ATD therapy during pregnancy is beneficial in terms of postpartum GH recurrence. design A nonrandomized , retrospective study. patients Sixty‐five pregnant GH patients treated with maintenance doses of ATDs were assigned into two groups: ATD therapy was discontinued before delivery in Group 1, but continued during pregnancy and after delivery in Group 2. measurements The prevalence of postpartum recurrence or exacerbation of GH within 1 year after delivery was examined. Serum T4, T3 TSH, and TSH receptor antibody levels were measured. results In Group 1, 70·8% (17/24) of patients suffered a recurrence of GH within 1 year after delivery. In contrast, a postpartum exacerbation of GH was observed in only 29% (12/41) of patients in Group 2 ( P  < 0·01). Both exacerbations and recurrences of GH appeared primarily within 4–6 months after delivery. Apparent neonatal hypothyroidism and malformations were not observed in the offspring of either group. conclusion Continuing antithyroid drug therapy throughout pregnancy prevents postpartum recurrence of Graves’ hyperthyroidism without resulting in neonatal hypothyroidism or malformations.