Down’s syndrome


Down’s syndrome


Down's syndrome, also known as Down syndrome, is a genetic condition that typically causes some level of learning disability and characteristic physical features.

Around 775 babies are born with the condition each year in England and Wales.

Many babies born with Down's syndrome are diagnosed with the condition after birth and are likely to have:

reduced muscle tone leading to floppiness (hypotonia)

eyes that slant upwards and outwards

a small mouth with a protruding tongue

a flat back of the head

a below average weight and length at birth

Although children with Down's syndrome share some common physical characteristics, they do not all look the same. A child with Down's syndrome will look more like their mother, father or other family members than other children with the syndrome.

People with Down's syndrome also vary in personality and ability. Everyone born with Down's syndrome will have a degree of learning disability, but the level of disability will be different for each individual.


Screening for Down's syndrome

In some cases, babies with the condition are identified before birth as a result of screening for Down's syndrome.

Screening tests can't tell you for definite if your baby has Down's syndrome, but they can tell you how likely it is. If screening suggests there is a chance your baby does have Down's syndrome, further tests can be carried out during pregnancy to confirm it.

If testing indicates your child will be born with Down's syndrome, you should be offered genetic counselling to allow you and your partner to discuss 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, who can also tell you more about the condition and answer any questions you may have.

What causes Down's syndrome?

Down's syndrome is caused by the presence of an extra copy of chromosome 21 in a baby's cells.

In the vast majority of cases, this isn't inherited, and is simply the result of a one-off genetic mistake in the sperm or egg.

There is a small chance of having a child with Down's syndrome with every pregnancy, but the risk increases with the age of the mother. For example, a woman who is 20 has about a one in 1,500 chance of having a baby with the condition, while a woman who is 40 has a one in 100 chance.

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

Life with Down's syndrome

Although there is no "cure" for Down's syndrome, there are ways to help children with the condition develop into healthy and fulfilled individuals who are able to achieve a level of independence right for them. This includes:

access to good healthcare, including a range of different specialists

early intervention programmes to provide support for children and parents

good parenting skills and an ordinary family life

education and support groups to provide information and help for parents, friends and families

Improved education and support has led to more opportunities for people with Down's syndrome. These include being able to leave home, form new relationships, gain employment and lead largely independent lives.

However, it is important to remember that each child is different and it is not possible to predict how individuals will develop.

Associated health conditions

There are a number of disorders that are more common in people with the condition. These include:

hearing and vision problems

heart disorders, such as congenital heart disease

thyroid problems, such as an underactive thyroid gland (hypothyroidism)

recurrent infections, such as pneumonia

Your child may 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, discuss them with your GP, health visitor or paediatrician.

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.

Characteristics of Down's syndrome 

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 protruding tongue

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 (single transverse palmar crease)

a below average weight and length at birth

However, it's important to note that people with Down's syndrome do not all look the same and will share physical features with 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 the condition may be slower to learn skills such as:






A child with Down's syndrome will gain these skills eventually, it simply takes more time.

Around one in every 10 children also experience additional difficulties such as autism spectrum disorder (ASD) or attention deficit hyperactivity disorder (ADHD).

Due to these problems, children with Down's syndrome often require extra support as they grow up and additional help at school.

Health problems

While many children and adults with Down's syndrome have few other health problems, there are a number of conditions that occur more frequently in people with Down's syndrome.

These include problems with the heart and bowel, difficulties with hearing and vision, and an increased risk of infections.


Causes of Down's syndrome 

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


The human body is made up of cells that contain genes. Genes are grouped in thread-like structures called chromosomes.

Chromosomes are blocks of DNA and contain detailed genetic instructions responsible for a wide range of factors, including:

how the body's cells develop

the colour of the eyes

the sex of a baby

Usually, cells contain 46 chromosomes. A child inherits 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, as there is an extra copy of chromosome 21. The additional genetic material causes physical and developmental characteristics associated with Down's syndrome.

 Types of Down's syndrome 

There are three forms of Down's syndrome, although the effects of each type are usually very similar.

Trisomy 21 is the most common type, affecting around 94% of people with Down's syndrome. It's where every cell in the body has an extra copy of chromosome 21.

Translocation is where an extra piece of chromosome 21 attaches itself to another chromosome. It affects around 4% of people with Down's syndrome. In this situation, there are only 46 chromosomes in each cell but one of them has extra material attached, so the total amount of genetic material in the cell is similar to that seen in a trisomy.

Mosaicism is the least common type, affecting around 2% of people with Down's syndrome. Only some of the cells have an extra copy of chromosome 21, which can mean people with mosaic Down's syndrome experience less delay with some aspects of their development.

In the vast majority of cases, Down's syndrome isn't inherited, and is simply the result of a one-off genetic mistake in the sperm or egg.

However, in some cases caused by the translocation of chromosome 21, the genetic mistake is passed on from one of the child's parents, even if they have no signs of Down's syndrome themselves.

 What are the chances of having an affected pregnancy? 

