[Neonatal hyperthyroidism secondary to Basedow's disease in the mother]

Neonatal hyperthyroidism is only seen in children whose mothers had an autoimmune thyroid disease. In these women, thyroid stimulating immunoglobulins (TSI) must be assayed during pregnancy, so that the newborn can be taken care of immediately. Contrary to thyroid hormones, TSI cross the placental barrier and are responsible for thyrotoxicosis; regular monitoring of their decrease in the newborn indicates that these antibodies are of maternal origin. In both mother and child, the treatment of choice is a synthetic antithyroid drug.