Down's syndrome, also known as Down syndromw or trisomy 21, is a genetic condition that typically causes some level of learning disability and certain physical characteristics.

Characteristics of Down's syndrome

Most babies born with Down's syndrome are diagnosed soon after birth and may have:

  • floppiness (hypotonia)
  • eyes that slant upwards and outwards
  • a small mouth with a tounge that may stick out
  • a flat back of the head
  • below-average weight and length at birth
  • their palm may have only one crease across it

Although children with Down's syndrome share some common physical characteristics, they don't all look the same.  A child with Down's will look more like their family members than other children who have the syndrome.

People with Down's syndrome will also have different personalities and abilities.  Everyone born with Down's syndrome will have some degree of learning disability, but this will be different for each person.

Screening for Down's syndrome

Sometimes parents find out their baby has Down's syndrome during pregnancy because of screening tests. All pregnant women are offered screening tests for Down's syndrome.

Screening tests can't tell you for certain if your baby has Down's syndrome, but they can tell you how likely it is.

If screening tests show there's a chance your baby has Down's, more tests can be done during pregnancy to confirm it.

These include:

If these tests show that your baby has Down's syndrome, you and your baby's other parent will be offered counselling so you can talk about the impact of the diagnosis.

You may also be offered an appointment to meet a doctor or other health professional who works with children with Down's syndrome. They can tell you more about the condition and answer any questions you have.

See more about screening for Down's syndrome.

Causes of Down's syndrome

wn's syndrome is usually caused by an extra chromosome in a baby's cells. In most cases, this isn't inherited – it's simply the result of a one-off genetic change in the sperm or egg.

There's a small chance of having a child with Down's syndrome with any pregnancy, but the likelihood increases with the age of the mother.

For example, a woman who is 20 has about a 1 in 1,500 chance of having a baby with Down's, while a woman who is 40 has a 1 in 100 chance.

There's no evidence that anything done before or during pregnancy increases or decreases the chance of having a child with Down's syndrome.

Read more about the causes of Down syndrome.

Living with Down's syndrome

Although there's no "cure" for Down's syndrome, there's support available to help children with the condition lead healthy, fulfilling lives.

This includes:

access to good healthcare – including a range of different specialists
support for your child's development – this may include speech and language therapy, physiotherapy, and home teaching 
support groups – such as the Down's Syndrome Association, who can put you in touch with other families who have a child with Down's syndrome

Lots of people with Down's syndrome are able to leave home, have relationships, work, and lead largely independent lives.

Read more about living with Down's syndrome.

Health problems linked to Down's syndrome

People with Down's syndrome are more likely to have certain health problems, including:

Your child may be checked by a paediatrician more often than other children to pick up problems as early as possible. 

If you have any concerns about your child's health, talk to your GP, health visitor or paediatrician.

Read more about the complications of Down's syndrome.

Down's Syndrome Association

If you would like more information about Down's syndrome, you can visit the Down's Syndrome Association or call their helpline on 0333 121 2300

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Each person with Down's syndrome is affected differently, but most share a number of physical characteristics and developmental problems.

Physical appearance

People with Down's syndrome often have certain physical characteristics. Not everyone will have all of them, but they may include:

  • reduced muscle tone which results in floppiness (hypotonia)
  • a small nose and flat nasal bridge
  • a small mouth with a tongue that may stick out
  • eyes that slant upwards and outwards
  • a flat back of the head
  • a big space between the first and second toe (sandal gap)
  • broad hands with short fingers
  • their palm may have only one crease across it
  • a below average weight and length at birth
But people with Down's syndrome don't all look the same – they also look like their parents and family.

Delayed development

All children with Down's syndrome have some degree of learning disability and delayed development, but this varies widely between individual children.

Children with Down's may be slower to learn skills like sitting, standing, walking, and talking. They will develop these skills eventually, it just takes more time.

Around 1 in every 10 children with Down's also have other conditions, such as autism spectrum disorder (ASD) or attention deficit hyperactivity disorder (ADHD).

Children with Down's syndrome often need more support as they grow up, including extra help at school.

Health problems

There are some conditions more common in people with Down's syndrome.

These include:

  • problems with the heart and bowel
  • difficulties with hearing and vision
  • a higher risk of infections

Read more about the possible complications of Down's syndrome.

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Down's syndrome is a genetic condition that occurs as a result of an extra chromosome (chromosome 21).

Chromosomes explained

Our bodies are made up of cells that contain genes. Genes are grouped in thread-like structures called chromosomes.

