Exploring the Science of Cleft Lip and Palate

One in 700 children are born with the birth defect each year. Here’s what you need to know about how clefts form, what causes them and how they can be repaired.

By Alex Orlando
Nov 15, 2021 4:00 PMJul 25, 2022 3:23 PM
cleft lip and palate
(Credit: malost/Shutterstock)


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When I was born, two tiny gaps (no more than a few millimeters across) split apart my upper lip and the roof of my mouth. My parents had known about this craniofacial anomaly — immediately apparent to anyone who saw me — at least several weeks before my birth thanks to a routine ultrasound. Over the course of the next few decades, I would undergo countless surgeries, from complicated orthodontic procedures to (literally) jaw-breaking bone grafts.

My experience is hardly unique. One in 700 babies are born with either (or both) a cleft lip and cleft palate, which occurs when the lip or mouth doesn’t properly fuse during early pregnancy. “Cleft lip and palate is one of the most common congenital birth defects,” says Janice Lee, clinical director for the National Institute of Dental and Craniofacial Research. “It’s a separation in the lip and nose, and in the palate. […] And there’s a gap between the mouth and the nose.”

This seemingly small gap can cause big problems. For starters, says Lee, it can pose issues with feeding, as babies born with clefts aren’t able to form a seal with their mouths. Speech difficulties can also arise, since the palate is crucial in forming certain sounds. (Oddly enough, chronic ear infections and hearing problems are also common, since any malformation in our upper airways can cause fluid to build up in the middle ear.) And some may struggle with stigmatization from others, particularly in lower-resource countries where surgery isn't always an option, due to such a visible facial difference.  

Still, despite their prevalence, there’s plenty that people don’t know about clefts. “A lot of people don’t know how common they are,” says Brent Collett, a behavioral psychiatrist at Seattle Children’s Research Institute who studies young children with craniofacial conditions. “There are a lot of babies who are affected by this.”

What Causes a Cleft?

During the early stages of pregnancy — when an embryo is no larger than a grain of rice — both body tissue and specialized cells from each side of the head grow towards the center until they join together. “Facial development occurs at six weeks in utero,” says Lee. This fusion forms our facial features, like the lips, nose and mouth. (In this sense, everyone starts out with a cleft lip and palate.) But when those tissues don’t fuse, it can result in a cleft lip, when the upper lip doesn’t form properly, and/or cleft palate, when the roof of the mouth doesn’t close.

Clefts have likely been around for a long time; just look at King Tut, who suffered from a partial cleft palate. Throughout history, many have tried to suss out what, exactly, causes their occurrence. One theory posited that if a pregnant woman was carrying a sharp object during an eclipse, her infant could be born with a cleft. A similarly superstitious notion crops up in Shakespeare’s A Midsummer Night’s Dream, where mischievous fairies are responsible for clefts alongside other physical blemishes. A more mechanistic explanation emerged in the eighteenth century, when physicians speculated that abnormal pressures from the jaw and tongue could keep the palate from closing. Even today, some cultures view the condition as divine punishment for parental sins.

But scientists still don’t know precisely what causes most clefts. Most researchers believe that they’re caused by a cocktail of genetic and environmental factors. “It’s a complex, multi-factorial condition, meaning a lot of things can cause it,” says Lee, who adds that scientists are continuously identifying new genes that seem to be associated with it. In 2019 study published in Science Advances, researchers from the University of Pennsylvania’s Perelman School of Medicine identified more than 100 new genes that could lead to the development of cleft lip and palate.

Environmental factors likely play a role, too. Scientists know that smoking, diabetes and certain medicines used to treat epilepsy can boost a parent’s risk of having a baby with a cleft. There’s also evidence to suggest that taking folic acid supplements can grant additional protection. “Folic acid is really important for in-utero development,” says Lee. “It’s really important for moms to know, as soon as they recognize that they’re pregnant. Moms are constantly encouraged to maintain their nutrition and take these vitamins.”  

Still, there are no definitive measures that parents can take to ensure that their child won’t be born with a facial cleft — and if they are, it’s no cause for self-blame. “For moms in particular, they might be concerned that they did something during or before pregnancy to cause this to happen,” says Collett. Beyond that, he continues, parents may have concerns about their child’s development, or how they might be treated by others. Fortunately, for many in the U.S. and other countries, there is a clear path to treatment.

Closing the Gap

There’s no “one-size-fits-all” approach when it comes to repairing clefts. Still, Lee says that in the U.S., the surgical trajectory is pretty consistent. “Most babies will have their cleft lip repaired first, and that allows them to [make a] seal properly, and that continues before the baby is 6 months old” she says. “And then the baby will undergo cleft palate repair, usually around a year old; as the baby starts to babble, you want them to have that seal in the palate so there isn’t air escaping between the palate and the nose.” As the child grows, they’ll typically undergo a series of orthodontic treatments, and may need additional surgeries, as well. Some adults born with a cleft have had more than 20 operations on their mouth, nose and jaw throughout their life.  

These years of intensive procedures add up — the total lifetime treatment cost can exceed $200,000 per person. Plus, beyond the needs of surgical care, individuals with clefts may also have an increased risk for certain diseases like breast and lung cancer, and tend to experience more learning difficulties as young children. “There’s some evidence that kids with clefts may be more inhibited [in classroom settings],” says Collett. “It’s really hard to know if that might be about having a history of stigmatization and not wanting to put themselves out in the forefront, but that is one finding that comes up a fair amount.”

Even when facing these hurdles, with treatment, most children with clefts are able to lead happy and healthy lives. “Having a congenital birth defect really doesn’t define you,” says Lee. “That’s so important for families to know and feel; there are teams that want to support the whole family. And we hope that there are non-invasive therapies in the future so that kids don’t have to go through multiple surgeries.”

For cleft patients that have had scores of surgeries throughout their life, it’s important to remember that each treatment represents another step in a longer journey. Last November, at the age of 31, I was delighted to get new prosthetic front teeth after a significant surgical repair the previous summer. Before, like many with clefts, I sometimes smiled without showing my teeth. Now, I’m much more likely to flash a toothy grin whenever someone pulls out a camera.

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