Recommendations for thyroxin therapy during pregnancy

Disorders of thyroid function are common among women of childbearing age. It is known that thyroid physiology normally alters during gestation. Clinicians, often, overlook thyroid dysfunction in pregnant women because of nonspecific symptoms and the hypermetabolic state of normal pregnancy. After all, the clinician must consider thyroid dysfunction as a possibility in pregnant women and differentiate normal physiological changes from thyroid disease. Abnormalities of maternal thyroid function can affect the fetus directly or indirectly. The fetal thyroid begins to produce thyroid hormones after the first trimester, so the critical thyroid hormones for fetal brain development must be supplied by the mother. It is of interest how sensitive the fetus is to decreases in circulating maternal thyroid hormones and in maternal thyrotoxicosis. Over recent years there has been an expansion of knowledge regarding thyroid disease in pregnancy and subsequently controversies about management of thyroid disease in pregnancy. This review focuses on maternal overt and subclinical hypothyroidism in pregnancy, suggesting guidelines for appropriate treatment for this disease due to its frequency, especially the subclinical manifestation, and the controversy that exists. It also reviews the complications in mother and fetus when hypothyroidism is untreated. On the other hand, with respect to other differing opinions, some recommendations should be given by the authors about supplying thyroxin to pregnant women with thyroid disease other than hypothyroidism.