In the USA which is considered an iodine
replete country, 2%–3% of apparently healthy, non pregnant women of childbearing age have an elevated serum TSH with the majority in the subclinical range. In southern Iran, the prevalence of hypothyroidism among pregnant women was shown to be 13.7%. In a study carried in India, the prevalence of thyroid dysfunction was high with subclinical hypothyroidism found in 6.47% and overt hypothyroidism found in 4.58% of pregnant women4. Hyperthyroidism is less commonly encountered in pregnancy with a prevalence of 0.2- 0.6%.