Career women who want a family are freezing their eggs for later use to remove the pressure to find Mr Right, research shows.
The difficulty of finding a partner to father their children is a key reason why women try to preserve their fertility into their forties, the first study of motives behind egg freezing reveals.
Advances in freezing will revolutionise in vitro fertisation (IVF) by allowing women to store "young" eggs when they are in their twenties and thirties.
Using young eggs in IVF improves the chance of success and reduces the risk to the baby. Experience with the technique has advanced most rapidly in Italy.
In England, the law was changed in 2000 to allow clinics to store eggs by freezing them. Two babies have been born with the technique and 22 clinics are licensed to provide treatment.
Twenty women who chose to have their eggs frozen for social reasons at Reproductive Medicine Associates, an IVF clinic in New York, between July last year and April this year were assessed by psychologists.
All the women were single, with an average age of 38.6, and none had a medical reason, such as radiotherapy for cancer, which would destroy their ovaries, to preserve their eggs.
Results showed half of the women said they felt pressured by their biological clock and 60% wanted to be sure they had taken advantage of "all possible reproductive opportunities". Half said they saw egg freezing as an insurance policy, but would probably never use the eggs.
Four out of 10 said that they would be willing to become a single parent and eight out of 10 said they were either willing or unsure. Although it was late to freeze eggs at 38, the women claimed had they known about the technique earlier they would have used it when they were younger.
The researchers, led by Alan Copperman, who presented their findings to the American Society of Reproductive Medicine in New Orleans this week, said the women were highly educated and overwhelmingly described themselves as "intelligent" and "extroverted".
They added, "A number of women said they were interested in egg freezing to take the pressure off the search for relationships. Cryopreservation meant the freedom to not settle for a mate because they were in a rush to conceive."
Most women who freeze their eggs do so because they have cancer and the treatment could leave them infertile, or they have ethical objections to freezing embryos. But as the technique advances, demand for egg freezing for social reasons is expected to grow.
Gillian Lockwood, director of British Midland Fertility Services, said last month that women in their thirties should think about freezing their eggs. If they found themselves childless a decade on, it would increase their chances of conceiving. Fertility clinics could come under pressure from older women who believed they had a right to have their own stored eggs fertilised and replaced in the womb later, she said.
But freezing eggs for social reasons was criticised by Francoise Shenfield, consultant gynaecologist at University College Hospital London and an expert in medical law and ethics.
"I feel it is the wrong way to think about becoming a parent. It is never going to be convenient. All career people face the same problem and they need to think about it in their early thirties.
"People have to be reminded that they have to make compromises between children and career. It is not only a medical problem, it is a political one." - Tribune Foreign Service