Inadvertent 131I therapy for hyperthyroidism in the first trimester of pregnancy.

Of 963 physicians surveyed to determine therapeutic attitudes toward, and experience with inadvertent radioiodine therapy for hyperthyroidism during the first trimester of pregnancy, 116 physicans (of 517 responding) reported 237 cases. Therapeutic abortion was advised for 55 patients by 22 physicans. From the 182 remaining pregnancies there were two spontaneous abortions, two stillborn, one neonate with biliary atresia, and one with respiratory distress. This complication rate was not greater than might be expected in a similar number of random pregnancies. On the other hand, six infants were hypothyroid (transient for one) and four of these were mentally deficient. Three mothers of hypothyroid infants had received radioiodine therapy in the second trimester. None of the six mothers of hypothyroid infants had had pregnancy tests prior to radioiodine therapy. Survey responses indicate that routine pregnancy testing prior to radioiodine therapy for patients in the child-bearing age is not yet a standard procedure. It should be.