**Abstract**

Effects of overt hypothyroidism on pregnancy outcomes and fetal development are well established and treatment protocol is reputable. Subclinical hypothyroidism poses a major health problem in pregnancy. Requirement of iodine increases in pregnancy as demand for synthesis of excess thyroid hormones is there during pregnancy. This is because of fetal dependency on maternal thyroid hormones till 12 weeks of gestation as fetal thyroid tissue is not matured enough to produce adequate hormones for the growing fetus. Hence, dietary iodine deficiency or intake of excess goitrogens in diet can be the major cause of overt and subclinical hypothyroidism in pregnancy. Apart from this autoimmune basis of overt and sub clinical hypothyroidism is also equally important in pregnant women. Data accumulating shows presence of antibodies like anti TPO antibody (anti thyroperoxidase antibody) and anti Tg antibody (anti thyroglobulin antibody) in pregnancy which is associated with increased prevalence of overt and sub clinical hypothyroidism and aggravation of the symptoms associated with it. Studies also document that pregnancy related complications are more prevalent in presence of these autoimmune antibodies. Hence, management of subclinical hypothyroidism in pregnancy also differs in positive and negative cases of anti TPO antibody and anti-Tg antibody.

**Keywords:** sub-clinical hypothyroidism, pregnancy, obstetric outcome, autoimmunity, anti thyroperoxidase antibody (anti TPO antibody), anti-thyroglobulin antibody (anti Tg antibody), assisted fertilization
