Ruth Deech tells the BBC's Today programme about egg-sharing

The women had been trying to have a test-tube baby and had agreed to share her eggs in order to have a free attempt at in-vitro fertilisation.

Each attempt costs up to £3,000.

The Human Fertilisation and Embryology Authority (HFEA) is to discuss a ban on egg-sharing on Thursday in the light of the case.

A spokesperson said the donor had become very upset when she did not become pregnant after finding out by accident that the other woman's treatment had been successful.

"The chances are that once some women are given an egg, they will become pregnant whereas the donor can produce eggs, but has something else wrong with them. It can be very distressing," he said.

Vulnerable

IVF has a low success rate - around 15% and only around 18% of it is funded by the NHS.

The HFEA wants to protect vulnerable women from being exploited because they cannot afford IVF treatment.

It would prefer to increase the number of egg donors, but to remove the financial incentive for donating.

"The practice could be described as paying women a few thousand pounds for their eggs," Ruth Deech, chairman of the HFEA, told the BBC's Today programme.

She added that women needed protection from financial inducement.

However, five fertility doctors sent a letter to the Sunday Times said banning egg-sharing could mean fewer eggs for IVF treatment.

"The cornerstone of HFEA policy appears to be to make more women aware of the need for egg donors.

"We believe this is naive, socially coercive, unproductive and by omission of any reference to risk, brutally misleading," says the letter, signed by leading doctors including Professor Robert Edwards of Cambridge University.