Serum long acting thyroid stimulator protector in pregnancy complicated by Graves' disease.

Activities of serum long acting thyroid stimulator protector were measured in a series of nine pregnancies in eight mothers who had Graves' disease, one of whom had been successfully treated by surgery. In all but two instances the activities tended to decline as pregnancy progressed. After delivery activities rose in three out of five patients in whom these had disappeared in pregnancy and, as this occurred, the patients relapsed. In the two patients whose activities did not decline thyrotoxicosis persisted throughout pregnancy and after delivery. None of the nine babies in this study suffered from neonatal thyrotoxicosis because maternal activities of the thyroid stimulator protector, though high enough to induce Graves' disease in adults, were not above the threshold for the induction of thyroid overactivity in neonates.