Thyroid Disorders

Thyroid disease during pregnancy is common, second only to diabetes amongst endocrine disorders. The overlap between common pregnancy complaints and physiological changes and the signs and symptoms of both hyperthyroidism and hypothyroidism can make recognition of disease challenging. Worldwide, iodine deficiency remains the most common etiology for maternal hypothyroidism and is the leading cause of offspring intellectual deficits. Hyperthyroidism affects approximately 0.2% of pregnancies. The overwhelming majority of such women have preexisting Graves disease. Subclinical hyperthyroidism is well tolerated during pregnancy. In older women it may be associated with cardiac arrhythmias but no significant adverse outcomes have been identified during pregnancy. Pharmacotherapy management of overt maternal hyperthyroidism alleviates maternal and fetal risks, but may result in unintentional fetal hypothyroidism due to placental transfer of the antithyroid medication. Titrating therapy to achieve a euthyroid state bordering upon subclinical hyperthyroidism is ideal as it is well tolerated.