Did you know that your baby’s genetic makeup was determined at conception? From the moment the sperm met the egg, your little one’s genetic code — DNA — began forming. It’s made up of 23 pairs of chromosomes. Sometimes, though, extra chromosomes make their way into the mix and can result in something called a trisomy.

Edwards syndrome is also known as trisomy 18. It means a person has an extra copy of chromosome number 18, leading to issues with development. Here’s more about the symptoms of this syndrome, what causes it, and what you might expect after a diagnosis.

Trisomy 18 is a rare genetic disorder that affects approximately 1 in every 3,315 births in the United States — around 1,187 babies each year.

In typical development, a baby gets 23 pairs of chromosomes from its parents during conception — 22 are called autosomes, and 1 set is made up of sex chromosomes (X and/or Y, depending on the baby’s sex).

The word “trisomy” means three bodies. When there are three copies of the chromosome versus the usual two, it creates an imbalance. As a result, a baby may be born with certain structural changes some of which may lead to miscarriage, stillbirth, or death after the baby is born.


Babies can be born with an extra copy of chromosome 18 in each cell in the body. This is called complete trisomy 18 and causes more serious health outcomes.

Mosaic trisomy 18 happens when only some cells in the body contain the extra chromosome. Around 5 percent of babies with trisomy 18 have the mosaic form. This generally leads to milder irregularities and longer life expectancy.

Partial trisomy 18 happens when an extra copy of chromosome 18 attaches to another chromosome. Again, the severity of the syndrome tends to be associated with the total number of cells affected by the trisomy. So, a partial trisomy tends to have less severe effects and longer life expectancy.

You may not notice anything different in your pregnancy if your baby has Edwards syndrome. In fact, you may not learn about your baby’s diagnosis until after your doctor orders certain prenatal screening tests, like:

Some families do not discover their child’s diagnosis until birth, when the following physical features may include:

Other health issues may include:

  • feeding or sucking difficulties
  • trouble gaining weight (also known as failure to thrive)
  • congenital heart issues, like ventricular septal defect
  • cryptorchidism — undescended testicles
  • eye or vision issues, like clouding of the corneas, small eyes, strabismus (crossed eyes), or nystagmus (uncontrolled eye movements)
  • hearing loss
  • seizures
  • gastrointestinal issues
  • cancerous tumors, particularly in the kidneys and liver

Trisomy 18 is caused by any situation that leads to an extra copy of chromosome 18 in the body.

In most cases, it happens when the sperm meets the egg during conception. In one scenario, the reproductive material of either parent may spontaneously divide. In another, the trisomy may happen as cells divide after fertilization. Whatever the case, the extra chromosome happens at random.

Translocation is another possibility, which means that parts of chromosomes break off and attach to other chromosomes. This may happen randomly or through a “balanced” translocation, in which one parent has a set of chromosomes that aren’t typical but are balanced. When chromosomes are balanced, they don’t cause medical issues. After reproduction, though, genetic information passed on may cause a trisomy.

Edwards syndrome may be diagnosed at some point during your pregnancy. You may have a cell-free DNA screening (cfDNA) at any time after 10 weeks of pregnancy and until delivery. cfDNA is a simple blood test that screens for genetic conditions. A positive result on this test means you’ll need further testing to confirm the results.

Other tests during pregnancy include:

  • Amniocentesis and chorionic villus sampling are more invasive diagnostic tools you may get after 15 weeks of pregnancy. Your doctor will take a sample of your amniotic fluid or placenta to look for extra copies of chromosome 18.
  • An ultrasound exam may uncover physical features (small head, webbed neck, hand or foot irregularities, etc.) of the syndrome.

Other times, trisomy 18 may not be diagnosed until after your baby is born. Your child’s doctor may diagnose it based on:

  • physical features or characteristics
  • heart issues or other defects
  • blood tests that analyze your child’s chromosomes

Questions for your doctor or healthcare professional

If you have recently learned your baby may have trisomy 18, you likely have many questions.

