SINGLE women who want a family one day are being warned not to leave it too late to freeze their eggs.
Researchers in New York found the average age of women seeking egg freezing for social reasons is between 37 and 39 - an age when eggs are rapidly deteriorating.
Evidence suggests women in the UK are of a similar age when they explore egg freezing for lifestyle reasons.
A new analysis of 26 studies also found women under 30 had far more success with frozen eggs than those who were older.
Fertility swiftly declines after the age of 35. In the UK, the success rate of a live birth for each IVF cycle falls to about 5pc for women over 42, compared to about 30% for a woman under 35.
Roger Lobo, president of the American Society for Reproductive Medicine (ASRM), said the new evidence, which is being presented at the ASRM conference in Orlando, showed the importance of not delaying motherhood.
He said: "ASRM considers elective egg freezing an experimental procedure with insufficient data on usage and outcomes to assure patients that it's a worthwhile undertaking.
"Despite increasing numbers of clinics offering the procedure and the significant media attention paid to it in recent years, women are not pursuing elective egg freezing at an age when it would be most likely to help them accomplish their fertility goals.
"It is apparent that patients need more education about their fertility at younger ages."
But Dr Gillian Lockwood, medical director of Midland Fertility Services in Aldridge, near Birmingham, said the ASRM had long been anti-egg freezing for social reasons.
"They are right that egg freezing is not an option for many women in their late 30s when they've discovered Mr Right has turned out to be Mr Wrong, because it possibly is too late," she said.
"But we have to ask what the comparator is here.
"The comparator is how well will these women do with their own eggs in their early 40s?
"A 39-year-old frozen egg is going to do better in IVF than a 42-year-old fresh egg, because the drop off becomes so sharp during these years."
Dr Lockwood frequently sees women in their mid to late-30s who wish to freeze their eggs.
"Unfortunately, 37 is the cusp when the chances go from more or less okay to really not good," she said.
However, factors such as whether a woman smokes do have an impact.
"The women I see who are freezing for social reasons, their stories are very similar," she added.
"They have been in the same relationship since their late 20s/early 30s with a man they thought was going to be the father of their child.
"The woman gets to 36 or 37 and says 'I think it's about time we had a child' and he says he's not ready to settle down yet."
She said these women were then faced with a terrible dilemma - stay and hope the man changes his mind or leave and start again.
These women then sometimes turned to egg freezing.
Dr Lockwood said these women were "deliberately and quite bravely trying to buy a bit of biological time.
"Nobody wants to have desperate tattooed across their forehead but for a 37-year-old woman who wants to have a baby, that's the position she finds herself in.
"These are not crazy Alpha females who want to be chairman of the board and then think about a baby.
"These are women who always wanted to be a mother but it just hasn't happened."
Dr Lockwood has seen around 100 women in the last few years who want to freeze for social reasons.
"With most of the women I see we agree that social egg freezing is not appropriate, either because they've left it too late or because their ovarian reserve is too low.
"I see it as unethical if you are only going to get three or four eggs because really you need 16, 18, 20 to have a realistic chance of achieving pregnancy.
"I would still say a woman up to her mid-30s who wishes to be a genetic mother one day and has not met Mr Right would be much better freezing her eggs than hoping Mr Right turns up before she's 40.
"It's not just getting pregnant in your late 30s and early 40s, it's staying pregnant.
"Freezing an egg freezes the chance of miscarriage.
"To say it's only worth doing if you're in your 20s is wrong.
"This is worth doing in your mid-30s, absolutely, if you know that being a genetic mother is part of your life plan."
The US study on average age for egg freezing was carried out by Reproductive Medicine Associates of New York.
It involved 241 women questioned between 2005 and January this year.