Free foetal DNA testing can be done ethically provided the right conditions are in place. Pregnant women must receive high-quality information and the optional nature of testing must also be reinforced.

One reason that women refuse tests is the risk of miscarriage. If this is removed, the justification will also disappear and women may feel less able to decline.

The result could lead women to a decision about additional invasive tests or termination of pregnancy.

Women should ask themselves what they might do if Down’s were detected: if the answer is “nothing”, then it may be better not to test. If offered to all pregnant women, this type of testing could lead to an increase in abortions.

Down’s syndrome is no longer a fatal disease – it has a wide spectrum of physical and cognitive presentations.

The difficulty is that the degree of impairment cannot be predicted by any test during pregnancy and a complex decision must be made quickly.

We must also face the inevitable question of whether this testing puts us on a path towards eugenics – literally meaning ‘well born’.

But this test is no different to any other in pregnancy: no one will force a woman to have it and there is no state-imposed ideal of perfection. Nevertheless, disability rights activists have a point when they argue that it is hard to select against a baby with Down’s without selecting against Down’s as well.

We need to remember that testing in pregnancy can never guarantee a healthy baby. But for many women the ability to exercise a considered choice is important and this must be protected. Dr Newson lectures in biomedical ethics at the University of Bristol

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