These contain detailed genetic instructions for lots of different things, including:

  • how a baby's cells develop
  • their gender
  • their eye colour

Usually, cells contain 46 chromosomes – 23 from the mother and 23 from the father.

In people with Down's syndrome, all or some of the cells in their bodies contain 47 chromosomes instead, as there's an extra copy of chromosome 21. This extra gene causes the characteristics of Down's syndrome.

In most cases, Down's syndrome isn't inherited, it's just the result of a one-off genetic change in the sperm or egg.

What are the chances of having a baby with Down's syndrome?

With every pregnancy, there's a small chance of having a baby who has Down's syndrome.

Some people are more likely to have a child with Down's than others.

The main thing that increases the chance of having a baby with Down's syndrome is the mother's age.

For example, a woman who is:

  • 20 years of age has a 1 in 1,500 chance
  • 30 years of age has a 1 in 800 chance
  • 35 years of age has 1 in 270 chance
  • 40 years of age has a 1 in 100 chance
  • 45 years of age has a 1 in 50 or greater chance

However, babies with Down's syndrome are born to women of all ages.

Your chance of having a child with Down's syndrome is also increased if you previously had a child with Down's. For most people, this chance is still small (around 1 in 100).

There's around a 1 in 2 chance of a child having Down's syndrome if one of his or her parents has the condition.

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Living with

With help and support, most people with Down's syndrome are able to have healthy, active and more independent lives.

New parents

If you've recently found out your baby has Down's syndrome, you may be feeling a whole range of emotions, including fear, joy, sadness, or confusion. There's no right or wrong way to react.

It's important to remember you're not alone in your situation. Thousands of people in the UK have Down's syndrome. There are also lots of people who have experience of supporting and caring for people with the condition.

Lots of new parents find it reassuring to talk to other parents. The Down's Syndrome Association can put you in touch with another family who have a child with Down's.

They can share their experiences with you, offer you advice, and talk through any fears or concerns you may have.

Read more information for new parents on the Down's Syndrome Association website.

Helping your child

Most children with Down's syndrome have difficulty learning new things and take a bit longer to reach developmental milestones, such as walking and talking.

There are various things you can do to help your child with their learning and development.

Things that may be useful include:

  • using play to help your child learn – for example, show them how to play with their toys, and use toys to encourage them to reach, grasp, and move
  • naming and talking about things your child's looking at and is interested in
  • giving your child the opportunity to mix with other children
  • encouraging your child to be as independent as possible from an early age with things like feeding and dressing, getting ready for bed, brushing teeth, and going to the toilet
  • playing games to teach new words – a home visiting teacher or speech and language therapist can give you some ideas

It's important to find a balance between "special" activities and all the normal things families do.

As with all new babies, at times they'll need to fit in with what's going on around them.

Not everything you do with your baby needs to be educational or meaningful. Any fun activity with the family can be beneficial.

Professional support

A number of different professionals experienced in caring for children with Down's syndrome will be able to help you with any difficulties you or your child are having.

For many people this will involve an early intervention programme. This is a special programme that aims to help a child with learning disabilities develop, as well as provide support to the family.

An early intervention programme can include:

  • speech and language therapy – to help with any problems communicating or feeding
  • physiotherapy – to help with any muscle weakness or movement difficulties
  • individual home teaching programmes

You'll be advised about things you can do at home to help your child learn and develop. You'll also be able to find out about your child's condition and meet other families like yours.

You can also call the Down's Syndrome Association helpline on 0333 121 2300 for advice.

Financial support

You may feel you need to give up work or decrease your hours so you can spend more time caring for your child.

If this is the case, it's worth finding out about any benefits you may be entitled to.

Read about financial help for parent carers.

Regular health check-ups

Children and adults with Down's syndrome need regular check-ups to monitor their health.

These check-ups will usually be with a paediatrician (a children's doctor) at first. Your GP may do them as your child gets older.

The health check-ups may involve:

  • hearing and vision tests
  • measuring height and weight
  • blood tests to check for thyroid problems
  • checking for signs of heart problems

If your doctor spots any possible problems, they can refer you to a specialist.

School and your child

Lots of children with Down's syndrome are educated in mainstream nurseries or schools with support.

But individual needs vary, and some parents feel a special school will be most suitable for their child.

It might help to visit some mainstream and special schools in your local area. Talk to the staff about how they would meet your child's special educational needs.

You can also find out more about education on the Down's Syndrome Association website.

Teens with Down's syndrome

Until the age of 18, child health and social care services are responsible for the care of children with long-term health conditions like Down's syndrome.

