Edwards Syndrome (Trisomy 18)

What is Edwards syndrome (trisomy 18)?

Edwards syndrome, also known as trisomy 18, is a very severe genetic condition that affects how your child’s body develops and grows. Children diagnosed with trisomy 18 have a low birth weight, multiple birth defects and defining physical characteristics.

Who does Edwards syndrome (trisomy 18) affect?

Edwards syndrome (trisomy 18) can affect anyone. The condition occurs when a person has an extra copy of chromosome 18, which is random and unpredictable. The likelihood that a parent will have a child with Edwards syndrome (trisomy 18) increases with maternal age at the time of pregnancy. If a parent had a child with Edwards syndrome (trisomy 18) and becomes pregnant again, it’s unlikely they’ll have another child diagnosed with the same condition (no more than 1%).

How common is Edwards syndrome (trisomy 18)?

Edwards syndrome (trisomy 18) occurs in an estimated 1 out of every 5,000 to 6,000 live births. The condition is more common during pregnancy (1 out of every 2,500 pregnancies), but most (at least 95%) fetuses don’t survive full term due to complications from the diagnosis, so pregnancies can end in miscarriage or babies are stillborn.

When was Edwards syndrome (trisomy 18) discovered?

John Hilton Edwards, et al., discovered Edwards syndrome (trisomy 18) in 1960 after researching a newborn with multiple congenital complications and issues with cognitive development. They reported their discovery and identified the condition as the result of a third cell attaching to a pair of chromosomes at chromosome 18 (trisomy 18).

What are the symptoms of Edwards syndrome (trisomy 18)?

Symptoms of Edwards syndrome (trisomy 18) typically include poor growth before and after birth, multiple birth defects and severe developmental delays or learning problems. Symptoms are present during pregnancy and after your child is born.

Symptoms of Edwards syndrome (trisomy 18) during pregnancy

Your healthcare provider will look for signs of Edwards syndrome (trisomy 18) during a prenatal ultrasound, including:

• Very little fetal activity.
• A single artery in your umbilical cord.
• A small placenta.
• Birth defects.
• Your fetus is surrounded by too much amniotic fluid (polyhydramnios).

An Edwards syndrome diagnosis can result in a live birth, but trisomy 18 most often causes a miscarriage during the first three months of pregnancy or the baby is stillborn.

Characteristics of Edwards syndrome (trisomy 18) after birth

After your baby is born, your child likely has physical characteristics of Edwards syndrome (trisomy 18), including:

• Decreased muscle tone (hypotonia).
• Low-set ears.
• Internal organs forming or functioning differently (heart and lungs).
• Issues with cognitive development (intellectual disabilities), which are typically severe.
• Overlapping fingers and/or clubfeet.
• Small physical size (head, mouth and jaw).
• Weak cry and minimal response to sound.

Severe symptoms of Edwards syndrome (trisomy 18)

Because children diagnosed with Edwards syndrome (trisomy 18) have underdeveloped bodies, the side effects of the condition have serious and often life-threatening consequences, including:

• Congenital heart disease and kidney disease (present at birth).
• Breathing abnormalities (respiratory failure).
• Gastrointestinal tract and abdominal wall issues and birth defects.
• Hernias.
• Scoliosis.

Issues relating to the heart affect nearly 90% of children diagnosed with Edwards syndrome (trisomy 18) and are the leading cause of premature death among infants who have the condition, next to respiratory failure.

What causes Edwards syndrome (trisomy 18)?

Having three copies of chromosome 18 instead of the typical two causes Edwards syndrome (trisomy 18).

All humans have 46 chromosomes that divide into 23 pairs. Chromosomes carry your DNA in cells, which tells your body how to form and function as its instruction manual. You receive one set of chromosomes from each of your parents.

When cells form, they start in reproductive organs as one fertilized cell (sperm in males and eggs in females). Cells divide (meiosis) to create pairs by copying themselves. The cell’s copy contains half the amount of DNA as the original cell, 23 chromosomes from 46, and each chromosome pair has a number.

During egg and sperm formation when chromosome pairs are supposed to divide, there’s a chance that a chromosome pair will not divide (as if they are too sticky) and both copies will be included in the egg or sperm. When fertilization happens, those two copies join one from the other parent so the result is three copies in total. The incorrect number of chromosomes is unpredictable and random and isn’t the result of something the parents did before or during pregnancy.

When a third copy of a cell joins a pair, a trisomy occurs. Trisomy means “three bodies.” If someone receives an Edwards syndrome diagnosis, they have a third copy of chromosome 18 in their cells.

How is Edwards syndrome (trisomy 18) diagnosed?

Diagnosis of Edwards syndrome (trisomy 18) begins during pregnancy, and confirmation of the diagnosis occurs either before or after your baby is born. Your healthcare provider will look for signs of Edwards syndrome (trisomy 18) during a routine ultrasound screening, including fetal activity, the amniotic fluid surrounding your fetus and the size of your placenta. If signs of a genetic condition are present, your healthcare provider may offer additional testing for confirmation.

