PRE-NATAL screening for Down's syndrome is far from perfect, say health psychologists from a London medical school who are studying how best to convey that message to expectant mums.
Researchers at the United Medical and Dental School's psychology and genetics research group say that maternal chromosomal abnormality tests, which are now offered to most pregnant women, only pick up about 60 per cent of Down's babies.
How best to express this degree of doubt to parents is being examined. Psychologists compared 70 women with negative tests. They told half that they had a low risk of a Down's baby, while also expressing the risk statistically, as a percentage chance, to the other half.
After two weeks, when asked, both groups of parents said they had a low risk of a Down's child. But after four months, those who were not given a numerical result, were instead expressing "no risk". Those who had been given a statistical likelihood still maintained the concept of some risk.
Susan Michie, senior research fellow, said: "How people are told is really quite an important issue, particularly for the small number of women who go on to have problems. We are trying to get the empirical evidence to inform the discussion and the policy decisions which are then made."
A test result showing low risk followed by a Down's baby can lead to problems such as blame, and can affect adjustment to parenting. An initial study has been undertaken involving 29 families with Down's syndrome children. A third had not been offered pre-natal tests, a third had refused them and the rest had had tests that had showed a low risk.
The study is now being increased to 250 families. Initial results suggest that those with a negative test result were more likely to blame the medical profession and were also more likely to experience parenting stress.
"As technology increases so does its clinical applications, but these should be informed both by ethical concerns and by empirical evidence about the social and psychological implications of those applications."