From 18, it's usually the responsibility of adult services. Between the ages of 16 and 18, your child will start a "transition" to adult services.

For more information, read about transition planning for disabled young people.

Adults with Down's syndrome

Further education and employment

Lots of young adults with Down's syndrome pursue further education, and many go on to work.

Living independently

With help and support, lots of adults with Down's syndrome can lead an active and fairly independent life.

Although it may not be possible to live completely independently, some adults with Down's syndrome leave home and live in their communities with support.

Adults with Down's syndrome often move into property owned and staffed by a housing association. Staff can provide different levels of support depending on the person's particular needs.

If necessary, a social worker may be able to help with finding accommodation. An occupational therapist can offer practical advice to help make independent living easier.

Read more about disability and independent living and supported living services.

Relationships, sex and fertility

Lots of people with Down's syndrome have loving relationships, although they may need some support when it comes to things like contraception.

Men and women with Down's syndrome tend to have lower fertility. This doesn't mean they can't have children, but it does make it more difficult.

Those who decide to have children will usually need specialist guidance and support to help them cope with the demands of a new baby.

If one partner in a couple has Down's syndrome, there's around a 1 in 2 chance of each of their children having Down's syndrome, too.

The risk of miscarriage and premature birth is also higher in women with Down's syndrome.

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Some children with Down's syndrome have very few health problems as a result of their condition.  Others will need extra medical care and attention.

Your child will usually need to be checked by a paediatrician more often than other children to pick up developing problems as early as possible.

If you have any concerns about your child's health, talk to your GP, health visitor, or paediatrician.

Heart defects

Around half of children with Down's syndrome are born with a congenital heart defect.

The most common defect to affect children with Down's is a septal defect. This is a hole inside one of the walls that separate the four chambers of the heart, often referred to as a "hole in the heart".

If your baby is diagnosed with Down's syndrome, their heart will be carefully checked to spot any problems as soon as possible. They may need surgery to repair the heart if a problem is found.

Gut problems

Lots of people with Down's syndrome have some sort of problem with their digestive system. Constipation, diarrhoea and indigestion are all more common.

More serious problems may include:

  • small bowel obstruction, which stops food passing from the stomach into the large bowel
  • coeliac disease – a condition where a person has an adverse reaction to gluten
  • reflux – bringing up milk during or shortly after feeding
  • imperforate anus – where a baby is born without an anal opening
  • Hirschsprung's disease – where the bowel is unable to push poo along and out

Hearing problems

Lots of people with Down's syndrome have problems with their hearing. This is often temporary, but it can sometimes be permanent.

A build-up of fluid in the middle ear (glue ear) is a common cause of temporary hearing problems in children with Down's syndrome.

If your child has glue ear, they'll usually be referred to an ear, nose and throat (ENT) specialist.

Vision problems

Many people with Down's syndrome also have problems with their eyesight and often need to wear glasses.

Common eye problems include:

  • short-sightedness – where distant objects appear blurred
  • long-sightedness – where nearby objects appear blurred
  • squint
  • eye infections, such as conjunctivitis, uveitis or blepharitis
  • cataracts – where the transparent structure that sits just behind your pupil (the lens) clouds over
  • nystagmus – where the eyes move uncontrollably, usually from side to side
  • keratoconus – where the clear outer layer at the front of the eyeball (the cornea) becomes thin and bulges out
  • glaucoma – increased pressure in the eye

Thyroid problems

Around 1 in 10 people with Down's syndrome have problems with their thyroid gland. This is responsible for controlling your metabolism, the rate at which your body uses up energy.

Most people with Down's syndrome who have a problem with their thyroid have hypothyroidism, which means their thyroid gland is underactive.

Symptoms of an underactive thyroid gland can include:

  • lack of energy
  • weight gain
  • slow physical and mental reactions

Hypothyroidism is usually picked up by blood tests. It can usually be treated with medication to replace the lack of thyroid hormone in the body.


People with Down's syndrome are more likely to develop infections, such as the lung infection pneumonia. This is because the body's natural defence against infection (the immune system) hasn't developed properly.

As well as routine childhood vaccinations, your child may be offered extra vaccinations, such as the annual flu jab, to help protect them from infections.

If your child develops a bacterial infection, a course of antibiotics will usually be prescribed to treat it.


People with Down's syndrome tend to develop dementia at a younger age, usually from about the age of 40 onwards. But not everyone with Down's syndrome will develop it.

Possible signs of dementia include problems with short-term memory and understanding, confusion, and disorientation.

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The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.
Last Updated: 22/11/2017 11:01:58