Thyroid dysfunction in pregnancy

Maternal thyroid state is an important predictor of pregnancy outcome. Both hyperthyroidism and hypothyroidism have been shown to have an adverse impact on pregnancy. There is a wide range in the prevalence of thyroid dysfunction worldwide. 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 range12. In southern Iran, the prevalence of hypothyroidism among pregnant women was shown to be 13.7%3. 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 0.20.6%5.