If a pregnant woman is a hypothyroid patient and is not actively treated, her child has a higher probability of developing cretinism, and if she is actively treated, the fetus may be normal. Thyroid hormone is a necessary hormone for nerve cell differentiation, proliferation, development and growth. If a pregnant woman is diagnosed with hypothyroidism before pregnancy and is not actively treated, it may lead to impaired development of the fetus. Therefore, a pregnant woman should have a good physical examination before pregnancy as well as a good screening of newborns for hypothyroidism during pregnancy, and the discovery of hypothyroidism should be corrected in a timely manner. It is recommended to do a good pre-pregnancy checkup and body hormone level checkup is necessary to reduce the incidence of cretinism in the child, if the child has signs of cretinism, should go to the hospital in a timely manner to do the appropriate examination and active treatment.