Put those eggs on ice; most couples without children wait too long to have them; but technology may have an answer.(Cover story)

Byline: Daren Briscoe

The danger of delaying childbearing, of course, is that a woman who eventually wants a baby may be unable to have one because her eggs are no longer viable. But researchers have developed a procedure that, while not stopping a woman's biological clock, can in effect act as a snooze button. Egg freezing, or "oocyte cryopreservation," uses hormones to boost a woman's production of eggs, which are then extracted and frozen, allowing them to be thawed, fertilized and implanted in her womb at a later date. Freezing puts the eggs in a state of suspended animation, meaning that in theory, a woman can keep a viable store of eggs on ice long after her body's natural supply is depleted.

While egg freezing is available primarily to cancer patients facing infertility from chemotherapy and radiation, a growing number of clinics are offering the procedure to otherwise healthy women who simply want to postpone childbearing for personal reasons. Italy, which has laws banning the use of frozen embryos, has been a leader in developing one technique, where extracted eggs are dipped into a solution and then slow-frozen. South Korea has advanced another method, called vitrification, where liquid nitrogen is used to flash-freeze the eggs. Dr. Bradford Kolb of the Huntington Reproductive Center in Pasadena, California, has been providing egg freezing to the general public since 2004. "It's not going to guarantee any future pregnancy, but we're giving women the potential to have children with their own eggs," he says.

The first pregnancies from frozen eggs were reported almost two decades ago, but even today only about 200 babies have been born from them. Some experts worry that the practice is being widely adopted before enough is ...