what causes cleft lip

Cleft lip and cleft palate are birth defects that occur when a babys lip or mouth do not form properly during pregnancy. A cleft lip happens if the tissue that makes up the lip does not join completely before birth, resulting in an opening in the upper lip. A cleft palate happens when the structures that form the upper lip or palate fail to join together when a baby is developing in the womb, resulting in a gap or split in the upper lip and/or roof of the mouth. The exact reason why this happens to some babies is often unclear, but researchers believe that most cases of cleft lip and cleft palate are caused by an interaction of genetic and environmental factors. Some children have a cleft lip or cleft palate because of changes in their genes, and parents can pass on genes that cause clefting, either alone or as part of a genetic syndrome that includes a cleft lip or cleft palate as one of its signs. In some cases, babies inherit a gene that makes them more likely to develop a cleft, and then an environmental trigger actually causes the cleft to occur. Other factors that can contribute to the development of a cleft include medication the birthing parent took during pregnancy, smoking, and alcohol use during pregnancy.