With every pregnancy, there is a small chance of having a child with Down's syndrome.

There's currently no clear evidence to suggest that anything done before or during pregnancy increases or decreases this risk, although some people are more likely to have a child with Down's syndrome than others.

The main factor that increases the chance of having a baby with Down's syndrome is the age of the woman when she becomes pregnant. For example, a woman who is:

20 years of age has a risk of one in 1,500

30 years of age has a risk of one in 800

35 years of age has a risk of one in 270

40 years of age has a risk of one in 100

45 years of age has a risk of one in 50 or greater

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

The chance of having a child with Down's syndrome is also increased if you have previously had an affected pregnancy. For most people this risk is still small (around one in 100), although this may be as high as one in 10 if you or your partner have the altered genes that can lead to the translocation of chromosome 21.

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

 Screening for and diagnosing Down's syndrome  

Screening during pregnancy can determine the likelihood of a baby being born with Down's syndrome, but in many cases the condition is only diagnosed after birth.

Screening during pregnancy

All pregnant women should be offered screening for genetic conditions such as Down's syndrome. Antenatal screening assesses the likelihood of your baby developing abnormalities.

Screening cannot definitively diagnose Down's syndrome, but it can help with the decision to have further tests. However, no test is 100% accurate and it's possible for potential problems to remain undetected during screening.

Screening for Down's syndrome should ideally be carried out before the end of your first trimester (14 weeks and one day). Most women are screened between 11 and 14 weeks. However, if necessary, it's possible to have screening up to 20 weeks into your pregnancy (this will involve a different test – known as the "quadruple blood test").

Combined test

The main screening test used for Down's syndrome is known as the "combined test". It includes:

a blood test to check the levels of certain proteins and hormones, as abnormal levels of these substances could mean there is an increased risk of your baby having Down's syndrome

an ultrasound scan (known as a nuchal translucency scan) to measure the size of the pocket of fluid behind your baby's neck, as babies with Down's syndrome usually have more fluid in their neck than normal

The results of these two tests will be used, along with your age, to help determine the chances of your child having Down's syndrome. If this risk is found to be high (at least a one in 150 chance), you will be offered further tests to confirm whether your baby has the condition.

Quadruple blood test

If it has not been possible for you to have the combined screening test in early pregnancy, you will be offered a blood test between 14 and 20 weeks.

This test is called the quadruple test because it measures four hormones associated with pregnancy. This information is combined with your age and used to work out your individual chance of having a baby with Down's syndrome.

Diagnosis during pregnancy

There are two main tests used to diagnose a baby with Down's syndrome while it's still in the womb. These are:

chorionic villus sampling (CVS) – a small sample of the placenta (an organ attached to the lining of your womb during pregnancy) is removed with a needle or tube for examination; this is usually done from week 11 of pregnancy

amniocentesis – a small sample of amniotic fluid (the fluid that surrounds the foetus in the womb) is removed with a needle for examination; this is usually carried out from week 15 of pregnancy

Make sure you discuss the benefits and risks of having either of these procedures with your doctor or midwife beforehand though, as both tests are thought to have around a one in 100 chance of causing amiscarriage.

Getting the results

The results of CVS or amniocentesis are normally available within a few days.

If the test shows that your baby is unlikely to have Down's syndrome, your pregnancy should continue as normal.

If you are told that it's likely your baby does have Down's syndrome, you should be offered genetic counselling to allow you and your partner to discuss the impact of the diagnosis on you, and talk about the available options.

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

This will help you make an informed choice about how to proceed with the pregnancy.

Diagnosis after birth

Once your baby is born, an initial diagnosis of Down's syndrome is usually based on your baby's appearance, as there are often clear physical characteristics of Down's syndrome.

If your doctor needs to confirm the diagnosis, a sample of your child's blood can be taken and analysed to look for the extra copy of chromosome 21 that causes Down's syndrome.

Living with Down's syndrome

Having Down's syndrome, or having a child with the condition, can be challenging at times. But with help and support, most people are able to have healthy, active and more independent lives.

Emotional impact

In some cases, it may not be apparent a baby has Down's syndrome until after they are born. Giving birth can be exciting, scary and tiring, and finding out that your baby has Down's syndrome can be unexpected and alarming.

Some families accept their baby's diagnosis of Down's syndrome quickly, while others need time to adjust.

If you have recently found out your child has Down's syndrome, you may feel a range of emotions, such as fear, sadness or confusion. It is quite common for parents to feel overwhelmed or have negative thoughts after the birth of their new baby.

There is no right or wrong way to react. Finding out more about the condition will give you a better understanding about how it may affect your child's life, as well as your own.

Support groups

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

Many parents find it reassuring to talk to other parents. The Down's Syndrome Association can put you in touch with another family who can share their experiences with you, offer you advice and talk through any fears or concerns you may have. They can also provide information about all aspects of living with Down's syndrome.

