Obstetric management of thyroid disease

Timely treatment of thyroid disease during pregnancy is important in preventing adverse maternal and fetal outcome. At present, thyroid testing is performed on symptomatic pregnant women or those with a history of the disease. Hypothyroidism is very often subclinical in nature and not easily recognized without specific screening programs. Even mild maternal thyroid hormone deficiency may lead to neurodevelopment complications in the fetus. Early maternal thyroxine therapy might be beneficial in these women. The main diagnostic indicator of thyroid disease is the measurement of serum thyroid stimulating hormone and free thyroxine. Availability of gestation-age-specific thyroid stimulating hormone (TSH) thresholds is an important aid in the accurate diagnosis and treatment of thyroid dysfunction. Pregnancy-specific free thyroxine thresholds not presently available are also required. Gestational iodine deficiency is still prevalent in some areas of the United Kingdom. Thyroid peroxidase antibody (TPO Ab) in combination with thyroglobulin autoantibody (TgAb) is an accurate predictor of postpartum thyroiditis (PPT). Early screening and treatment of PPT may be justified on the grounds that it is relatively common and causes considerable postpartum morbidity. Large-scale intervention trials are urgently needed to assess the efficacy of preconception or early pregnancy screening for thyroid disorders.

Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this article, the reader should be able to state that thyroid gland physiology changes with pregnancy, recall that levels of thyroid hormones are gestational-age related, and explain that accurate interpretation of both antepartum and postpartum levels of thyroid hormones are important in preventing pregnancy-related complication secondary to thyroid dysfunction and in the diagnosis and management of postpartum thyroiditis.