Subclinical hypothyroidism in the first trimester of pregnancy in North India.

Subclinical hypothyroidism based on population and trimester specific cut-offs is reported to complicate 1-2% of all pregnancies. Using the recent Endocrine Society guidelines of 2.5 mIU/L of Thyroid Stimulating Hormone as the upper level of normal in the first trimester the reported prevalence of subclinical hypothyroidism is much higher. Recent publications have also emphasized that there is considerable racial variation in the prevalence of thyroid disorders in pregnancy. Among published literature North Indian women appear to have the highest rates of subclinical hypothyroidism in the first trimester of pregnancy. More widespread use of universal screening and trimester specific ranges in pregnancy for thyroid hormonal assays will lead to a large number of North Indian women requiring treatment for thyroid disorders in pregnancy.