Thyroid autoimmunity may affect neuropsychological development by interfering with the fetal and/or neonatal thyroid status; indeed, both hypo- and hyperthyroidism during the fetal-neonatal life may be associated with a subsequent impairment of intellectual and psychomotor performances. Maternal thyroid status during early pregnancy, and in particular hypothyroidism due to autoimmune thyroiditis, can also affect the fetal neurological development. Finally, anti-thyroid drugs used to control hyperthyroidism in pregnant women with Graves' disease have been widely investigated for their possible effect on the intellectual development of the offspring.