The prospect of women routinely freezing unfertilised eggs for IVF has moved a step closer after research.
Fertility treatment has tended to rely on freezing embryos
Thirteen children were born after 68 couples underwent treatment by Italian doctors who froze unfertilised eggs.
Egg freezing is not new but doctors have struggled to achieve live births and tend to rely on freezing embryos as eggs are more vulnerable.
The team from Bologna's Tecnobios Procreazione now wants to improve the number of eggs which survive freezing.
The team froze 737 unfertilized eggs using the same method of slow freezing used during the cold storage of embryos.
But only 37% of the eggs survived the process of freezing and thawing as unfertilized eggs are vulnerable to ice formation.
The team said it was hoping to achieve a 75% to 85% survival rate by modifying the egg by increasing the concentration of sucrose, which lowers the water content and reduces the risk of ice forming.
However, this process does make the eggs susceptible to "dehydration stress" during the thawing process.
The findings appear in the medical journal Fertility and Sterility.
Unfertilised eggs have been frozen during fertility treatment before - the first pregnancy happened as long ago as 1986 - but the high number of births achieved by the Italian team has given them hope a major breakthrough is only a few years away.
But Dr Giovanni Coticchio, research supervisor at Tecnobios Procreazione, said the 37% survival rate was not enough.
He said he believed the freezing of eggs had the potential to revolutionise IVF treatment.
"Women could have much more control of fertility treatment.
"They could store their eggs at a younger age, which then means the chances of a successful pregnancy increase because the quality of the eggs reflects the mother's age.
"It also gives women the same opportunities as men who have their sperm frozen."
The treatment could be used for women who were at risk of losing ovaries during cancer treatment.
But it also opens up the possibility that women could have eggs frozen before they even meet a partner.
Such treatment would not be allowed in Italy under strict fertility laws but some countries, including the UK, would allow it.
The Centres for Assisted Reproduction (CARE) group of fertility clinics does store some frozen eggs for women for medical reasons.
Care managing director Dr Simon Fishel said the problem with egg freezing was that it was costly, inefficient and uncomfortable for the patients.
"Freezing eggs is still at the experimental stage so women have tended to use it only if they are undergoing medical treatment.
"But if the technique improves they may well start to choose it because of lifestyle reasons.
"The [Italian] team are using well-known techniques by tweaking the sucrose concentration but the tweaking may lead to a breakthrough."
Dr Mohammed Taranissi, the director of the Assisted Reproduction and Gynaecology Centre in London, said : "A lot of people have been looking at this. We need to perfect the technology but over time it could certainly become possible."
He also said any developments could also have implications for research as well as fertility treatment.
"If you have a huge pool of good quality eggs it can also benefit research, including stem cell research."