Purpose of review: Thyroid disease is common during pregnancy. There are multiple alterations in maternal thyroid physiology, leading to an increased demand for thyroid hormone during gestation, that have significant implications for both maternal and fetal health. Importantly, pregnant reference ranges must be used for appropriate diagnosis and treatment of maternal hypothyroidism. There is currently broad interest in the maternal and fetal complications of hypothyroidism during pregnancy, with significant debate regarding the nuances of screening, despite universal agreement regarding the need for treatment.
Recent findings: Current literature has provided new evidence demonstrating maternal and fetal complications of hypothyroidism during pregnancy. There is evidence for improved outcomes with appropriate treatment of maternal hypothyroidism.
Summary: Although universal screening for hypothyroidism in pregnancy is currently controversial, it is increasingly apparent that maternal hypothyroidism can significantly affect both maternal and fetal health outcomes. Because of the ease and low risk of treatment, current recommendations emphasize appropriate case recognition and treatment to minimize the risk of unnecessary complications.