Cleft Lip and Palate (Once Called "Harelip"): Causes and Treatment

"Harelip" is an old word for a cleft lip: an opening in the upper lip that is present at birth because the tissue did not join completely during pregnancy. The word is now considered outdated and offensive, and the correct terms are cleft lip and cleft palate.

This guide explains what a cleft lip and a cleft palate are, what is known about the causes, how common they are and how they are treated. It is general information drawn from public health bodies such as the US Centers for Disease Control and Prevention (CDC) and the UK National Health Service (NHS). It is not medical advice; a child's own doctors and cleft team are the right people to ask about an individual case.

Why "harelip" is no longer used

The old name compared the shape of a cleft lip to the split upper lip of a hare. Many people born with a cleft, and their families, find the comparison hurtful. A 2022 article in the journal BMJ Global Health describes "harelip" as a derogatory term that can add to the stigma around the condition, and notes that cleft organizations advise against using it unless a person with a cleft chooses it for themselves.

Doctors, health services and charities now say cleft lip, cleft palate, or cleft lip and palate. People still search for the old word because they heard it from an older relative or read it in an old book, which is why it appears in the title of this page. The rest of this article uses the correct terms.

What are cleft lip and cleft palate?

A cleft is a gap. According to the CDC, a cleft lip happens when the tissue that makes up the upper lip does not join completely before birth, leaving an opening. It can be a small notch or a wider gap that reaches up toward the nose, and it can be on one side or both.

A cleft palate happens when the tissue that forms the roof of the mouth does not join completely. The opening can affect the front of the palate, the back, or both.

The two develop early in pregnancy. The CDC says the lip forms between the fourth and seventh weeks and the palate between the sixth and ninth weeks. A baby can have a cleft lip alone, a cleft palate alone, or both together.

Cleft lip and palate causes: what is known

For most babies, the exact cause is not known. The CDC states that the causes of clefts among most infants are unknown, and that they are thought to result from a mix of genes and other factors. A cleft is not caused by something a parent did on a particular day, and in most cases it could not have been predicted.

Research has identified some things that raise the chance of a cleft. They are risk factors, not certain causes; most babies exposed to them are born without a cleft, and many babies with a cleft had none of them. The CDC and the NHS list:

• Genes passed on from the parents. The NHS says that if a parent or an earlier child has a cleft, the chance for another child is around 2 to 8%.
• Smoking during pregnancy.
• Diabetes diagnosed before pregnancy.
• Certain medicines taken in early pregnancy, such as some anti-seizure (epilepsy) medicines.
• Drinking alcohol during pregnancy, obesity during pregnancy, and a lack of folic acid, which the NHS also lists.
• Some genetic syndromes. The US National Institute of Dental and Craniofacial Research (NIDCR) notes that clefts can occur as part of more than 400 syndromes.

How common are cleft lip and palate?

They are among the most common differences present at birth. In the United States, the CDC estimates that about 1 in every 1,031 babies is born with a cleft lip, with or without a cleft palate, and about 1 in every 1,563 babies is born with a cleft palate alone.

A cleft lip is often seen on a routine ultrasound scan during pregnancy. A cleft palate on its own is harder to see on a scan and is usually found when the baby is examined after birth.

What problems can a cleft cause?

A cleft is more than a matter of appearance. The NHS lists the main difficulties a baby or child may have before and during treatment:

• Feeding. A baby with a cleft may not be able to form a good seal with the mouth, so breastfeeding or bottle feeding can be difficult without specialist support.
• Hearing. Children with a cleft palate are more likely to get ear infections and a build-up of fluid in the ear, which can affect hearing.
• Teeth. A cleft can mean teeth do not develop in the usual way, and tooth decay is more likely.
• Speech. If a cleft palate is not repaired, speech can be unclear or sound nasal later in childhood.

How are cleft lip and palate treated, and when?

Clefts are treated with surgery, followed by years of support as the child grows. The timing below is what health authorities describe as usual; the plan for any one child is set by their own team.

Lip repair comes first. The NHS says it is usually done when a baby is 3 to 6 months old, and the CDC recommends it within the first 12 months of life. Palate repair usually follows at 6 to 12 months according to the NHS; the CDC recommends it within the first 18 months, or earlier if possible.

Surgery is only part of the care. The NIDCR describes a cleft team that can include plastic and oral surgeons, an ear, nose and throat specialist, a speech pathologist, an audiologist, a pediatric dentist and orthodontist, a pediatrician, a nutritionist and a psychologist or social worker. Many children need feeding support as babies, hearing checks, speech therapy and dental or orthodontic treatment, and some have further operations as they grow.

The outlook is good where this care is available. In the words of the NHS, the majority of children treated for a cleft lip or palate grow up to have completely normal lives.

Cleft care where hospitals are barely working

Everything above depends on a working health system: a safe operating room, anesthesia, nurses who can teach feeding, and follow-up over many years. In Gaza, that system is badly damaged. On 24 September 2026 the World Health Organization said only 19 of Gaza's 36 hospitals were functioning even partially, and none fully. UNICEF's report for the first half of 2026 says more than 18,500 patients, including some 4,000 children, need medical evacuation for care that is not available inside Gaza.

When hospitals have to put emergencies first, planned operations for children, including the kind of staged surgery a cleft needs, are among the things that wait. Our guides to Gaza's hospitals and medical evacuations from Gaza explain the current picture, and a related article covers pediatric neurosurgery and other children's surgical specialties.

Fight for Palestine does not perform surgery or run hospitals. We raise funds for emergency aid delivered through local partner teams, including medical aid. You can read about it on our medical aid campaign page.