Cleft Lip

Cleft lip is a birth defect, or “congenital anomaly,” characterized by one or two splits in a baby’s upper lip.

In this guide, we’ll explain why cleft lip happens, what causes it, how it can affect a child and treatment options.

How Does Cleft Lip Happen?

Between the fifth and twelfth weeks of development, an unborn baby’s face is just beginning to form. Around five weeks, what will eventually become a human face is just a round ball of cells. But soon, small patches of cells will start to push outward.

One patch, on top, will eventually become the forehead and nose. Another patch below will become the lower lip and jaw. As these two areas jut outwards, soft tissues between them are growing from either side. Eventually, these two sides will conjoin, coming together in the middle to fuse and create the upper lip.

The groove under your nose, called the “philtrum,” serves as proof of this process. That’s where the two sides met in the middle.

For babies born with a cleft lip, something stopped this process from coming to completion. The sides never came together, leaving a split in the upper lip rather than a continuous surface.

What Causes Cleft Lip?

In specific patients, doctors are rarely able to fully explain an orofacial difference like cleft lip. But researchers universally agree that this congenital anomaly is caused by an interplay between two factors:

  1. Genetic material
  2. Fetal environment


Genes are often called “the blueprint of life,” and you can think of them like a set of instructions. Every cell in your body has the exact same set of these instructions, and they tell each cell which kinds of proteins to produce, when to do it and how many to make.

When the two sides of an upper lip come together, it’s genes that are telling them how to meet in the middle.

We inherit our unique set of genes from our parents: half from mom and half from dad. But to pass our genetic material on to a child, our genes need to be copied first. Sometimes, mistakes occur during the copying process, producing “genetic anomalies.” That’s one potential cause of cleft lip: abnormal genetic instructions.

Another cause may be that one of a parent’s genes already contain a mistake. Copying goes according to plan, it’s just that the plans themselves tell the embryo to produce an inadequate amount of tissue. Without enough tissue, the two sides of the lip won’t meet in the center.

Genetic Syndromes

A genetic “syndrome” is a condition caused by abnormal genes that has more than one defining characteristic.

There are over 300 different syndromes that have orofacial clefts as one of their features.


During pregnancy, what a mother takes in, eats or drinks, is crucial to her unborn child’s development process. Growing babies rely on a mother’s blood for many nutrients, ones they still aren’t able to produce by themselves.

But lying between a mother and her developing baby is the placenta. This large organ takes in both maternal blood and fetal blood, allowing certain molecules and elements to pass from one to the other. And while the placenta is really good at filtering out some toxins, other dangerous chemicals are allowed to pass through the “placental barrier” and enter the child’s blood stream.

Toxic substances like pesticide and mercury slip right through, traveling down the umbilical cord toward the developing fetus. In 2004, the Environmental Working Group studied the umbilical cord blood from ten newborns. The researchers found an average of 200 “industrial chemicals and pollutants” present in each sample, and a total of 287 different chemicals. 180 of those chemicals are known carcinogens.

One theory is that the human reproductive system evolved long before the development of most harmful chemicals. Our bodies just aren’t equipped to recognize, and deal with, these substances.

In any case, the health community is convinced that some of these chemicals contribute to birth defects. Alcohol and cigarettes are well-known examples of teratogens, substances that can harm a fetus’ development.

Which Chemicals Cause Cleft Lip?

Finding out which substances may specifically cause cleft lip is a more difficult task.

Researchers suspect that it’s often a combination of genetic factors and environmental toxins that result in any particular orofacial cleft. Genes may start the process, but they need a little “push” from the outside world.

Below, you’ll find a list of prescription medications that have been linked to orofacial clefts:

  • Vasoactive drugs, which increase or decrease blood pressure, like pseudoephedrine and aspirin
  • Epilepsy drugs, like Depakote and Dilantin. Some researchers believe that it’s actually epilepsy, and not the medications used to treat it, that increase the risk of cleft lip and / or cleft palate.
  • Isotretinoin, marketed as the acne drug Accutane
  • Corticosteroids like hydrocortisone and cortisone

For a detailed look at the association between certain prescription drugs and cleft lip, click here.

Does Cleft Lip Hurt?

No. Orofacial clefts do not cause babies physical pain, nor do facial expressions.

