Egg sharing is where a woman donates her eggs for use in in-vitro fertilisation (IVF) in return for the same treatment.

The authority had been considering a ban following a case where one of the women involved got pregnant while the other did not.

Instead of a ban, the authority will prepare specific guidelines in its next code of practice.

Thursday's announcement added that payments to sperm and egg donors would be allowed to continue for the foreseeable future.

The authority, which regulates the use of reproductive material, had previously said it would like to see an end to such payments.

Donor practice

At the moment, donors can be paid up to �15 as "expenses". Most sperm donors are students, and in particular medical students.

Pregnacy is not always guaranteed

Recently there has been a shortage of donors, and it was reported that in one case a hospital in Scotland had to import sperm from Scandinavia.

Part of the reason is that some donors fear they may in the future be sought out by any children conceived with their sperm.

But donors are currently guaranteed anonymity and the HFEA says there is no possibility of retrospective identification in the future.

Ruth Deech is chairman of the HFEA. She said: "The HFEA believes that the donation of sperm or eggs to create new life should be a gift freely and voluntarily given."

However, she added: "It has become clear that the removal of payments in the present climate would seriously jeopardise the supply of sperm donors."

Complexities

Mrs Deech said that egg sharing presents more complex problems.

"While no-one can have a problem with a woman who is undergoing IVF freely and voluntarily choosing to share surplus eggs with someone else, we recognise the concerns arising when subsidised IVF treatment is offered for such eggs.

"The overwhelming view of the HFEA was that it would not be right to ban paid egg sharing, which can be hugely beneficial to both sharer and receiver."

The authority would continue to examine the issue, she said and will draw up a code of practice.

Professor Ian Craft, director of the London Fertility Centre said the HFEA had made the wrong decision in maintaining the status quo.

"They seem to have moved their own goalposts," he said.

"From wanting to cease all payments altogether they seem to be moving back towards the middle ground and saying 'well, it is difficult to recruit donors and if we actually cut off the payments, especially to sperm donors, there will be no donors,' which is probably true."

'Wrong way round'

Professor Craft said that he did not agree with the continuation of egg sharing.

IVF clincs need more donors

"I don't agree that infertile women should give their eggs to infertile women, I think that's the wrong way round," he said.

"We need to be much more radical - how do you find more egg donors? How do you get more sperm donors?"

He suggested that increasing the payments would be one way to encourage donations.

He suggested raising the payment for sperm donations to �25 and for egg donations up to �500 to cover all expenses.

Complex donation

This is because egg donations are significantly more complicated than sperm donations. Women who donate first take a 12- to 14-day course of injections to stimulate egg production before undergoing a 40-minute procedure to collect the eggs.

Professor Craft said fertility treatment should be regarded as a more mainstream part of medicine.

"You can make magic happen . . . it would be wonderful if more donors would come forward."