The causes of cleft lip and palate are not yet completely understood, but are generally considered to be related to several factors: 1. Nutritional deficiencies, especially vitamin deficiencies, are now considered to be an important factor in causing cleft lip and palate deformities. A history of malnutrition and vitamin deficiencies (including excessive vomiting) in the first trimester of pregnancy may make the fetus susceptible to cleft lip.
Certain drugs such as reactive stop, aspirin, certain antibiotics and corticosteroids can increase the incidence of fetal malformations.
3.Emotional influence It is believed that at the critical moment of lip and palate development, the physical or emotional tension of pregnant women may cause fetal malformation, which is related to the increased secretion of corticosteroids in the mother, thus inhibiting the development of fibroblasts.
4, viral infection is also considered to be a causative factor. Rubella in early pregnancy often leads to fetal malformation. This was confirmed in the 1940 rubella epidemic in Australia. However, whether it is the rubella virus itself or whether the malformation is due to indirect factors is to be further confirmed.
5, genetic factors The occurrence of cleft lip and palate malformation is often related to genetics. We can find more than one patient with malformations in a family, and the presence of the same malformation in direct or collateral relatives can also be found during consultation of family history. The highest figure in the literature is that Fogh-Anderson reported a 27% heritability of cleft lip and up to 41% of coexisting cleft lip and palate, while the heritability of cleft palate alone is 19%. The statistic of Song Ruyao (1957) was 4,3%. These data vary widely and further statistics are needed. But more important is the result of genetics itself variation. These hereditary properties can change due to the living conditions and metabolic variation, but will never be inherited unchanged to the offspring.
In addition, radiation can also cause fetal malformations. In conclusion, the normal development of the first and second parotid arches is affected by a factor during the fourth to eighth weeks of embryonic development, causing cleft lip, and during the eighth to twelfth weeks, cleft palate may appear.