Fetal Hyperthyroidism: Intrauterine Treatment with Carbimazole in Two Siblings

Hyperthyroidism can manifest very early in fetal life (fetal thyrotoxicosis) or immediately after birth (neonatal thyrotoxicosis). The authors describe outcome of pregnancies in a woman with Graves' disease who received medical management and underwent subtotal thyroidectomy. The first pregnancy resulted in macerated stillbirth at 32 wk. Fetal tachycardia was followed by intrauterine death at 30 wk in the second pregnancy and macerated stillbirth at 26 wk in the third pregnancy. Fetal tachycardia was detected at 17 wk in the fourth pregnancy. Treatment with carbimazole along with thyroxine was followed by a live birth at 35 wk; but the baby developed severe fatal neonatal thyrotoxicosis with crisis on day 9 and died on day 12. Fetal tachycardia was noted in the fifth pregnancy as well and she was treated with carbimazole and thyroxine. She delivered a male baby at 37 wk. He developed neonatal hypothyroidism on day 8 which was controlled with thyroxine.