Deranged thyroid function tests are commonly encountered in pregnancy. Thyroid dysfunction is the second most frequent endocrine diseases among reproductive-aged women. Study in hypothyroidism has increased over the past few years as it affects development and growth in the offspring and can cause adverse effects on pregnancy outcome. A lot of research has been going on recently on the impact of subclinical hypothyroidism (SCH) on pregnancy outcome. Although the effect of clinical hypothyroidism on pregnancy is well known and replacement therapy is strongly recommended, but doubt exists about the effects of subclinical hypothyroidism and its need for replacement in pregnancy. This has led to much health organization to recommend routine thyroid screening in pregnancy.