Thyroid disorders in pregnancy

Thyroid disorders are common in pregnancy and the most common disorder is subclinical hypothyroidism. Due to the complex hormonal changes during pregnancy, it is important to remember that thyroxine requirements are higher in pregnancy. According to recent American Thyroid Association (ATA) guidelines, the recommended reference ranges for TSH are 0.1 to 2.5 mIU/L in the first trimester, 0.2 to 3.0 mIU/L in the second trimester, and 0.3 to 3.0 mIU/L in the third trimester. Maternal hypothyroidism is an easily treatable condition that has been associated with increased risk of low birth weight, fetal distress, and impaired neuropsychological development. Hyperthyroidism in pregnancy is less common as conception is a problem. Majority of them are due to Graves’ disease, though gestational hyperthyroidism is to be excluded. Preferred drug is propylthiouracil (PTU) with the target to maintain free T4 in upper normal range. Doses can be reduced in third trimester due to the immune-suppressant effects of pregnancy. Early and effective treatment of thyroid disorder ensures a safe pregnancy with minimal maternal and neonatal complications.