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 a number of things you can do on a daily basis to help your child with their learning and development. What helps will depend on the skills your baby has trouble with, but things that may be useful include:

use play to help your child learn – for example, show them how to play with their toys and use toys to help encourage them to reach, grasp and move

name and talk about the things your child is looking at and is interested in

give your child the opportunity to mix with other children

encourage your child to be as independent as possible from an early age with activities such as feeding and dressing, getting ready for bed, brushing teeth, going to the toilet

play games to teach vocabulary and word recognition – a home visiting teacher or speech and language therapist (see below) can give you some ideas

However, it's important to find a balance between "special" activities and normal things families do to ensure your child grows up within a happy, loving and active family environment.

As with all new babies, at times they will need to fit in with what is going on around them and the needs of other family members. Not everything you do with your baby needs to be educational or meaningful. Any fun activity with 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 is having.

For many people this will involve an early intervention programme, which 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 also be advised about things you can do at home to help your child learn and develop, and you'll have the opportunity to find out about your child's condition and meet other families in similar situations.

Your paediatrician can give you further information about early intervention. You can also call the Down's Syndrome Association helpline on 0333 121 2300 for advice.


Increasing numbers of children with Down's syndrome are educated in mainstream nurseries or mainstream schools with support. However, individual needs vary and some parents feel that a special school will be most suitable for their child.

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

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

Regular health check-ups

Children and adults with Down's syndrome need regular check-ups to monitor their health because certain health problems are more common in people with the condition.

These check-ups will usually be with a paediatrician (a doctor who specialises in treating children) at first, although a GP may carry them out 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 a potential problem, they can refer you to an appropriate specialist to talk about any treatment or support that may benefit your child.

Adults with Down's syndrome

Further education and employment

Many young adults with Down's syndrome pursue further education. Some also gain employment, usually on a part-time basis, but this will depend on the individual.

Living independently

With help and support, many adults with Down's syndrome are able to lead an active and fairly independent life. Although it may not be possible to live completely independently, increasing numbers of adults with Down's syndrome are leaving home and living in their communities with support.

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

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

Relationships, sex and fertility

Many people with Down's syndrome enter loving relationships, although they may need guidance and support when it comes to things such as contraception.

Men and women with Down's syndrome tend to have a reduced fertility rate. This does not mean they cannot conceive 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 physical and mental demands of a newborn baby.

If one partner in a couple has Down's syndrome, there is around a one in two chance of each of their children having Down's syndrome too. The risk of miscarriage and premature birth is also greater in women with Down's syndrome.

Complications of Down's syndrome 

Some children with Down's syndrome have very few health problems as a result of their condition. Others will experience several of the more common health conditions and 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, discuss them with your GP, health visitor or paediatrician.

Some of the main complications associated with Down's syndrome are outlined below.

Heart problems

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

The most common defect to affect children with Down's syndrome 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".

It can cause a build-up of blood in one or more of the heart's chambers, which causes the heart to work harder to pump blood through the four chambers.

If your baby is diagnosed with Down's syndrome, their heart will be carefully assessed to detect any problems as soon as possible. If a problem is found, surgery will often be needed to repair the heart.

Gut problems

Many people with Down's syndrome have some sort of problem with their digestive system. Constipation, diarrhoea and indigestion are all common, as are more serious problems such as small bowel obstruction, which stops food passing from the stomach into the large bowel.

Some children also develop coeliac disease (a condition where a person has an adverse reaction to gluten) and reflux (bringing up milk during or shortly after feeding).

Conditions such as imperforate anus (where a baby is born without an anal opening) or Hirschsprung's disease (where the large bowel is unable to push faeces towards the anus) are rare, but slightly more common in children with Down's syndrome.

Hearing problems

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

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

If your child has glue ear, they will usually be referred to an ear, nose and throat (ENT) specialist for further assessment. For some children, glue ear can be treated with minor surgery, which involves placing small tubes called grommets in the ear to help drain away the fluid.

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


eye infections, such as conjunctivitis, uveitis or blepharitis

cataracts – where the lens (the transparent structure that sits just behind your pupil) clouds over

nystagmus – where the eyes move uncontrollably, usually from side to side

keratoconus – where the cornea (clear outer layer at the front of the eyeball) becomes thin and bulges out

glaucoma – increased pressure in the eye


Thyroid problems

Around one in 10 people with Down's syndrome have problems with their thyroid gland. The thyroid gland is located in the neck and is responsible for controlling your metabolism (the rate at which your body uses up energy). It does this by releasing thyroid hormones into the body.

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:

lethargy (lack of energy)

weight gain

slow physical and mental reactions

Thyroid problems will usually be picked up during blood tests and can often be treated with medication to replace the lack of thyroid hormone in the body.

Increased risk of infections

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

To reduce the risk of infections, routine childhood vaccinations will be recommended, as may the annual flu jab.

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


There is a tendency for people with Down's syndrome to developdementia at a younger age than in the general population, usually from about 40 years of age onwards, although it's not inevitable that everyone with Down’s syndrome will develop it.

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


Down's syndrome