What tests diagnose Edwards syndrome (trisomy 18)?

During pregnancy, your healthcare provider will offer different tests to determine the diagnosis of your child if they show symptoms of Edwards syndrome (trisomy 18). These tests include:

• Amniocentesis: Between 15 and 20 weeks of pregnancy, your healthcare provider will take a small sample of amniotic fluid to identify potential health conditions in your baby.
• Chorionic villus sampling (CVS): Between 10 and 13 weeks of pregnancy, your healthcare provider will take a small sample of cells from your placenta to look for genetic conditions.
• Screenings: After 10 weeks of pregnancy, your healthcare provider will examine a sample of your blood to assess whether or not your child has common extra chromosome conditions, including trisomy 18.

After your child is born, your healthcare provider will examine your child’s heart via ultrasound to identify and treat any heart-related conditions as a result of their diagnosis.

How is Edwards syndrome (trisomy 18) treated?

Often, the condition is so severe that babies who survive being born are treated with comfort care. But treatment for Edwards syndrome (trisomy 18) is unique for each child, based on the severity of their diagnosis. There’s no cure for Edwards syndrome (trisomy 18).

Treatment for Edwards syndrome (trisomy 18) might include:

• Cardiac treatment: Heart problems affect nearly all cases of Edwards syndrome (trisomy 18). Not all babies with cardiac problems due to Edwards syndrome (trisomy 18) are eligible for surgery, but some might be.
• Assisted feeding: Children diagnosed with Edwards syndrome (trisomy 18) can have problems eating normally due to delayed physical growth. A feeding tube might be necessary to address early feeding problems after your child is born.
• Orthopaedic treatment: Children diagnosed with Edwards syndrome (trisomy 18) may have spinal problems like scoliosis, which could impact how your child moves. Orthopaedic treatment could involve bracing or surgery.
• Psychosocial support: Support is available to you, your family and your child diagnosed with Edwards syndrome (trisomy 18), especially to help cope with the loss of your child or help you navigate your child’s complex diagnosis.

How can I reduce my risk of having a child with Edwards syndrome (trisomy 18)?

Edwards syndrome (trisomy 18) is the result of a genetic mutation and there’s no way to prevent the condition. However, if you qualify for a combination of genetic testing and in vitro fertilization (preimplantation genetic testing), you can significantly reduce the chance of having a child with Edwards syndrome (trisomy 18). If you plan on becoming pregnant and want to understand your risk of having a child with a genetic condition, talk with your healthcare provider about genetic testing.

What can I expect if I have a child with Edwards syndrome (trisomy 18)?

There’s no cure for Edwards syndrome (trisomy 18). Almost all pregnancies end in miscarriage or stillbirth. Of those pregnancies surviving into the third trimester, nearly 40% of babies diagnosed with Edwards syndrome (trisomy 18) don’t survive during labor, and nearly one-third of the surviving babies deliver preterm.

The survival rate varies for babies born with Edwards syndrome (trisomy 18):

• Between 60% and 75% survive to their first week.
• Between 20% and 40% survive to their first month.
• No more than 10% survive past their first year.

Children born with Edwards syndrome (trisomy 18) will need specialized care to address their unique symptoms immediately after they are born. The survival rate is low, especially if your child has delayed organ development or a congenital heart condition. Out of the 10% who survive past their first birthday, children go on to live fulfilling lives with significant support from their family and caretakers, as most never learn to walk or talk.

When should I see my healthcare provider?

One of the side effects of having a child with Edwards syndrome (trisomy 18) is a risk of miscarriage or a loss of pregnancy. If you’re pregnant, contact your healthcare provider if you experience any symptoms of a miscarriage, including:

• Abdominal pain.
• Chills.
• Cramping.
• Heavy bleeding (similar to a heavy period).
• Lower back pain.

When should I go to ER?

If your child born with Edwards syndrome (trisomy 18) has any of the following symptoms, take them to the emergency room or call 911 immediately:

• Breathes quickly or very slowly or not at all.
• Has a blue or purple color to their skin or lips.
• Has a fast heartbeat.
• Has trouble eating.
• Has swelling throughout their body.

What questions should I ask my doctor?

• What are my risks of having a child with a genetic condition?
• What type of treatment is available to target my child’s symptoms?
• What can I do during pregnancy to make sure my baby is healthy?

A note from Cleveland Clinic

An Edwards syndrome (trisomy 18) diagnosis might be overwhelming due to the severe complications that arise from the condition. Your healthcare provider will support you and your family along the journey, helping you navigate your child’s diagnosis or coping with loss. If you plan on becoming pregnant, discuss genetic testing with your healthcare provider to identify your risk of having a child with a genetic condition.