Congenital hypothyroidism, or primary hypothyroidism, is also called cretinism or cretinism because it begins in the fetus and newborn. The term cretinism suggests that patients with this disease have primarily abnormal intellectual development, accompanied by short stature. The term congenital means that there are congenital factors that lead to primary hypothyroidism, including the following: 1) abnormal development of the thyroid gland, such as congenital absence of the thyroid gland or ectopic thyroid gland; 2) impaired synthesis of thyroid hormones; 3) excessive use of iodine-containing substances or anti-thyroid drugs during pregnancy; 4) autoimmune abnormalities of the thyroid gland or chromosomal aberrations, and rubella in the fetus. All of the above factors can affect the synthesis of thyroid hormones. In order to prevent cretinism, the state now requires early measurement of heel blood in newborns, i.e. 72 hours after birth, to detect congenital hypothyroidism early by measuring TSH. Moreover, this disease, if detected and treated early, can prevent abnormal development of intelligence or stature in the future.