A cleft palate is a birth defect that occurs when the tissue in the roof of the mouth does not fuse together completely during development in the womb. This results in an opening or split in the roof of the mouth, which can be in the back of the palate (the soft palate) or extend into the front of the palate behind the gums (the hard palate) . Cleft lip and cleft palate are among the most common birth defects. Some babies may have only a cleft palate, only a cleft lip, or both.

The lip forms between the fourth and seventh weeks of pregnancy, and the palate is formed between the sixth and ninth weeks of 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 if the tissue that makes up the roof of the mouth does not join together completely during pregnancy. For some babies, both the front and back parts of the palate are open, while for others, only part of the palate is open.

Cleft lip and cleft palate occur when tissues in the babys face and mouth do not fuse properly. Normally, the tissues that make up the lip and palate fuse together in the second and third months of pregnancy. But in babies with cleft lip and cleft palate, the fusion never takes place or occurs only part way, leaving an opening (cleft) . The causes of orofacial clefts among most infants are unknown, but some children have a cleft lip or cleft palate because of changes in their genes. Cleft lip and cleft palate are thought to be caused by a combination of genes and other factors, such as things the mother comes in contact with in her environment, or what the mother eats or drinks, or certain medications she uses during pregnancy.

Cleft palate can cause several problems, including difficulty with feeding, ear infections, dental problems, and speech problems. However, most of these problems can be improved after surgery and with treatments such as speech and language therapy.