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The NHS offers all pregnant women screening for Down’s syndrome during pregnancy. The standard pathway begins with the combined test at 11 to 14 weeks. Those with a high-chance result are offered NIPT or diagnostic testing. This guide explains the full pathway and what the results mean.
The NHS offers a programme of screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome to all pregnant women in England. Screening is voluntary and all women have the right to choose whether or not to be screened. The standard first-line screening test is the combined test, offered between 11 and 14 weeks of pregnancy. Women who receive a high-chance result from the combined test are offered further testing, which may include non-invasive prenatal testing (NIPT) or a diagnostic test such as amniocentesis or chorionic villus sampling. The aim of screening is to give families information about the probability of Down’s syndrome in their pregnancy, allowing them to make informed decisions about further testing and, if a diagnosis is confirmed, about the pregnancy itself.
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The NHS combined test is offered between 11 and 14 weeks of pregnancy. It combines a blood test that measures the levels of two proteins in the mother’s blood with an ultrasound scan that measures the nuchal translucency, the fluid at the back of the baby’s neck. The results are combined with maternal age to calculate a risk figure for the pregnancy. A result of 1 in 150 or higher is considered high chance under the NHS threshold.
Women who receive a high-chance combined test result are offered NIPT on the NHS before proceeding to invasive diagnostic testing. NIPT analyses fragments of fetal DNA circulating in the mother’s blood and can detect Down’s syndrome with a sensitivity of over 99 percent. Private NIPT is available from 10 weeks gestation without a prior high-chance result. NIPT is a screening test, not a diagnostic test: a high-chance NIPT result should be confirmed by an invasive diagnostic test before any clinical decision is made.
A high-chance result from the combined test or NIPT does not mean the baby has Down’s syndrome: it means the probability of Down’s syndrome is above the NHS threshold. Many pregnancies with a high-chance result do not have Down’s syndrome. A high-chance result is an indication for further testing rather than a diagnosis. Women with a high-chance result will be offered a discussion with a specialist midwife and an explanation of the options, including NIPT if not already carried out, amniocentesis, CVS or no further testing.
Amniocentesis and CVS are diagnostic tests that provide a definitive chromosomal result. Amniocentesis analyses chromosomes from a sample of amniotic fluid and is offered from around 15 weeks. CVS analyses chromosomes from the placenta and can be performed from around 11 weeks. Both tests carry a small risk of miscarriage: approximately 0.5 to 1 percent for amniocentesis and approximately 1 to 2 percent for CVS. They are offered to women with a high-chance screening result who wish to have a definitive answer.
A low-chance result from the combined test means the probability of Down’s syndrome has been calculated as below the NHS threshold. This does not mean Down’s syndrome is impossible: it means it is less likely than the threshold figure. Most pregnancies with a low-chance result will not have Down’s syndrome. However, around 85 percent of babies born with Down’s syndrome are born to women who received a low-chance screening result, because most pregnancies are in the low-chance category and no screening test has 100 percent sensitivity.
All screening is voluntary. Women and their partners have the right to accept or decline any part of the screening programme without affecting the care they receive during the pregnancy. The decision whether to screen, whether to proceed to diagnostic testing following a high-chance result and what decision to make following a confirmed diagnosis of Down’s syndrome are all deeply personal. The NHS commits to providing information in a balanced and non-directive way, and specialist support is available through antenatal teams, the Down’s Syndrome Association and other organisations.
For related information see our articles on NIPT for Down’s Syndrome and Down’s Syndrome Diagnosis.
Yes. The NHS offers screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome to all pregnant women in England as part of the Fetal Anomaly Screening Programme. The standard first-line test is the combined test at 11 to 14 weeks. Screening is voluntary and women can choose whether or not to be tested.
A high-chance result means the probability of Down’s syndrome is above the NHS threshold of 1 in 150. It does not mean the baby has Down’s syndrome. You will be offered a referral to discuss the options with a specialist, which typically include NIPT, amniocentesis, CVS or choosing not to have further testing. A specialist midwife or fetal medicine team will explain the options, the risks involved and what a diagnosis would mean.
Yes. No screening test detects 100 percent of cases. The NHS combined test identifies a proportion of Down’s syndrome pregnancies but not all. NIPT has higher sensitivity but is also not 100 percent. NCARDRS data confirms that approximately 85 percent of pregnancies diagnosed with Down’s syndrome antenatally are terminated, meaning the majority of babies born with Down’s syndrome are born to women who either did not screen, had a low-chance result or chose not to have diagnostic testing following a high-chance result.
Visit our Understanding Down’s Syndrome hub for more guides on causes, diagnosis, education, health conditions and independent living.
The information in this article is provided for educational purposes only and is not intended as medical advice. If you have concerns about Down’s syndrome or any health condition, speak to a qualified healthcare professional. SENDhelp Education Limited accepts no responsibility or liability for any loss or damage arising from reliance on this content. Any links to third-party websites are provided for convenience only and do not constitute endorsement of their content.
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