Thyroid Regulation and Dysfunction in the Pregnant Patient

Thyroid disease in pregnancy is a common clinical problem. During the past 2 years significant clinical and scientific advances have occurred in the field. This chapter reviews the physiology of thyroid and pregnancy focusing on iodine requirements and advances in placental function. There follows discussion on thyroid function tests in pregnancy and their interpretation noting ethnic variation in pregnancy range. Sections on iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy, thyrotoxicosis in pregnancy, thyroid nodules and cancer in pregnant women, fetal and neonatal considerations, thyroid disease and lactation, screening for thyroid dysfunction in pregnancy will inform the reader of the current information on these areas. Postpartum thyroid disease is also discussed. Current topical fields of importance include the role of isolated hypothyroxinemia on obstetric outcomes and neurodevelopment, the influence of thyroid autoantibodies on the same parameters and the effect of recent data on malformations associated with antithyroid drug therapy on management guidelines for thyrotoxicosis in pregnancy. It also seems as if pregnancy may have a deleterious effect on the progression differentiated thyroid cancer in pregnancy; this requires more confirmation. The intense debate on whether to screen for thyroid function in all pregnant women continues. Although the few randomised trials which have been performed are negative several areas of the world and some clinics in USA recommend screening. In general recent guidelines from USA and Europe find no evidence to support routine screening.