How Common Are Cleft Lips?

While orofacial clefts (ones that affect the lip and / or palate) are the second most common birth defect over all, they’re still relatively rare.

According to the National Institute of Dental & Craniofacial Research, between 2004 and 2006, 4,437 children were born with cleft lips, with or without cleft palate. That estimate came from the birth records of 14 states; there is currently no national system for tracking the incidence of orofacial clefts.

In those 14 states, a total of 4,038,506 live births occured over the span of three years included in the study. Based on those numbers, we can estimate that around 0.1% of children are born with cleft lips.

Types Of Cleft Lip

Children can be born with a unilateral cleft lip, in which only one side of the lip is separated, or a bilateral cleft lip, in which both sides are split.

Bilateral clefts can be either asymmetrical or symmetrical. In the asymmetrical form, one side is split more than the other, extending further towards the nose. Symmetrical means that both sides are cleft about the same.

Children born with bilateral cleft lips often have nasal malformations as well. In this case, the split will extend upwards and separate the nostril’s lower portion. If it does, the cleft is called “complete.” If it doesn’t reach the nose, it’s called “incomplete.”

Clefts can also run the other way, separating the “alveolar ridge.” In embryonic development, “alveolar ridge” is a term given to the cells that will eventually become gums and parts of teeth.

Finally, babies born with cleft lip can also have cleft palates, in which a split runs along the roof of the mouth toward the throat.

To learn more about cleft palate, click here.

Effects & Complications Of A Cleft Lip

Babies born with cleft lip usually go on to live full, healthy lives. Complications of an isolated cleft lip, one without a cleft palate, are primarily aesthetic.

While plastic surgeries can repair a cleft and lend the face a more “normal” appearance, scarring from the procedure is probable. Some children experience pressures, both at school and in the world at-large, as a result, although it is rare that true psychological damage is suffered.

Cleft lip with cleft palate generally entails more serious complications:

Problems With Feeding

A continuous palate serves as a barrier between the mouth and nasal passages above. With a split in this barrier, food and liquids may travel up through the nose, rather than back and down through the throat.

Sucking may be difficult, because the palate serves in part to create a vacuum within the mouth. This vacuum helps draw liquids into the oral cavity, but children with cleft lips have trouble creating a tight “seal” on a nipple.

Many of the muscles of the palate are essential in swallowing so this can be hard, too.

Ear Infections

Cleft palates allow liquid and food to enter a network of tubes that connect the ears and nose to the mouth. Fluids that enter tubes that communicate with the ears can cause infections, and children with cleft palates often suffer from chronic ear infections. Over time, this frequent infection can lead to permanent hearing loss.

In general, children with isolated cleft lips are not at risk for this complication.

Speech & Language

Most human speech sounds rely on a “normal” facial structure. A cleft lip can make it difficult for children to form these sounds, inhibiting the very process of learning a language.

Children with cleft lip and palate often have abnormally nasal voices, as the split in their palates allows air to travel through the nose while they are speaking.

Dental Problems

It’s fairly common for the cleft in a lip to extend through the gums, creating an indentation or complete split there, as well. The upper jaw, or maxilla, can be affected as well. In this case, teeth grow at abnormal angles, while the jaw may not be properly aligned.

How Is A Cleft Lip Treated?

Doctors are now able to diagnose cleft lips based on ultrasound readings, as early as 18 weeks of development. Diagnosing a cleft in the palate is more difficult, since it is concealed within the mouth.

After diagnosis, physicians can perform amniocentisis, a procedure in which amniotic fluid is extracted and tested for evidence of a genetic syndrome. Catching an orofacial cleft early is helpful, because treatment usually requires an extensive team of specialists.

Surgery to repair a cleft lip usually occurs between 6 and 12 weeks after a child is born. It’s a type of plastic surgery, but most insurance companies will cover the cost. If a baby’s nose is affected by the cleft, a form of rhinoplasty may be necessary as well.

We’ve created a guide to common insurance company questions that may help if you’re applying for benefits that relate to a child’s orofacial cleft. You can find it here.

Beyond surgery, children born with a cleft lip usually need ongoing therapies from a range of specialized practitioners, in order to achieve full orofacial function.

To find our complete guide to “Treating Cleft Lip & Palate,” click here.