Cleft lip and palate are birth defects that occur because a baby’s lip or palate does not fuse properly during pregnancy.

A cleft lip is an upper lip that is split. It is caused by the failure of the tissue of the lip to join before birth during the fourth to the seventh week of pregnancy. The cause of orofacial clefts is usually unknown, however, the combination of genetic and other risk factors, such as hormonal imbalances, nutritional deficiencies and certain medications taken during pregnancy may be causes.1

A cleft palate occurs when the tissue that makes up the roof of the mouth does not join together during the sixth to the ninth week of pregnancy. A baby’s palate may not be fused in the midline of the entire palate or just part of the palate. A cleft palate is a more serious condition than a cleft lip, although both require surgery in order to be corrected.

Other risk factors that increase the chance of a baby having an orofacial cleft are smoking, diabetes, and use of certain medications to treat epilepsy during the first trimester of pregnancy.

Oral issues that occur as a result of a cleft lip or palate can affect both baby and adult teeth including the positioning, size, shape, and number of teeth. Clefts usually occur between the cuspid and lateral incisors.

1 http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002267/