Aims. To establish the prevalence and the effect of thyroid dysfunction on pregnancy outcomes in Asian-Indian population. Subjects and Methods. The study cohort comprised of 483 consecutive pregnant women in the first trimester attending the antenatal clinic of a tertiary center in Mumbai, India. Thyroid hormone levels and thyroid peroxidase antibody were estimated. Patients with thyroid dysfunction were assessed periodically or treated depending on the severity. Subjects were followed until delivery. Results. The prevalence of hypothyroidism, Graves' disease, gestational transient thyrotoxicosis, and thyroid autoimmunity (TAI) was 4.8% (n = 24), 0.6% (n = 3), 6.4 % (n = 31), and 12.4% (n = 60), respectively. Forty percent of the hypothyroid patients did not have any high-risk characteristics. Hypothyroidism and TAI were associated with miscarriage (P = 0.02 and P = 0.001, resp.). Conclusions. The prevalence of hypothyroidism (4.8%) and TAI (12.4%) is high. TAI and hypothyroidism were significantly associated with miscarriage.