OBJECTIVE: Graves' disease in pregnancy carries a risk of fetal thyrotoxicosis from the transplacental transfer of thyroid-stimulating antibodies or fetal hypothyroidism from transplacental transfer of antithyroid drugs and thyroid-blocking antibodies.STUDY DESIGN: From 1991 through 2002, all pregnant women with Graves' disease underwent follow-up evaluations that included serial thyroid-stimulating antibody level, thyroid function, and ultrasound examinations. Umbilical blood sampling was recommended if the thyroid-stimulating antibody level was abnormally high or if fetal tachycardia, goiter, intrauterine growth retardation, or hydrops were present. For fetal hyperthyroidism, the mother received antithyroid drugs; for fetal hypothyroidism, maternal antithyroid treatment was reduced, and thyroxine was injected into the amniotic sac.RESULTS: Of 40000 deliveries, 24 pregnancies (26 fetuses) occurred in 18 women with Graves' disease. Nine of 14 mothers with positive findings elected umbilical blood sampling. In 4 of the mothers, the results were normal. Hyperthyroidism and hypothyroidism were diagnosed in 2 and 3 fetuses, respectively. All the fetuses were treated successfully by the protocol with up to four repeated umbilical blood samplings. No complications were recorded in any of the 20 umbilical blood sampling. In the 5 patients who had only elevated thyroid-stimulating antibody levels and who did not elect umbilical blood sampling, sonographic findings remained normal up to term, and the newborn infants were normal. One of 12 children (in whose case we did not recommend umbilical blood sampling) was born with transient hypothyroidism caused by maternal propylthiouracil treatment. All children, whose cases were followed for up to 9 years, are normal.CONCLUSION: In women with Graves' disease, umbilical blood sampling in selected cases may improve the control of fetal thyroid function.
Amniotic Fluid Antithyroid Agents