Introduction: Although for thyroid disorders are the second most prevalent endocrine abnormalities among reproductive aged women, the signs and symptoms of thyroid disease can often be masked by the physiologic changes of pregnancy. The aim of this study was to identify  physiological signs and symptoms common to both pregnancy and thyroid disorders among a community based sample of pregnant women without thyroid dysfunction. Materials and Methods: This population-based cross-sectional study was conducted on 1600 pregnant women. A comprehensive questionnaire including questions regarding the signs and symptoms of thyroid disease was completed for subjects and relevant clinical examinations were conducted. Blood samples were taken and serum thyroxine (T4), T-uptake, thyrotropin (TSH) and thyroid peroxidase antibodies (TPO-Ab) were measured. Results: Of study participants, 63.5% had normal thyroid function. The prevalence of overt hypothyroidism and hyperthyroidism were 3.8%, and 0.8%, respectively and 29.8% of patients had subclinical hypothyroidism. Of pregnant women without thyroid dysfunction, 64.8% had one or more of the signs and symptoms of thyroid disorders. Most common symptoms were fatigue (30.3%), followed by lethargy and drowsiness (20.3%). Conclusion: Normal physiological changes of pregnancy can mimic some of the signs and symptoms of thyroid disorders. The results indicated that over half of the healthy pregnant women experienced one or more of the signs and symptoms of thyroid disorders during pregnancy. Correct interpretation of signs and symptoms of thyroid dysfunction during normal pregnancy is critical to discriminate between physiologic and pathological changes.