One in 700 babies are born with a cleft. In the United Kingdom, that’s around 1,200 each year, or three every day.
A ‘cleft’ can be a ‘cleft lip’ (one or two gaps in the upper lip), a ‘cleft palate’ (a gap in the roof of the mouth) or a ‘cleft lip and palate’ together. More about cleft.
This section explains why some people are born with a cleft and some of the different things that can affect someone’s chances of being born with a cleft.
How does a cleft happen?
When a baby is growing in the womb, the different parts of their face and mouth develop separately and then come together.
A cleft lip happens when the structure of the top lip doesn’t come together all the way.
A cleft palate happens when the structure of the roof of the mouth doesn’t come together all the way.
This happens very early on in pregnancy. A cleft lip forms at around 4-7 weeks, and a cleft palate at 7-9 weeks.
A baby can be born with a cleft lip, cleft palate, or a cleft lip and palate together.
What causes cleft lip and palate?
We don’t fully understand what causes cleft lip and palate. There are lots of different factors which we think play a part, including both genetic and environmental influences.
Environmental factors
Some factors in pregnancy, such as certain medications, can slightly increase the chance of a baby being born with a cleft. However, it is extremely unlikely that a baby’s cleft was caused by anything the parents did or did not do during pregnancy. Even the healthiest, best-planned pregnancies can result in a cleft, and this is no one’s fault.
Genetic factors
Genes are the instructions our bodies use to grow and function. They determine many of our traits, like hair and eye colour. We each have about 23,000 genes, arranged on structures called chromosomes. Half come from our mother and half from our father.
Everyone has many small differences in their genes. Most of these are harmless and make us who we are, but some can slightly increase the chance of a cleft developing.
What is an ‘isolated’ cleft?
Most clefts occur on their own (isolated clefts), in children who are otherwise healthy.
These clefts are most often thought to be caused by a combination of small genetic variations and environmental or chance factors. This combination of factors is sometimes termed ‘multifactorial’. This video explains how this works.
It is uncommon for isolated clefts to run in families, though it can happen occasionally. We are likely to understand more about what causes clefts in these families in the future.
When might a cleft be part of a genetic condition?
Less frequently, a cleft may be part of a genetic condition caused by a specific change in the DNA. Doctors may suspect this if:
- Other family members have a cleft, or
- The affected child has additional medical problems or developmental differences.
Research into the causes of cleft
Research continues into the biological and environmental causes of clefts, their treatment, and their emotional impact on families. Our understanding of the genetics of cleft lip and palate continues to grow with time.
The Cleft Collective: Cleft genetics
Cleft Collective: Cleft genetics
What are the chances of my child being born with a cleft?
On average, one in 700 babies are born with a cleft. This means that there’s around a 0.14% chance of a baby being born with a cleft.
There are many different factors which can change how likely someone is to be born with a cleft. If you were born with a cleft, or you already have a child born with a cleft, your chances of having a baby with a cleft will be higher.
If someone in my family has a cleft, what are the chances my next child will too?
The likelihood depends on several things, including:
- How the affected person is related to you.
- The type of cleft they have.
- Whether a genetic cause has been identified.
If you have a child with an isolated cleft, and no known genetic cause, the chance of your next baby having a cleft is around 2 to 4% (or 2 to 4 out of 100).
If you have an isolated cleft yourself, and no known genetic cause, the chance of having a baby with a cleft is around 2 to 3% (or 2 to 3 out of 100).
If a cleft has a specific genetic cause, the chance may be higher or lower than this, depending on the condition. For example, pits (or indents) on the lips can indicate a genetic condition with a higher chance of being passed on to your children.
Is there anything I can do to reduce the chance of a cleft in a future pregnancy?
In most cases, there is nothing specific that the parents did or did not do to cause a cleft. However, all couples planning a pregnancy are advised to follow NHS recommendations. This includes stopping smoking, taking folic acid and maintaining a healthy weight.
If you (or your child) become pregnant in the future, it may be possible to request an additional scan to carefully check the baby’s lip. This is sometimes offered before the standard 20-week scan. This should be discussed with the midwife at the start of the pregnancy.
Cleft Talk: Genetics and decision-making around having children
What is genetic testing?
Genetic testing can be used to find out whether a person is carrying a specific alteration in a gene (known as a genetic variant or ‘mutation’) which can cause or contribute to a particular medical condition such as cleft.
If you have questions about genetics, please speak to your Cleft Team. They may answer your questions or, if needed, refer you to a Clinical Geneticist or Genetic Counsellor.
You may be referred to Clinical Genetics if:
- Your child has a cleft with other medical or developmental concerns.
- You have more than one close relative with a cleft.
- You are planning another pregnancy and want to discuss the chances of a cleft occurring.
- There is a known genetic condition in your family that causes clefts.
You can access genetic counselling at any time. You don’t have to wait until you are planning to have children to see the genetic specialist. Because genetic counselling is part of NHS cleft treatment, it is free of charge.
Even if you don’t have questions now, you or your child may wish to speak to a Clinical Genetics team in the future, for example, when your child grows up and is considering having their own children.
Find details of Regional Clinical Genetics Services
What happens at a Clinical Genetics appointment?
At your appointment, the Clinical Geneticist will:
- Take a detailed family and medical history.
- Examine you or your child (with both their parents, if possible).
- Discuss whether there are any genetic tests they could offer you.
If testing is offered and you decide to go ahead, a small blood sample may be taken. Sometimes this can be arranged to coincide with planned surgery.
Please note: genetic test results can take several months to come back.