The mother's embryos were screened to remove an inherited gene from her husband, whose sister, mother, grandmother and cousin were all stricken with breast cancer, The Sunday Times of London reported.

The pregnant woman had produced 11 embryos, of which five were found to be free from the gene. Two were implanted in the 27-year-old woman's womb.

The screening of embryos carrying the cancer-causing gene, called BRCA-1, means the London couple will eliminate the hereditary disease from their lineage.

Doctors say thousands of cases of breast cancer could be avoided by pre-implantation diagnosis of embryos.

An Israeli mother-to-be is thought to be the only other woman in the world to have become pregnant after undergoing the embryo screening, The Times said.