What causes a cleft lip or palate during pregnancy?

Cleft lips and palates usually occur very early in fetal development. It happens when there is not enough tissue to join together or if the tissues simply do not join together correctly, reports WebMD. Cleft palate occurs in about one out of every 700 births.

A cleft lip can be corrected with surgery and is usually completed by the time the baby is three months old, according to WebMD. On the other hand, a cleft palate requires multiple surgeries over a period of time, with the first surgery occurring before the baby turns a year old. Some children may need a bone graft to help fill in the cleft palate.