File photo: Only about one third needed IVF. Picture:

London - Women should freeze their ovaries rather than their eggs to protect their fertility, experts are advising.

More than a third of women who freeze ovarian tissue go on to have a baby, a study shows.

Its authors say ovary freezing, only currently available in Britain for medical reasons, should now be looked at for healthy women too.

Almost 4 000 women, who are afraid of running out of time to have a baby, have opted for egg freezing.

It involves returning to a clinic for IVF, and those who are past the age of menopause need hormone replacement therapy to have a child with their own eggs.

Freezing ovarian tissue goes much further by offering older women the chance to turn back the clock, reverse their menopause and conceive naturally without fertility treatment.

The study by New York Medical College found almost 38 percent of women had a baby after ovarian freezing. Co-author Dr Fernanda Pacheco said: "The procedure is superior to egg freezing as it can also reverse menopause and restore natural fertility.

"The next frontier is to explore the procedure’s potential in delaying childbearing among healthy women."

US researchers examined every case of ovarian tissue freezing between 1999 and October last year.

Women up to the age of 40 gave birth to 84 children after 309 freezing procedures, with eight having more than one child using frozen ovarian tissue.

Almost two out of three women were able to reverse their menopause or restore their reproductive function. Close to two-thirds were able to conceive naturally.

Only about one third needed IVF. This is because frozen ovarian tissue contains immature eggs, which grow into mature eggs when it is placed in a woman’s body. Ovarian tissue was kept on average for just over two years in the cases analysed.

Responding to the findings Dr Melanie Davies, at London’s University College Hospital, said the long-term outcomes of tissue freezing "are still not known" while egg freezing is "proven".

"Ovarian tissue freezing is not science fiction but it is a long way off for non-medical reasons in Britain," she added.

"Women considering freezing need to be well-informed so they can make informed decisions for themselves."