Down바카라 사이트s syndrome, Edwards바카라 사이트 syndrome and Patau바카라 사이트s syndrome
Updated 15 April 2025
Applies to England
Β© Crown copyright 2025
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This short animation explains screening for Down바카라 사이트s syndrome, Edwards바카라 사이트 syndrome and Patau바카라 사이트s syndrome in pregnancy.
1. Purpose of screening
To find out how likely it is that your baby has Down바카라 사이트s syndrome (Trisomy 21 or T21), Edwards바카라 사이트 syndrome (Trisomy 18 or T18) or Patau바카라 사이트s syndrome (Trisomy 13 or T13).
Screening is your choice. You do not have to have the screening test. Some people want to find out if their baby has one of the conditions and some do not. Screening is not perfect and might provide an incorrect result. It may lead to personal choices about your pregnancy.
If you choose to have screening, you can be screened for:
- all 3 conditions
- Down바카라 사이트s syndrome only
- Edwards바카라 사이트 syndrome and Patau바카라 사이트s syndrome only
This screening will be offered if you바카라 사이트re having one baby or twins.
2. Overview of screening
The screening process may involve several different tests.
The first screening test is called the combined test (or the quadruple test if you are later in your pregnancy). You may then be offered a second type of screening test called NIPT (non-invasive prenatal testing). Following either of these screening tests you may be offered a diagnostic test to confirm whether or not the baby has one of the conditions.
Find more information about , and on the NHS website.
3. About these conditions
Inside the cells of our bodies there are tiny structures called chromosomes. These are made of DNA (genetic material). They carry the genes that determine how we develop. There are 23 pairs of chromosomes in each cell. Changes can occur in the sperm or egg cells, which can lead to a baby having an extra chromosome.
Babies with Down바카라 사이트s syndrome, Edwards바카라 사이트 syndrome or Patau바카라 사이트s syndrome are born to mothers of all ages but the chance of having a baby with one of the conditions increases as the mother gets older. They are all caused by having an extra copy of a chromosome in some or all cells of the body. Having the extra chromosome in just some cells is called the mosaic form and can lead to milder effects for the child. Screening cannot identify which form or what level of disability your baby will have.
3.1 Down바카라 사이트s syndrome (T21)
Down바카라 사이트s syndrome is caused by an extra copy of chromosome 21 in all or some cells of the body. A person with Down바카라 사이트s syndrome will have some level of learning disability. This means they will find it harder than most people to understand and to learn new things. They may have communication challenges and difficulty managing some everyday tasks. People with Down바카라 사이트s syndrome have distinctive facial features but they do not all look the same.
A child with Down바카라 사이트s syndrome
Most children with Down바카라 사이트s syndrome attend mainstream schools but will require additional support. Some health problems are more common in people with Down바카라 사이트s syndrome. These include heart conditions and problems with hearing and vision. Many health problems can be treated but unfortunately around 5% of babies will not live past their first birthday.
For babies without serious health problems survival is similar to that of other children and most people with Down바카라 사이트s syndrome will live into their 60s or longer.
People with Down바카라 사이트s syndrome can have a good quality of life and most say they enjoy their lives. With support, many more people with Down바카라 사이트s syndrome are able to get jobs, have relationships and live semi-independently in adulthood.
3.2 Edwards바카라 사이트 syndrome (T18) and Patau바카라 사이트s syndrome (T13)
Babies with Edwards바카라 사이트 syndrome have an extra copy of chromosome 18 in all or some cells. Babies with Patau바카라 사이트s syndrome have an extra copy of chromosome 13 in all or some cells.
Sadly the survival rates are low and of those babies born alive only around 13% with Edwards바카라 사이트 syndrome and 11% with Patau바카라 사이트s syndrome will live past their first birthday. Some babies may survive to adulthood but this is rare.
All babies born with Edwards바카라 사이트 syndrome and Patau바카라 사이트s syndrome will have a learning disability and a wide range of physical challenges, which can be extremely serious. They may have problems with their heart, respiratory system, kidneys and digestive system.
Around half of babies with Patau바카라 사이트s syndrome will also have a cleft lip and palate. Babies with Edwards바카라 사이트 syndrome and Patau바카라 사이트s syndrome will have a low birthweight.
Despite their difficulties, children can slowly make progress in their development. Older children with either condition would need to attend a specialist school.
Down바카라 사이트s syndrome occurs in 10 in every 10,000 births. Edwards바카라 사이트 syndrome occurs in 3 in every 10,000 births. Patau바카라 사이트s syndrome occurs in 2 in every 10,000 births.
4. The first screening test
If you choose to have the combined test, it will involve:
- a blood sample taken from your arm between 10 and 14 weeks of pregnancy
- an ultrasound scan measurement of fluid at the back of your baby바카라 사이트s neck between 11 and 14 weeks of pregnancy 바카라 사이트 this is known as the nuchal translucency (NT)
This information is combined with your age to work out the chance of your baby having the condition. If you are more than 14 weeks pregnant the combined test is not appropriate. You will instead be offered:
- a blood test, called the quadruple test, between 14 and 20 weeks of pregnancy to screen for Down바카라 사이트s syndrome (this test is not as accurate as the combined test)
- a 20-week scan to screen for Edwards바카라 사이트 syndrome and Patau바카라 사이트s syndrome
5. Safety of the test
The screening test cannot harm you or your baby but it is important to consider carefully whether or not to have this test.
