Rita Ora is one woman who has bucked the trend. The pop singer, 27, had her eggs frozen following a recommendation from her GP. Picture: Axel Schmidt/AP

London - Women who want to delay motherhood have the best chance if they freeze their eggs in their early 20s, experts say.

The vast majority of women who go through the procedure do so in their late 30s – by which time they have very little chance of success.

Specialists are increasingly concerned that fertility clinics encourage women to delay motherhood for too long by offering them the safety net of egg freezing. 

The longer they wait, the lower the chance of being able to start a family – yet two-thirds of women who freeze their eggs do not do so until they are over the age of 35.

The Royal College of Obstetricians and Gynaecologists said women who leave it too late will struggle to have a baby.

Spokesperson Professor Adam Balen, a consultant in reproductive medicine at Leeds Teaching Hospitals, said: "Evidence suggests the best time to freeze eggs is in a woman’s early 20s and certainly under the age of 37 … It is extremely important to provide accurate and balanced information about fertility and how it changes with increasing age."

He said clinics must give women a full picture about their chances of starting a family.

Experts are worried young women do "not feel the threat of infertility" – partly because they are given the false hope of freezing their eggs later. But by the time they get round to it, fertility treatment is a ‘last-ditch’ effort with diminishing chances of success.

Rita Ora is one woman who has bucked the trend. The pop singer, 27, had her eggs frozen following a recommendation from her GP. "I have always wanted a big family and my doctor asked me 'I think you should freeze your eggs' when I was in my early 20s," said Ora, who was born in Kosovo before moving to London when she was one. "He said you are healthiest now, why not put them away and then you never have to worry about it again."

Dr Timothy Bracewell-Milnes from Imperial College London, writing in the British Journal of Obstetrics and Gynaecology with colleagues from Chelsea and Westminster Hospital, said: "Egg freezing is indirectly encouraging women to have children at an advanced maternal age, which carries with it significantly increased risk of medical complications in pregnancy.

"This is especially relevant to women freezing their eggs when they are already in their late 30s."