Hypothyroidism is described as abnormally low activity of the thyroid gland, resulting in retardation of growth and mental development in children and adults. It is the most prevalent thyroid disorder. It can lead to a diverse amount of changes in women's menstrual periods, decrease their chances of conceiving, and affect both the course of pregnancy and the neuropsychological development of babies. Throughout pregnancy, there is a considerably increased requirement of thyroid hormones and a substantial risk that a previously unnoticed, subclinical or latent hypothyroidism will develop into overt hypothyroidism. The thyroid inflammation because of patient's own immune system may shape autoimmune thyroiditis (Hashimoto's thyroiditis). Congenital hypothyroidism (CH) happens in approximately 1:2,000 to 1:4,000 newborns. Almost all of the developed countries of the world presently exercise newborn screening to diagnose and cure congenital hypothyroidism in the first weeks of life. This book includes various crucial specifications and innovations for endocrine practice.