Endemic goitre is a socially important disease in many regions of Italy. In conditions of euthyroidism, the course of pregnancy and perinatal outcome are not burdened by significant complications. It is useful to control thyroid function and to start L-thyroxine therapy in order to avoid any further increase in thyroid size owing to the goitrogenic effect of pregnancy and to avoid transient hypothyroidism and the nodular evolution of goitre. Recent studies appear to indicate a possible physiological role for thyroid hormones in the development of the fetal CNS as early as conception, an additional motive for the administration of thyroxine in order to prevent pathologies caused by thyroid hormone deficiency in utero.