Down syndrome

Also known as trisomy 21

Key points about Down syndrome

  • Down syndrome is a genetic disorder you are born with where you get an extra copy of chromosome 21.
  • Everyone with Down syndrome is unique and experiences different features and/or challenges.
  • The chance of your baby having Down syndrome is 1 in 1000, increases with the mother's age and can be diagnosed antenatally (before birth) or postnatally (after birth). 
  • Down syndrome does not run in the families in most cases.
  • There is no cure for Down syndrome.
  • Adults with Down’s syndrome lead longer, more healthy, fulfilling and varied lives than in the past.
  • There are support groups available.
Young girl with Down syndrome and colourful paint on fingers
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Each cell in the human body contains 46 chromosomes arranged in 23 pairs. One pair is inherited from the father and the other pair is inherited from the mother. Down syndrome is a condition where you have 3 copies of chromosome 21. There are 3 ways this can happen:

  • Trisomy 21 – you get an extra copy of chromosome 21 in all your body cells due to abnormal cell division. This accounts for 94% of Down syndrome cases.
  • Mosaic Down syndrome – only some of your body cells contain an extra copy of chromosome 21. This accounts for 1% of cases.
  • Translocation Down syndrome – the remaining cases are due to translocation, in which a portion of chromosome 21 becomes attached to another chromosome, resulting in the cells having 3 copies of chromosome 21. 

Image credit: 123rf

It’s not known exactly why these abnormal cell divisions happen. The chances of having a baby with Down syndrome increase with the mother's age. However because most women have children at a younger age, 70% of Down syndrome infants are born to mothers aged under 35 years. In most cases, Down syndrome does not run in the family. 

Everyone with Down syndrome is different and not all people with Down syndrome have the same features or difficulties.

Typical physical features of Down syndrome include:

  • small head or flattened back of the head (occiput)
  • short neck
  • small nose and flattened nose bridge
  • flattened face
  • extra skin fold on the upper eyelid (epicanthal fold)
  • upward slanted eyes
  • protruding tongue
  • low-set or small ears
  • short height
  • single crease on the palm of the hand
  • broad, short hands
  • short fingers or inward curving of little finger
  • poor muscle tone
  • delayed and slow growth
  • large gap between the first and second toe.

Down syndrome can cause certain medical problems. These include:

  • congenital heart problems such as atrioventricular septal defect (a hole in the muscle that separates the heart chambers)
  • gastrointestinal problems such as duodenal atresia
  • vision problems such as cataracts, short-sightedness
  • ear infections and hearing problems 
  • teeth and bone developmental problems
  • cancer such as leukemia
  • underactive thyroid gland
  • diabetes
  • reduced fertility.

Children with Down syndrome will have some level of intellectual disability and behavioural problems. These range from mild to moderate or severe. Some common difficulties include:

  • delayed speech and language development
  • feeding difficulties
  • delayed motor development such as sitting, walking and crawling
  • low intellectual quotient (IQ).

Down syndrome can be diagnosed antenatally (before birth) or postnatally (after birth). 

During pregnancy, Down syndrome can be diagnosed by screening and diagnostic tests. Screening tests for Down syndrome include a blood test (MSS1) and an ultrasound scan to check the fluid thickness behind your baby's neck. These are typically done if you are less than 14 weeks pregnant. If you are between 14 and 20 weeks pregnant, a screening blood test (MSS2) will be done. MSS stands for maternal serum screening (a blood test from the mother).

If the results of the screening tests show that your baby is at increased risk of having Down syndrome, diagnostic tests such as chorionic villus sampling or amniocentesis can be done, depending on the week of gestation. Read more about antenatal tests for Down syndrome(external link)(external link) and pregnancy screening for Down syndrome and other conditions(external link)(external link).

After birth, Down syndrome is usually suspected if your baby has the typical facial features. It can be confirmed by genetic tests to look for the extra copy of chromosome 21. 

There is no cure for Down syndrome. Treatment aims to monitor the condition and support people with Down syndrome lead a normal life, including to manage the challenges associated with the condition. People living with Down syndrome also need regular follow-ups to monitor complications and get treated if needed. 

There are different types of healthcare providers that may be involved in your child's care. These include:

  • paediatricians
  • speech and language therapist
  • physiotherapists
  • dentists
  • GPs
  • occupational therapist
  • cardiologist.

In general, the earlier the treatment or support is provided, the better the long-term outcome for a person living with Down syndrome. 

As your child grows, it is important to see the person first, not their condition. Children with Down syndrome develop at different rates and in different ways – they will have individual strengths, interests, talents and needs. It helps them to be socially included in their families, schools and communities. Their involvement brings rewards to those groups too.

Your child will develop by taking part in enjoyable opportunities for interacting, moving and playing in their first years of life. As they get older they will continue to progress in all areas. This development can be helped by early intervention, having their hearing and any other health needs met and, later, by being educated at school. The Down Syndrome Association(external link)(external link) has more advice and support for parents. 

With recent medical advances and earlier detection of Down syndrome, at least half of people with Down syndrome are able to lead a normal active life and live into their 50s and 60s. 

The most common causes of death for people living with Down syndrome are congenital heart problems. 

It can be difficult to cope if you have a child with Down syndrome. There are support groups available where you can listen to other people's stories and get the support you need. If you are planning to have a baby and are concerned about the risk of having a baby with Down syndrome, talk to your GP and they may be able to refer you to a genetic counsellor. 

NZ Down Syndrome Association(external link)(external link) Freephone 0800 693 724
Find more support groups here.

