Objectives: This study aims to compare the thyroid function test (TFT) (serum fT3, fT4, TSH) and thyroid peroxidase antibody (anti TPO) between GDM and non GDM pregnant women in the second trimester and to correlate the adverse pregnancy outcomes with TFT in GDM and non GDM women. The gene discussed is TPO; the disease is gestational diabetes.