Generally speaking, there are two main factors that cause cleft lip and palate, one is genetic factor and the other is environmental factor. Genetic factors are mostly genetic, and the same symptoms often exist in the immediate or collateral relatives of infants with cleft lip and palate. Among the factors inducing cleft lip and palate, environmental factors are more complicated, which refers to the growth and development environment of embryos. For example, during pregnancy, pregnant women may frequently vomit or have a partial eclipse, resulting in the lack of vitamins A, B, calcium, iron, phosphorus and folic acid; For another example, pregnant women are stimulated during pregnancy and have excessive mental stress; Or get sick during pregnancy, especially suffering from viral cold, rubella and so on. Taking some drugs, such as cortisone or sleeping pills, at the 7th ~12nd week after pregnancy may lead to the mutation of embryonic cells, causing cleft lip and palate symptoms.