The significance of TRAb titers in pregnant women TRAb titers are a major marker of Graves’ disease activity. An elevated TRAb titer suggests the possibility of (1) fetal hyperthyroidism, (2) neonatal hyperthyroidism, (3) fetal hypothyroidism, (4) neonatal hypothyroidism, and (5) central hypothyroidism. The development of these complications is dependent on the following factors: (1) poorly controlled hyperthyroidism during pregnancy may induce transient fetal central hypothyroidism; ( 2) excessive ATD is associated with fetal and neonatal hypothyroidism; (3) high titers of TRAb at 22-26 weeks of gestation are a risk factor for fetal or neonatal hyperthyroidism; (4) 95% of active Graves’ hyperthyroidism has elevated TRAb titers and persists after thyroidectomy. (4) 95% of active Graves’ hyperthyroidism has elevated TRAb titers and remains elevated after thyroidectomy. Indications for TRAb monitoring in pregnancy with Graves’ disease include (1) active hyperthyroidism in the mother, (2) history of radioactive iodine therapy, (3) history of delivery of a hyperthyroid infant, and (4) previous thyroidectomy for hyperthyroidism during pregnancy. The incidence of fetal and neonatal hyperthyroidism in pregnant women with active Graves’ disease or a history of prior Graves’ hyperthyroidism is 1% and 5%, respectively, and failure to diagnose and treat the condition in a timely manner increases the incidence of fetal/neonatal hyperthyroidism and mortality. Measurement of serum TRAb at 24-28 weeks of gestation is useful in assessing pregnancy outcome. A TRAb more than 3 times the upper reference value suggests the need for close fetal follow-up, preferably in collaboration with the treating physician. Therefore, testing at 24 to 28 weeks of gestation has been recommended because antibody concentrations generally begin to decrease by 20 weeks of gestation.