New tests for genetic screening of unborn babies will not be 100 per cent accurate and may scare parents into believing their children will be born with a disability when they are healthy, Lord Robert Winston warns.
American experts have developed a blood test which they claim could be used to routinely screen foetuses for more than 3,000 genetic conditions such as cystic fibrosis and muscular dystrophy.
But the researchers recognised that the ability to predict the genetic code of a foetus at just 18 weeks could raise "many ethical questions" because of the likelihood it would lead to more abortions.
Now some British experts have cautioned that the test – which is still many years from being used in clinics – may do more harm than good because in many cases it would be very hard to predict how a mutation would affect a child and how severe their disability might be.
Others argued that any information which parents can be given to help them prepare for a possible eventuality after their child is born, or to decide to terminate their pregnancy, should not be withheld.
Lord Winston, the fertility expert, said that examining a child's entire genome was ethically no different to current tests for conditions like cystic fibrosis which doctors routinely carry out in families with a history of the disorder.
But he added that screening more widely across the population for thousands of very rare conditions which are not so well understood would make little difference.
He said: "The biggest ethical issue might be that we are going to cause a great deal of worry unnecessarily to a great deal of women who are pregnant. I am uneasy about it because I think it is unlikely to be absolutely accurate and we may raise more concerns in parents than are justified.
"I am fundamentally uneasy about all screening tests. I think that most of the time we are diagnosing things that really are not there and screening like this is probably going to be something where we are going to harm more people than we can help. I am a bit sceptical that it is going to be of value."
Prof John Harris, director of the Institute for Science, Ethics and Innovation at the University of Manchester, said parents should have the right to know if their unborn child was at risk of a genetic abnormality, provided they were given accurate and practical information on the likelihood of it occurring and the possible severity of the condition.
He said: "I believe one should be in favour of would-be parents getting the maximum information about the child that they might be having, either to prepare for eventualities they may face or to take the decision, if it is early enough, not to continue with the pregnancy.
"No potential being has a right to become an actual being – abortion is not a “wrong” to the individual because the individual in question will never have existed.
"We would be negligent and reckless if we paid no attention to the health care of future generations and future people. The ability to protect future generations from terrible conditions that will blight their lives seems to me to be an absolute moral responsibility and a duty that we should not shirk."
Dr Robin Lovell-Badge, head of developmental genetics at the MRC National Institute for Medical Research, said: "While we know the role of many genes and understand how certain mutations can affect the function of some of these in a way that leads to disease, we are still only scratching the surface when it comes to understanding the complexity of the genome.
"So while it is very impressive to be able to predict the genetic code of a developing embryo, in the vast majority of cases we will still be unable to predict how the child will turn out and the nature and severity of any genetic disease he or she may carry.
"We will gradually improve the predictive power of genome sequences, but this is a massive undertaking that will take many scientists many years before we can have any certainty."