Edwards’ Syndrome (Trisomy 18)

Edwards’ syndrome, also called trisomy 18, is a rare genetic condition. It’s usually diagnosed during pregnancy or soon after a baby is born.

Symptoms of Edwards’ Syndrome

Babies with Edwards’ syndrome may have some or all of the following signs:

• Low birth weight

• Ears set lower on the head

• Cleft lip or palate

• Clubfoot or clenched fists

• Heart, kidney, or spine problems

• Breathing or feeding difficulties

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Causes

Edwards’ syndrome is caused by having an extra copy of chromosome 18 in the body’s cells. Normally, people have two copies of each chromosome, but with trisomy 18, there are three copies of chromosome 18.

This happens by chance and is not related to anything the parents did before or during pregnancy. The risk of having a baby with Edwards’ syndrome increases with maternal age, and there is a slightly higher risk if a parent has had a previous pregnancy affected by the condition.

Diagnosis and Screening

Edwards’ syndrome can be detected during pregnancy or after birth.

Screening is offered to check the likelihood of your baby having Edwards’ syndrome:

Combined test (10–14 weeks): a blood test and ultrasound scan (often called the 12-week scan).

Quadruple test (14–20 weeks): offered if the combined test wasn’t done.

If screening results suggest a higher risk, you may be referred to a specialist and offered further tests, such as:

• Non-invasive prenatal testing (NIPT)

• Amniocentesis

• Chorionic villus sampling (CVS)

• Amniocentesis and CVS can confirm whether your baby definitely has Edwards’ syndrome and help you understand what this might mean. It’s always your choice whether to have these tests — talk to your midwife or doctor for advice and support.

After birth, additional tests can confirm the diagnosis and identify the specific type of Edwards’ syndrome.

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Types of Edwards’ Syndrome

There are three main types of trisomy 18:

Full trisomy 18 – the most common and severe type, where every cell has an extra chromosome 18.

Mosaic trisomy 18 – only some cells have the extra chromosome; symptoms are often milder.

Partial trisomy 18 – only part of chromosome 18 is extra; this is very rare and may cause fewer symptoms.

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Living with Edwards’ Syndrome

• The condition affects everyone differently.

• Most babies with full trisomy 18 sadly pass away before or shortly after birth.

• Babies with mosaic or partial trisomy 18 may have fewer health problems, and some live into childhood or adulthood.

• All individuals with Edwards’ syndrome will have some level of learning disability and ongoing health needs. Some may develop independence and be able to work or take part in everyday activities, while others will need more regular care and support.