Thyroid (dys-)function in normal and disturbed pregnancy

During pregnancy, physiologic changes in maternal thyroid function take place especially due to hormonal as well as metabolic processes. Human chorionic gonadotropin activates the maternal thyroid gland leading to increased thyroid hormone production. A sufficient availability of maternal thyroid hormones is essential for fetal development, especially during the first trimester of pregnancy, when the fetal thyroid gland is not yet functional. Current knowledge of thyroid dysfunction including thyroid autoimmunity, hypothyroidism or hyperthyroidism is summarized with special focus on miscarriage and pregnancy disorders. Therefore, a Medline research as well as an analysis of current guidelines on thyroid function and pregnancy was performed. A study focusing on TSH levels in normal and disturbed pregnancies, the risk of miscarriage in association with thyroid autoantibodies, and (subclinical) hypothyroidism in infertile and fertile women were included. Maternal thyroid dysfunction negatively affects pregnancy outcome. Besides a routine iodine supplementation in pregnant women and treatment of hypo as well as hyperthyroidism, TSH levels should routinely be measured in women during childbearing years and adjusted to concentrations < 2.5 mIU/l in order to optimize maternal health and fetal development.