Thyroid Disease in Pre- and Post-Pregnancy

Thyroid dysfunction affects approximately 3% of pregnant women. Adequate thyroid hormone levels are important for fetal development. Normal physiological changes of pregnancy can contribute to subclinical hypothyroidism which may require treatment with thyroxine during pregnancy. Pre-existing hypothyroidism requires an increase in thyroxine dosage. Pre-existing hyperthyroidism may or may not require continued treatment with anti-thyroid medication, though these medications can rarely cause adverse fetal effects. Gestational hyperthyroidism must be distinguished from a new diagnosis of Graves’ disease in pregnancy. Gestational hyperthyroidism does not require treatment with anti-thyroid medication. Graves’ disease requires additional monitoring of mother and fetus and consideration of anti-thyroid medication. Post-partum thyroiditis is an underdiagnosed condition which can cause transient hyperthyroidism before recovery or hypothyroidism, or hypothyroidism without a hyperthyroid phase. Serial monitoring of thyroid function test is required. The vast majority of women with thyroid conditions can be managed to a successful pregnancy outcome.