Philadelphia

Research advances that enable women's eggs and ovarian tissue to be frozen for later use in assisted reproduction are not yet suitable for widespread adoption, says a report from the American Society for Reproductive Medicine (ASRM).

The methods “are by no means ready for prime time,” Mark Fritz of the University of North Carolina at Chapel Hill, head of an ASRM committee that advises members on clinical practice, told the society's annual meeting in Philadelphia this week. Fritz said that doctors need to collect far more data on the health of children born through these methods before they become widely used.

A woman's fertility generally declines from puberty onwards, and more steeply from her thirties, as eggs are ovulated, die or deteriorate. Women with cancer and other illnesses can be rendered infertile much earlier if their eggs are damaged by chemotherapy or radiotherapy.

One way round this is to remove and freeze eggs before the treatment, for use later for in vitro fertilization. But doctors are still working out how to reliably prevent formation of damaging ice crystals in the eggs, and there have been fewer than 100 live births through this method. At least two US companies, however, offer women the chance to freeze their oocytes.

Another option still at the experimental stage is to remove and freeze entire slices of ovarian tissue, containing many eggs, and reimplant them later. Last month, doctors in Belgium announced the birth to a former cancer patient of the first baby produced by this technique.

The ASRM report ‘Ovarian tissue and oocyte cryopreservation’, is also published online this month in Fertility and Sterility (82, 993–998; 2004). It agrees that the techniques should be offered under strict supervision to cancer patients or other women who will be rendered infertile by medical treatment and who have few other options if they want children.

Before such techniques are offered to infertile but healthy women, the committee recommends that more data be gathered on any adverse effects on a woman's health or the risk of abnormalities or long-term health problems in her children. “Worldwide experience is simply insufficient at this time,” Fritz says. The ASRM guidelines are not binding, but those in the field say that most US fertility clinics are expected to abide by them.