This book is a practical, evidence-based resource covering thyroid disease and its effects on reproduction and fertility, discussing thyroid function and dysfunction – hypothyroidism and hyperthyroidism, thyroid nodules and cancer – during pregnancy as well as its effects on the fetus. It begins with a review of the anatomy and function of the thyroid and the biosynthesis and physiology of thyroid hormones, as well as the pathophysiology of thyroid dysfunction. The chapters that follow discuss thyroid function and dysfunction (e.g., hypothyroidism and hyperthyroidism) during pregnancy and its effects on fertility as well as the developing fetus. The management of thyroid nodules and cancer, the role of thyroid dysfunction in infertility, the role of thyroid autoimmunity and miscarriage, and postpartum thyroiditis are presented in detail in the concluding chapters. Clinical cases and outcomes bookend each chapter, demonstrating current management strategies for a well-rounded presentation.