The exact causes and pathogenesis of developmental and fusion disorders are not fully understood. According to a large number of experimental research and epidemiological investigation results, it may be caused by many factors rather than a single factor. Generally speaking, it can be divided into genetic factors and environmental factors, which are related to nutrition, heredity, infection, endocrine and other factors.
1. Genetic factors Patients with cleft lip can find similar deformities in their immediate or collateral relatives, so it is considered that cleft lip deformity is related to heredity. Epidemiological investigation shows that the incidence of cleft lip in offspring of relatives with cleft lip deformity is higher than that of relatives without cleft lip deformity. Genetic research also believes that cleft lip is a polygenic genetic disease.
2. Environmental factors mainly refer to the environment of embryo growth and development, and the whole physiological state of the mother constitutes the environmental conditions of embryo development. Therefore, in the first three months of pregnancy, when the maternal physiological state is violated or disturbed, it may affect the growth and development of the embryonic maxillofacial region.
(1) nutritional deficiency in experimental animal studies, it is found that mice will have cleft lip and other deformities when they lack vitamin A, B2, folic acid and other food ingredients, but it is not clear whether humans will also have congenital deformities due to the lack of these substances. Therefore, nutritional deficiency in early pregnancy may be one of the inducing factors.
(2) Infected and injured mothers, if they suffer some kind of damage in the early pregnancy, especially will cause damage to the uterus and its adjacent parts, such as improper incomplete abortion or unscientific drug abortion. , will affect the development of embryos, leading to deformity. Maternal viral diseases such as rubella can also affect the development of embryos and become a possible cause of cleft lip.
(3) Endocrine influence: The baby born after the early pregnancy due to illness and hormone therapy has some congenital malformation. In addition, in the investigation of the family history of children with cleft lip, it is also found that some mothers have various obvious mental trauma factors in the early pregnancy, which may lead to stress reaction, increase the secretion of adrenocortical hormone in the body and induce congenital malformation.
(4) Drug factors Most drugs can enter the embryo through the placenta after entering the mother. Some drugs may affect the development of embryos and cause deformities. At present, the known anti-tumor drugs (such as cyclophosphamide, methotrexate, etc. ), anticonvulsants (phenytoin sodium), histamine drugs and some sleeping pills (such as thalidomide) can all cause fetal malformation.
(5) Pregnant women's frequent exposure to radiation or microwave and other physical injuries during fetal development may affect the growth and development of the fetus and become the possible cause of cleft lip.
(6) Alcohol and tobacco factors Smoking and drinking heavily in the early pregnancy, the incidence of cleft lip in their children is higher than that in women without alcohol and tobacco hobbies, which is also one of the possible factors leading to fetal cleft lip.