Hyperthyroidism in twin pregnancies involving a hydatidiform mole and a coexisting live fetus is a rare condition requiring careful management. We present a 34-year-old pregnant woman at 12 weeks' gestation with severe nausea, vomiting, and mild vaginal bleeding. A transvaginal ultrasound revealed a dichorionic diamniotic twin pregnancy with 1 normal fetus and 1 hydatidiform mole, leading to hyperthyroidism from elevated β human chorionic gonadotropin levels. Conservative management without antithyroid medications, combined with regular monitoring, allowed the pregnancy to continue to term, resulting in the delivery of a healthy baby at 39 weeks. Postpartum management required treatment of retained products of conception. This case highlights the complexities in the management of complications for both mother and fetus.
Keywords: hydatidiform mole; hyperthyroidism; living fetus; twin pregnancy.
© The Author(s) 2025. Published by Oxford University Press on behalf of the Endocrine Society.