A to Z: Cleft Lip, Unilateral

A unilateral cleft lip is a common birth defect in which a baby's lip doesn't form properly, resulting in a split (cleft) on one side of the lip.

More to Know

A unilateral cleft lip may appear as a small notch in the edge of the lip only or extend into the nose or gums. A child may be born with just a cleft lip or may have a cleft palate as well, which is a split in the roof of the mouth.

Sometimes a cleft occurs as part of a syndrome, meaning there are other birth defects. Other times, it's genetic and runs in families. A cleft also can be associated with environmental factors, such as a woman's use of certain medications, exposure to cigarette smoke, or lack of certain vitamins while pregnant. Most of the time, though, the cause isn't known.

Cleft lip can be associated with other problems, including feeding difficulties, fluid buildup in the middle ear and hearing loss, dental abnormalities, and speech difficulties.

Keep in Mind

The good news is that cleft lip is treatable. Most babies born with cleft lip can have surgery to repair the defect between the ages of 3 to 6 months, and will go on to lead normal, healthy lives. They may, however, need to have additional surgeries as they grow older.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.