These videos may take a few moments to load.

Video: Keeping up with Chris: Excelling with Down syndrome

When Chris Bunton was born with Down syndrome his parents wondered if he’d ever achieve the independence they dreamed of … but he has exceeded all their expectations. At just 22 years old, Chris combines part-time work with university study as well as a demanding gymnastics training programme. Chris invites us into his busy life in Sydney, while his parents share insights they have gained from raising an independent son.

(Attitude Live, NZ, 2016)

Video :Luke

Luke has Down syndrome and is one of the most compassionate and funniest 9-year-olds in Canterbury. He loves swimming, football and playing with the family dogs.

(Attitude Live, NZ)

Video: Independence with Down syndrome

Alex Sneddon’s parents have always wanted the best for their son. From early on they helped him to create the kind of life he wanted. Now the 24-year-old who lives with Down syndrome is holding down four jobs and living an independent life.

(Attitude Live, NZ, 2016) 

Video: Living independently with Down syndrome

Clayton Marr is a confident, sporty and independent 21 year old. This year he's vying for a gold medal at the Athens Special Olympics. Attitude Live spent some time getting to know him on his family vinyard in Nelson.

(Attitude Live, NZ, 2012) 

Video: Independence with Down syndrome: Kelly's Story

Kelly Fitzgerald is one of only two people in New Zealand with Down syndrome that have their full driver's licence.

(Attitude Live, NZ, 2009)

Video: The Lily Harper Show: Living with Down syndrome

Hosting her own chat show, Lily Harper interviews herself, getting the low down on life as an independent woman and Special Olympic athlete who lives with Down syndrome.

(Attitude Live, NZ, 2016)

From the moment of diagnosis in utero, what is it like to raise a child with Down syndrome? The hopes, dreams and worries of a family and the wonder of development are tracked in this very honest documentary, following a little boy from day dot till 5 years.

Video: Raising a child with Down syndrome

Watch on Youtube(external link) (Attitude, NZ, 2016)

Video: Growing up with Down syndrome

"In this video, Dylan is three and about to embark on his first day of pre-school."

(Attitude Live, NZ, 2016)

In this video series from Kidshealth NZ, Melanie Mora introduces her family – husband Richard and their three sons: Jamie, Ryan and Ethan. Her second son Ryan was diagnosed post-birth with Down syndrome.

Video: Introducing Melanie Mora - a mother's perspective on having a child with Down syndrome

Melanie introduces herself and talks about her smooth transition from a career-driven lifestyle to a family-oriented lifestyle. This video may take a few moments to load.

(Kids Health NZ, 2012)

Video: The first 24 hours after Down syndrome diagnosis

Mel talks about the first 24 hours after receiving the unexpected news that her newborn son Ryan was being tested for Down syndrome. 

(Kids Health NZ, 2012)

Video: Being positive after Down syndrome diagnosis

Early on, following the diagnosis, Mel and her husband put on a brave face and projected positivity because they knew others would take their cues from them.

(Kids Health NZ, 2012)

Video: How others see Ryan- a child who has Down syndrome

Mel discusses other children's reactions to Ryan. She says that kids don't see the same differences that adults do. Mel thinks that as each generation comes through with more exposure to the host of health issues that are out there facing children, there'll be more empathy and they'll be better people for it. This video may take a few moments to load.

(Kids Health NZ, 2012)

Video: The challenges of having a child with Down syndrome

Mel talks about the challenges associated with raising Ryan. This video may take a few moments to load.

(Kids Health NZ, 2012)

Video: Mel describes her parenting style with her son Ryan who has Down syndrome

Mel says one of the hard things about having a child with special needs is that you become more conscious as a parent. More input is required to help your child meet developmental milestones. Mel says the best thing you can do for your child is to let them know they are loved and accepted. This video may take a few moments to load.

(Kids Health NZ, 2012)

Video: Impact of having a child with Down syndrome on Mel and her husband as a couple

Mel discusses how having Ryan has affected her relationship with her husband. She says when you're faced with challenges you dig deep. Mel and Richard's relationship has strengthened as a result. This video may take a few moments to load.

(Kids Health NZ, 2012)

Video: The impact of Down syndrome on siblings

Mel discusses the impact of having a child with special needs on siblings. She thinks that for siblings, learning everyone is different and has different needs can only be a positive thing. This video may take a few moments to load.

(Kids Health NZ, 2012)

Video: The importance of looking after yourself when you have a child with Down Syndrome

Mel stresses that when you have a child with special needs, it is particularly important to stay strong, focus on the big picture and look after yourself and your relationship. This video may take a few moments to load.

(KidsHealth, NZ, 2012)

The following links provide further information about Down syndrome. Be aware that websites from other countries may have information that differs from New Zealand recommendations.

NZ Down Syndrome Association(external link)
Down syndrome(external link)
 NHS Choices, UK
Down's syndrome(external link) Patient Info, UK


Trisomy 21 (Down syndrome) [PDF, 438 KB] New Zealand Maternal Fetal Medicine Network, 2015


  1. Down syndrome (external link)Auckland Regional HealthPathways, NZ
  2. Down syndrome(external link) NHS Choices, UK
  3. Down's syndrome(external link) Patient Info, UK
  4. Children, families, and education(external link) Down Syndrome Association, UK


trisomy 21 down syndrome

Trisomy 21 (Down syndrome)

New Zealand Maternal Fetal Medicine Network, 2015

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Reviewed by: Sarah Godsell, community nurse, Auckland DHB

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