The thyroid hormone is responsible for metabolism and metamorphosis. Iodine is an element of the thyroid hormone, the deficiency of which leads to hypothyroidism. This happens because iodine is needed for the production of the hormone thyroxine. Hypothyroidism during pregnancy causes defective development and maturation of the growing baby leading to stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf-mutism, etc. In adult women, hypothyroidism may cause menstrual cycle to become irregular.