During pregnancy, when the embryonic jaw bone is in the early stage of development and cell proliferation, any factors that hinder the development and cell proliferation of the embryo may affect the development of the embryo, stopping the growth of the embryo and causing tooth loss, the common causes in the clinic are as follows: 1, genetic factors: there is usually a very obvious family history of missing teeth in both parents or grandparents in the family. 2, metabolic disorders: diseases of maternal pregnancy or metabolic disorders cause defects in the development of milk/permanent teeth. 3, nutritional disorders: nutritional disorders such as calcium, iron, protein deficiency in the mother at the early stage of tooth embryo development. 4, endocrine disorders: maternal endocrine disorders at the early stage of tooth germ development can also lead to congenital tooth loss. 5.Radiological influence: If the tooth embryo is exposed to X-rays at the early stage of development, the teeth on the irradiated side may be missing. 6.Infection factors: some disease-causing microorganisms such as rubella virus, syphilis spirochete infection, etc. 7, hereditary diseases: most of the missing teeth and total tooth loss are often related to hereditary diseases such as hereditary ectodermal hypoplasia, a systemic congenital malformation, lack of sebaceous glands and sweat glands, dry skin, little or no sweat and sparse hair, collapsed nose, partial or total absence of teeth. 8, systemic diseases: systemic systemic diseases such as tuberculosis and rickets cause embryonic destruction or hindered development of teeth, which may also cause congenital missing teeth.