It has been possible for many years to find out if an unborn baby has a higher risk than normal of having a genetic condition or disability – such as Down Syndrome or a sickle cell disorder – using ultrasound scans and blood tests. The only way to find out whether or not a baby is affected is to have an invasive test such as amniocentesis, which involves fluid being extracted from the womb with a needle, and this carries a small risk of miscarriage.
Quite recently it was discovered that DNA in the cells of the placenta that circulate in the blood of the mother can be used to look at the baby’s DNA. So it is now possible to find out about the genetic make-up of the unborn baby by taking a blood sample from the mother from around 10 weeks of pregnancy – this is called non-invasive prenatal testing (NIPT).
NIPT can be used:
- To estimate the chance that a baby has an extra chromosome (which causes Down Syndrome, Patau Syndrome and Edwards Syndrome) more accurately than previously available screening tests. This kind of NIPT is widely available through private healthcare clinics, under brand names such as the Harmony™, MaterniT® 21 PLUS and verifi®. If NIPT suggests the baby has one of these conditions, an invasive test such as amniocentesis will be offered to confirm the diagnosis.
- To get a definite or near definite diagnosis of some genetic conditions, such as achondroplasia, when family history information or an ultrasound scan suggests the baby is at risk. This kind of NIPT is available on the NHS in some areas and through private clinics.
- To find out the sex of the baby. This is available through private clinics, and also through the NHS if there is a medical reason for finding out the sex (for example to find out about genetic conditions that only or mainly affect boys).
In January 2016, the UK National Screening Committee (UKNSC)recommended that NIPT for Down Syndrome, Patau Syndrome and Edwards Syndrome be offered on the NHS to pregnant women whose babies are found to be at high risk of having these conditions (following the 11-14 week screening tests). The UKNSC has proposed that this should be implemented as part of an evaluation process to understand better how offering NIPT in this way will affect the screening pathway and the choices that women make. The Government is currently deciding whether it should bring the test into standard NHS antenatal care, and if so, how this should be done.
Making NIPT available on the NHS may mean that, for women who choose to have screening tests and are found to be at high risk, fewer go on to have an invasive diagnostic test. This could reduce the risk of miscarriage caused by prenatal testing. Having the test available on the NHS will also mean women who cannot afford to pay for a private test will be able to use NIPT if they want to.
However, some people are concerned that women might feel they are expected or pressured to have NIPT because it is ‘risk free’, or that they may not realise what they are being tested for given the amount of other blood tests that are routinely carried out during pregnancy. There is also the worry that women may have NIPT without understanding that it is not 100 per cent accurate and that there can still be difficult decisions to be made afterwards about whether or not to have an invasive test. Some people are concerned that increased use and availability of NIPT intensifies the challenge of providing of up-to-date information about genetic conditions and disabilities to pregnant women undergoing prenatal testing. Others are concerned that wider use and availability of prenatal genetic testing will make life harder for people with genetic conditions and disabilities because, for example, fewer will be born and they may experience more prejudice and discrimination.
In the future, NIPT may allow pregnant women and their partners to test their unborn babies for a wider range of genetic conditions and disabilities including those that develop in adulthood, and to find out about non-medical information relating to behaviour and physical appearance. It is possible that NIPT could be used to carry out what is called ‘whole genome sequencing’, which would reveal the complete genetic make-up of the baby.
Find out more about the terms of reference of this project and what we mean by NIPT.