- Genes. Both mothers and fathers can pass on a gene or genes that cause cleft palate or cleft lip.
- Environmental factors (outside influences). Pregnant women who take certain medicines — such as medicines to control seizures — may be more likely to have a baby with cleft lip or palate. Women who come into contact with certain chemicals when they're pregnant may also have a baby with a cleft.
Not getting the right nutrition during pregnancy may increase a baby's risk of being born with a cleft. That's why it's important for moms to get vitamins like folic acid. Smoking cigarettes and using drugs and alcohol during pregnancy increase the risk that a baby will have birth defects. Moms who drink four or more alcoholic drinks in a row during the first weeks of pregnancy have a higher risk of having a baby with cleft lip or cleft palate.