The test cannot tell you if your baby definitely has one of these conditions. It can provide information that may lead to further decisions about your pregnancy.
If you receive a higher-chance result from the first screening test, you may need to decide whether to have a second screening test or a diagnostic test that has a risk of miscarriage. If you have a diagnostic test, depending on the result, you may need to decide whether to continue your pregnancy or have a termination.
6. Possible screening results
Depending on what you asked for when you decided to have the screening test, we will give you one or both of:
- a result for Down바카라 사이트s syndrome
- a joint result for Edwards바카라 사이트 syndrome and Patau바카라 사이트s syndrome
A lower-chance result means it is unlikely, though still possible, that your baby will have the condition. Most screening test results (around 97% of them) are lower chance.
A higher-chance result means it is more likely, but not certain, that your baby will have the condition. Overall, around 3% of screening test results are higher chance.
We will give each result as a chance, for example your baby has 바카라 사이트1 chance in 150바카라 사이트 of being born with Down바카라 사이트s syndrome. The bigger the second number (such as 150), the smaller the chance your baby has of being born with the condition. So 바카라 사이트1 chance in 200바카라 사이트 is smaller than 바카라 사이트1 chance in 100바카라 사이트.
A 바카라 사이트lower-chance바카라 사이트 result is 1 chance in 151 or more, for example 1 chance in 300. A 바카라 사이트higher-chance바카라 사이트 result is 1 chance in up to 150, for example 1 chance in 100.
To understand what, for example, 바카라 사이트1 chance in 300바카라 사이트 means, imagine a group of 300 women. One of these women will be pregnant with a baby that has the condition.
7. Not having the test
If you choose not to have the screening test for Down바카라 사이트s syndrome, Edwards바카라 사이트 syndrome and Patau바카라 사이트s syndrome, the rest of your antenatal care will be unaffected.
Any scan during your pregnancy may pick up physical problems with your baby which could be related to these conditions. You will always be told if anything unexpected is found during a scan.
8. Getting my results
If your screening test shows a lower-chance result, you will be told within 2 weeks of the test being taken. If your screening test shows a higher-chance result, you will be told within a week of having the test. You will be offered an appointment to discuss:
- the test results and what they mean
- the condition your baby may have
- the choices available to you
9. Further tests
If you have a lower-chance result you will not be offered a further test. If you have a higher-chance result, you may decide:
- not to have any further testing
- to have a second screening test (called NIPT) to obtain a more accurate screening result before choosing whether or not to have a diagnostic test
- to have a diagnostic test straight away
Your decisions will be respected and health care professionals will support you. You should speak up if you feel your decisions are not being respected. Information is also available from support organisations. Whatever results you get from any of the screening or diagnostic tests, you will get support and care to help you decide what to do next.
10. The second screening test (NIPT)
The second screening test is another blood test called NIPT (non-invasive prenatal testing). NIPT is more accurate than the combined or quadruple test, though it is not quite as accurate in twin pregnancies. It works by measuring DNA (genetic material) in your blood. Some of this DNA will be from the baby바카라 사이트s placenta. If there is more DNA than expected from chromosomes 21, 18 or 13 it may mean that your baby has Down바카라 사이트s syndrome, Edwards바카라 사이트 syndrome or Patau바카라 사이트s syndrome. Like every screening test, though, it does not give a definite answer. NIPT cannot harm your baby. Most women will get their result within 2 weeks.
Most people will get a lower-chance result, meaning your chance of having a baby with the condition is low. You will not be offered a diagnostic test.
If your NIPT result shows a higher-chance result then the chance of your baby having the condition is high. You will then be offered a diagnostic test, though it is up to you whether or not to have this. In a small number of cases, NIPT might produce no result. You can then choose between one further NIPT, a diagnostic test or no further testing.
11. The diagnostic test (CVS or amniocentesis)
Diagnostic tests give a definite answer. They test cells from the placenta or fluid surrounding your baby.
Diagnostic tests can find conditions other than Down바카라 사이트s syndrome, Edwards바카라 사이트 syndrome or Patau바카라 사이트s syndrome but this is rare. 1 out of 200 women (0.5%) who have a diagnostic test will miscarry as a result of the test. There are 2 types of diagnostic test: chorionic villus sampling (CVS) and amniocentesis.
11.1 CVS (chorionic villus sampling)
This is usually done from 11 to 14 weeks of pregnancy but can be done later. A fine needle, usually put through the mother바카라 사이트s abdomen, is used to take a tiny sample of tissue from the placenta.
11.2 Amniocentesis
This is usually done after 15 weeks of pregnancy. A fine needle is passed through the mother바카라 사이트s abdomen into the uterus to collect a small sample of the fluid surrounding the baby.
12. Results from the diagnostic test
Following the diagnostic test, some women will find out their baby has Down바카라 사이트s syndrome, Edwards바카라 사이트 syndrome or Patau바카라 사이트s syndrome. They can then choose to continue with the pregnancy or decide not to continue with the pregnancy and have a termination.
If you are faced with this choice you will get further information about the condition and support from health care professionals to help you make a decision.
Information is also available from support organisations.
Find on the NHS website.
13. About this leaflet
With grateful thanks to the Down바카라 사이트s Syndrome Association for permission to use the photograph above.