Background: The thyroid undergoes physiological changes during pregnancy, such moderate enlargement of the gland and increasing of vascularization. Objective: To study maternal and fetal complications during pregnancy related with thyroid disorders. Methods: The present Prospective observational study was undertaken in obstetrics and gynaecology OPD IPGME&R, S.S.K.M.Hospital, Kolkata, during the periods from February 2015 to July 2016 in collaboration with department of ENDOCRINOLOGY. Results: Even after receiving adequate L-troxin supplementation throughout their pregnancies, hypothyroid patient are more prone to anemia, PPH, APH, Eclampsia, lactation failure, puerperal pyrexia. In TPO –Ab positive cases incidence of these complications ismore than TPO-Ab negative cases. IUGR, preterm delivery and early trimesterare common fetal complications in hypothyroidism in pregnancy. In TPO-Ab positive cases these complications occur more frequently than TPO-Ab negative cases. There is increased incidence of LSCS in pregnancy with thyroid disorders mainly with hyperthyroidism n hypothyroidism due to hypertensive complication, IUGR and fetal distress. There is increase incidence of fetal distress, low birthweight ,neonatal jaundice ,sepsis, diarrhoea. Conclusions: Patients with subclinical hypothyroidism remain a symptomatic, but have bad obstetric and neonatal outcome, although less severe than overt hypothyroidism cases.