New pregnancy testing technique needs limits says ethics body
A new report on non-invasive prenatal testing (NIPT) by the UK's Nuffield Council on Bioethics expresses concerns about the way the test is being sold by private providers. In addition, the Council calls for better information and support; calls for a moratorium on the use of NIPT in sequencing the whole genome of fetuses; and calls for a ban on its use in finding out the sex of the fetus.
NIPT is a major breakthrough in prenatal screening and testing for a range of genetic conditions. It uses a blood sample taken from the pregnant woman and can be done from 9 or 10 weeks of pregnancy. It analyses DNA from the placenta that circulates in the woman's blood to estimate the chance that the fetus has Down's, Edwards' or Patau's syndromes. It can also be used to diagnose other genetic conditions, such as cystic fibrosis and achondroplasia; or to determine the sex of the fetus.
The test is currently available in the UK through private hospitals and clinics, and in some NHS hospitals. Last year, the UK Government announced that from 2018, the NHS will offer NIPT to pregnant women who have been found through initial screening to have at least a 1 in 150 likelihood of having a fetus with Down's, Patau's or Edwards' syndromes. Its introduction should mean fewer false results and fewer diagnostic tests, which carry a small risk of miscarriage. The use of NIPT for testing for Down's syndrome attracted considerable media attention last year.
The Council considered, at this early stage of its use, how NIPT could change the way we view pregnancy, disability and difference, and what the wider consequences of its increasing use might be.
The report recommends that NIPT should only be used for significant medical conditions and impairments that affect the child at birth or in early life as this information can allow women and couples to make meaningful reproductive choices.
The Council says it should not normally be used for less significant medical conditions and impairments, for those that appear in later life, or for non-medical traits (such as sex). Information on all of these kinds of genetic features, and more, could be obtained if NIPT was used to sequence the whole genome of the fetus. The Council therefore calls for a moratorium in the use of NIPT for whole genome sequencing and a ban on its use in finding out the sex of the fetus.
The key reasons for these restrictions are:
- – The current uncertainty about the significance of many genetic changes
– The lack of medical benefit to knowing about many genetic changes
– The risk the mother may have a termination, or become unduly anxious, because of this early information
– The right of a future child to find out their own genome for themselves
Professor Tom Shakespeare, Chair of the Nuffield Council's Working Group on NIPT and Professor of Disability Research at the University of East Anglia said: "We support the introduction of this test for Down's syndrome on the NHS next year, so long as it is accompanied by good balanced information and support. But, if the test is used without limits for other kinds of genetic conditions and traits, it could lead to more anxiety, more invasive diagnostic tests, and could change what we think of as a 'healthy' or 'normal' baby. We therefore think the test should generally be used only for significant medical conditions that would affect a baby at birth or in childhood."
He added: "That's why we are calling for a moratorium on its use in sequencing the whole genome of the fetus. We also strongly believe there should be a ban on its use to find out the sex of the fetus, as this could lead to sex-selective abortions."
In considering the question of attitudes to disability, he said: "If women and couples are to make a truly free decision, they have to be confident that they will be supported equally in whatever choice they make, and if they do go ahead and have a disabled child, that society will support them and their family in future."
Dr Louise Bryant, member of the Council's Working Group on NIPT and Associate Professor in Medical Psychology at the University of Leeds, said: "Although we heard of examples of good practice, the information currently provided to women and couples by the private sector is frequently incomplete, unsubstantiated, inaccurate or misleading, and sometimes uses emotive language."
She cautioned that women and couples need to understand the limitations as well as the benefits of NIPT, especially when used to test for conditions other than Down's syndrome: "We are concerned that some private providers may give out information that emphasises the accuracy of the test but does not make clear its limitations. We are concerned that some women are not being supported well enough to make informed decisions, and that some private services may be failing to provide adequate aftercare for those with positive NIPT results.
"Parents should also be provided with an up-to-date picture of what life is like for people with the condition. The impact of Down's syndrome for example varies from person to person. In some cases it can have minor effects on people's lives, whilst in others the effects are more significant. Women and couples must get balanced information and support to help them make decisions that are right for them".
Notes to Editors:
- – The report is the outcome of a project carried out by an interdisciplinary Working Group that included expertise in genetic counselling and clinical medicine, disability issues, public health, psychology, law, philosophy and ethics. In coming to its conclusions, the Working Group considered the views of a wide range of people, such as doctors and midwives, women who have had screening, and people with genetic conditions and variations, such as cystic fibrosis and Down's syndrome, and their families.
– From 2018, NIPT will be offered to women as a 'second stage test', after the combined (blood and ultrasound) test. Currently women who are found to have a high chance of their fetuses having one of the syndromes following the combined test are offered a diagnostic test (CVS or amniocentesis, both of which are invasive). From 2018 the offer would take place in the following sequence: the combined test, NIPT, followed by a confirmatory (invasive) diagnostic test.
Key facts and figures from the UK
- – The chance of a woman having a fetus with Downs is about 1 in 1000 but that increases with age.
– Around three quarters (74%) of women currently decide to have a screening test for Down's – a figure that varies across the UK.
– Around 1 in 200 (0.5%) of invasive tests (amniocentesis and CVS) result in miscarriage – although this figure is contested.
Improvements in screening methods have led to an increase in the number of prenatal diagnoses of Down's syndrome over the past 25 years. For example, in 1989, 320 fetuses were diagnosed with Down's syndrome, and in 2012, there were around 1250 diagnoses. (During this period the number of live births in England and Wales fluctuated between approximately 570,000 and 720,000 per year.)
The proportion of women having a termination after a diagnosis ranged from 89 to 95 per cent between 1989 and 2012, meaning that the actual number of terminations has increased. However, the number of live births of babies with Down's syndrome has remained fairly constant during this period with around 700 babies born each year. This is likely due to an increased incidence of Down's syndrome in fetuses caused by an increase in the average age of mothers.
Studies have suggested that when NIPT is offered to pregnant women with at least a 1 in 150 chance of having a fetus with Down's it would lead to:
- – nearly 200 more fetuses with Down's syndrome being identified per year
– around 3000 fewer invasive tests,
– an estimated 17 fewer procedure-related miscarriages
The likelihood of a false positive result in women already found to have a higher chance (>1/150) of having a Down's syndrome fetus is 1 in 10. When NIPT is used in any pregnant woman it is 2 in 10.