What is the prevalence of unilateral cleft lip?

Unilateral cleft lip, also known as unilateral cleft lip with or without cleft palate, is a birth defect that occurs when there is a failure of the lip to fuse completely on one side. It is the most common type of cleft lip, accounting for approximately 45% of all cleft lip cases. Unilateral cleft lip affects approximately 1 in 1,000 live births worldwide, with a slightly higher prevalence in males than in females.