A bilateral cleft lip is a common birth defect in which a baby's lip doesn't form properly, resulting in splits (clefts) on both sides of the lip.
A bilateral cleft lip may appear as small notches in the edges 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.