Scientists are working towards gene transplant surgery on unborn children.
The treatment is already given to children
Researchers at Imperial College and University College, London have already successfully implanted corrective genes in foetal mice.
They now hope to use the technique on human foetuses, and say it could help cure inherited diseases such as haemophilia.
The Gene Therapy Advisory Committee would have to give its approval before the research could go ahead.
Researchers used a human immunodeficiency virus (HIV) as a vector to transfer the corrective genes into the recipient, having first removed the disease-causing elements of the virus.
This allows the "good" gene to get into the nucleus where it can correct genetic conditions.
The researchers are hopeful the technique could be used in unborn children who are at risk of developing other inherited conditions such as cystic fibrosis and sickle cell disease. They are concentrating on severe metabolic diseases.
Gene therapy in children and adults has faced problems because an immune response can be created by the recipient's body. Antibodies produced can prevent the treatment working.
The hope is that, at the foetal stage, the immune system is not yet developed sufficiently to prevent the effect of the implanted genes.
Professor Charles Rodeck, professor of obstetrics and foetal medicine at University College, said: "We have some hope and optimism that at some point in the future this will be a useful form of treatment.
"It seems to be working well in the mouse, but we can't jump from mouse to human. We have to work it out in a larger animal model."
Work is now under way to start research on sheep and the aim is then to move onto humans.
People who have tests in pregnancy confirming their unborn child has a genetic condition currently only have the option of terminating the pregnancy or continuing anyway.
Professor Rodeck said: "We would like this to be a third option - perhaps the best option."
Professor Charles Coutelle, at Imperial College, said: "We would like another five years to make decisions about which diseases and which vector to choose, so we can do all the necessary safety tests we and the regulatory bodies think are required."
A spokesman for the Department of Health, under which the Gene Therapy Advisory Committee operates, said the researchers would need the permission of the committee and the Medicines and Healthcare products Regulatory Agency before testing on human foetuses.
The committee has previously said it is too early to run tests on humans and experiments should be limited to animals.
The Cystic Fibrosis Trust said: "We welcome any development in cystic fibrosis research but we don't expect any of these developments to be available in the near future."