A Belgian team has raised hopes that women who have treatment for cancer and women who want to delay motherhood until after menopause can still become pregnant naturally. In an article in this week's issue of The Lancet Dr Jacques Donnez outlined how he froze ovarian tissue from Ouarda Touirat when she was 25 in 1997. Six years after treatment for Hodgkin's lymphoma, Ms Touirat was cleared of cancer and had her tissue transplanted. Her ovarian function was restored and she became pregnant naturally.

This new technique is good news for young women with cancer. But it could also enable women to postpone child-bearing until they have established themselves in their careers -- at a time of life when their contemporaries are already grandmothers. However, a British scientist warned that the technique has limitations. Professor David Baird, of Edinburgh University, said the operation would be most useful for women with cancers which could not spread to the transplant graft. "I think it's a terrific advance, but I think it would be very easy to oversell it," he said.