4 September 2015
The rapidly expanding capacity to diagnose serious chromosomal defects via early, safe non-invasive prenatal testing (NIPT) is arguably one of the most exciting medical developments of recent years. Progress has been very fast in the years since the PHG Foundation published the first report to examine the potential health service implications of NIPT in 2009. That report outlined looked forward to the emerging capacity to identify specific recessive genetic disorders and the likely application for trisomy 21 (Down’s Syndrome).
What do women want?
For two or three years following release of that report I would receive emails and phone calls from anxious expectant mothers – and indeed anxious mothers of anxious expectant mothers – who knew or believed their risk of having an affected foetus was high. All were desperate to access non-invasive testing, regardless of the price. At the time, however, there was nothing available; no commercial services had yet launched, even in the US, and use was restricted to small clinical trials with strict recruitment criteria.
Now, of course, there are multiple commercial providers offering NIPT for a widening range of the more common chromosomal abnormalities, including trisomies 13, 18 and 21; sex chromosome aneuploidies; and even sub-chromosomal abnormalities such as Di George Syndrome. The capacity for NIPT to replace serum testing as a first line screening approach has been demonstrated in not only high-risk but also in low-risk pregnant populations.
Ethical issues posed by prenatal testing
This is a very good thing from the perspective of many health professionals and patients, virtually eliminating as it does the dilemma for high-risk women who want to know whether or not their foetus is affected but must choose invasive diagnostic procedures to be sure. The risk of a false-positive result from NIPT is significantly lower than that from serum screening. However, the proliferation of NIPT has also rung ethical alarm bells; the original PHG report on the topic devoted an entire appendix to potential ethical, legal and social obstacles to implementation in health services, including the normalisation of NIPT, failure to obtain properly informed consent to the testing, pressure to accept testing and diagnosis, and pressure to terminate pregnancies following diagnosis of a chromosomal defect.
The danger of technology ‘push’
Now there is also debate over how far commercially driven expansion in NIPT from well-defined and medically significant conditions into the more unpredictable realms of more minor sub-chromosomal defects – the clinical implications of which are much less clear cut – might and should go. Whilst commercial providers can definitely be seen to be providing a valuable service (one that the women who contacted me in the past would have been delighted to pay for), it is also appropriate to question developments that are less obviously driven by patients, and that raise concerns among health professionals.
The danger of legal barriers
A different and perhaps even more worrying development is attempts in the US state of Ohio to legally prohibit access to abortion following prenatal testing. Apparently the state of North Dakota already has a similar law in place, banning abortion on the grounds of foetal genetic abnormalities. If the Ohio bill is passed then there too it will be technically legal to abort a healthy foetus, but not to abort one with genetic abnormalities, which seems nonsensical. Even the mildest of such abnormalities can have profound medical impacts for the affected child, and hence also for their family (and indeed their health service).
Whilst it is important that the provision of prenatal testing options should not dictate or unduly influence the decisions of the pregnant woman - some of whom may prefer to continue the pregnancy, even in the case of devastating abnormalities incompatible with life - the fact remains that the overwhelming majority of women who receive definitive prenatal diagnoses of genetic abnormalities choose to terminate the pregnancy. There is therefore clearly ongoing patient demand for access to termination on medical grounds.
The value of informed choice for patients is widely recognised in medical practice, but genetic counsellor Laura Hercher observes: ‘restrictions on prenatal diagnosis are not empowering’ and warns that they are likely to have a disproportionate impact on poorer and more vulnerable women. Bioethicist Ainsley Newson and colleagues have previously identified three main harms associated with the provision of prenatal diagnostics ‘in the absence of legal and safe abortion’ for the corresponding conditions: psychological distress, financial burdens for families and society, and an unjust distribution of burdens between different socio-economic classes.
Technology offers us great new opportunities to prevent disease and improve health; it is essential that such developments are carefully scrutinised by experts, patients and wider society to ensure that the right balance is struck between potential benefits and possible harms. This is rarely an easy task, given the wide variety of individual opinions and interests involved, most especially on issues of life and death. But it is hard to see how obliging mothers to give birth to babies with known and medically significant genetic abnormalities against their will can be anything other than harmful.