Her decision to use controversial genetic-screening technology will ensure that she does not pass on to her child the hereditary form of eye cancer from which she suffers.

Although they did not have fertility problems, the woman and her partner created embryos by IVF. This allowed doctors to remove a cell and test it for the cancer gene, so only unaffected embryos were transferred to her womb.

The couple are the first to take advantage of a relaxation in the rules governing embryo screening.

When the technique was developed in 1989 it was allowed only for genes that always cause disease, such as those for cystic fibrosis. However, it was approved last year for the eye cancer, which affects only 90 per cent of those who inherit a mutated gene.

The pregnancy will increase controversy over the procedure, which the Government’s fertility watchdog authorised on Wednesday for genes that confer an 80 per cent lifetime risk of breast and bowel cancer.

Critics argue that the action is unethical because it involves the destruction of some embryos that would never contract these illnesses if they were allowed to develop into children. Even those that would potentially become ill could expect many years of healthy life first, and some of the disorders involved are treatable or preventable.

The mother-to-be, who wishes to remain anonymous, conceived after receiving treatment from Paul Serhal, of University College Hospital, London.

Mr Serhal has pioneered the use of pre-implantation genetic diagnosis (PGD) to detect heritable cancers in Britain, though it has been used successfully before in the United States. The Human Fertilisation and Embryology Authority’s (HFEA) decision to award him licences to screen for retinoblastoma and a form of bowel cancer were reported exclusively in The Times. Mr Serhal is treating several couples with the disorder.

“We are all elated,” he said yesterday. “We are talking about annihilating this abnormal gene from the whole family line. We do this often, but it is always extraordinary when it comes off.”

Mr Serhal’s clinic is planning to apply to screen a patient’s embryos for the BRCA1 gene that raises the lifetime risk of breast cancer to 80 per cent.

Though the HFEA has now agreed in principle that such screening will be allowed, clinics must still obtain a separate licence for every patient.

Retinoblastoma accounts for 11 per cent of all cancers that develop in the first year of life. In almost half of cases, it is caused by an inherited mutation in a gene called RB1. Parents with this defective gene have a 50 per cent chance of passing it on to a child, and it causes tumours in 90 per cent of those who inherit it. The mutation also raises the lifetime risk of suffering other cancers from a third to more than half.

Libby Halford, chief executive of the Childhood Eye Cancer Trust, a retinoblastoma charity, welcomed the news. “This gives families a choice,” she said. “We know now that there is an effective test.”

Josephine Quintavalle, of the embryo rights group Comment on Reproductive Ethics, said: “We mustn’t forget the embryos that were not given a chance to live. This is a worrying application because we are looking at a condition that is treatable.”

Beating eye cancer

The eye cancer retinoblastoma, seen above in a young boy, affects about 1 in 15,000 children. About half the cases are hereditary, and those who inherit the defective gene have a 90 per cent chance of developing cancer. Up to 95 per cent of tumours detected early can be treated, but this requires chemotherapy and surgery that can cause blindness. A scan in early pregnancy, the stage that the embryo pictured at the top of this article has reached, has confirmed that a woman is carrying Britain’s first child to have been screened for an inherited cancer

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