A cleft lip is an opening or split in the upper lip that doesn't close fully when an unborn baby is developing in the womb. Cleft lip may happen only on one side (unilateral) or both sides (bilateral). A baby with a cleft lip also may have a cleft in the roof of the mouth called a cleft palate.
Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission.
Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press.
Benefactor support fuels Mayo Clinic’s groundbreaking research. Make a gift today to help us save lives.