Maternal subclinical hypothyroidism during pregnancy is a predisposition for the development of overt hypothyroidism. The influence of maternal thyroid antibodies during pregnancy towards thyroid hormone function of the fetus and consequently neurodevelopmental outcome is still not clear. One single study of Negro et al. showed that euthyroid pregnant women who are positive for thyroid peroxidase antibodies (TPOAb) develop impaired thyroid function, which is associated with an increased risk of miscarriage and premature deliveries. They also showed that substitutive treatment with levothyroxine (LT4) is able to lower the chance of miscarriage and premature delivery.A study of Pop et al. concluded that children of pregnant women who had elevated titers of TPO-Ab but normal thyroid function are at risk for impaired development.Nothing is known about the possible influence of maternal thyroid antibodies towards the development of THOP, although a theoretical link is possible.