Some questions you may want to ask your doctor include:

  • What, if any, additional testing or monitoring do I need?
  • What specialists might I need to see throughout my pregnancy?
  • What options are available to us depending on how the pregnancy progresses?
  • Are there any local resources or support available for families of children with trisomy 18?

After birth, you may have additional questions:

  • Does my child have a complete, mosaic, or partial trisomy?
  • What treatments may help my baby after birth?
  • What therapies may help my baby as it grows?
  • What help is available for my child’s feeding issues?
  • What other specialists should be part of my child’s medical team?
  • Should my partner and I seek genetic testing before having more children?
  • How do palliative and hospice care differ from traditional medical care?
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There is no cure for trisomy 18. Since babies with this condition tend to have multiple health issues, you’ll work with a team of doctors to create a customized treatment plan. In more severe cases, some families favor palliative care or hospice care.

Treatments are more about making a child comfortable or correcting the issues that affect an individual child. For example, surgery may be an option to treat things like:

  • heart defects
  • kidney issues
  • head or face irregularities

As a child grows, they may need support academically and physically. Early intervention and special education programs can help fill these gaps.

You may be surprised to learn that there are very few risk factors for Edwards syndrome.

There may be an increased chance of having a baby with a trisomy as you get older. While different reports show mothers in their late teens and 20s can have children with trisomy 18, the mean age is closer to 32.5 years old.

In rare cases, trisomy 18 may be inherited from a biological parent (through balanced translocation). If you already have had one child with a trisomy, your doctor may suggest getting genetic testing to assess your chances of having another child with a similar condition.

The vast majority of the time, though, Edwards syndrome happens by chance during conception when the sperm meets the egg.

It’s important to be prepared for all possibilities with a condition like trisomy 18. Researchers share that nearly half of all babies born with Edwards syndrome who survive delivery may not live beyond the first week of life.

That said, the severity of the syndrome depends on the type (complete, mosaic, partial, etc.) and whatever effects it has on your individual child. All children are different, and all outlooks will be unique as a result.

Of children born with Edwards syndrome, nearly 50 percent will not survive beyond the first week of life. However, around 10 percent will reach their first birthday, and some may live to their teen years or even adulthood, but they will need medical support or therapies, including:

  • physical therapy
  • occupational therapy
  • speech therapy

The medical team that may treat a child with trisomy 18

Various doctors and healthcare professionals may need to be a part of your team. Medical issues and their severity are different from case to case, child to child. Some members of the medical team may include:

  • Maternal-fetal medicine specialist. A maternal-fetal medicine specialist monitors the pregnant parent and baby during pregnancy.
  • Neonatologists. These doctors treat newborns in the neonatal intensive care unit (NICU) who have complex medical conditions.
  • Pediatric cardiologists. These doctors treat heart conditions in babies and children.
  • Pediatric oncologist. These doctors treat cancers in babies and children.
  • Geneticists. These doctors offer treatment and evaluation of genetic conditions.
  • Pediatric neurologists and neurosurgeons. Pediatric neurologists and neurosurgeons are doctors who treat conditions related to the brain in babies and children.
  • Pediatric ophthalmologists. Pediatric ophthalmologists treat conditions related to the eyes in babies and children.
  • Plastic surgeons. Plastic surgeons treat craniofacial issues (cleft lip and palate) and similar conditions.
  • Additional support professionals. Physical, occupational, or speech therapists support development in a number of ways, whether privately or through public programs.
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While you may be worried about your child and the outlook over the long term, try taking it day by day. And don’t forget about yourself or your own mental health in the process.

There is support for families with children who have Edwards syndrome. Consider contacting the Trisomy 18 Foundation or the Support Organization for Trisomy 13, 18, and Related Disorders (SOFT). Your doctor may also be able to help connect you with a local group for support and other resources.