More needs to be known about the long term health dangers of egg donation, fertility experts have warned.
Overstimulation of the ovaries can be fatal
Increasing demand for fertility treatment and stem cell research means hundreds of thousands of human eggs are being sought worldwide.
Yet relatively little is known about the possible risks, which can be fatal.
Members of the European Parliament will debate on Thursday whether it is ethical to ask women to donate eggs without knowing the risks.
The Brussels conference is being hosted by Comment on Reproductive Ethics.
MEP Katherine Sinnott believes women from vulnerable socio-economic backgrounds are being exploited by being offered financial compensation for their eggs.
"It disingenuous. It's buying eggs," she said.
"It's in clear contravention with European policy. Human parts may not be paid for."
She warned that women were not aware of the risks they were posing to their own health.
Dr Kamal Ahuja, Scientific Director at the Cromwell IVF and Fertility Centre, London, does not disagree with women donating their eggs per se, but he said that until it is clear what the long term health risks are, donor eggs should only be taken from women undergoing IVF treatment.
"We would encourage those who wish to donate eggs for research to consider it seriously. We don't know the long term consequences.
"We are not in a position yet to reassure those women that they are not taking some risks that perhaps we can't guarantee against.
"There must be a distinction between a risk taken to help save a life or help someone overcome illness, and a risk that is completely avoidable.
"There are alternatives. We would encourage people, particularly the policy makers, to look at the idea of egg sharing."
SYMPTOMS OF OHSS
Abdominal discomfort and swelling
Thirst, nausea and vomiting
Egg sharing describes when the surplus eggs produced by a woman undergoing IVF treatment to become pregnant are donated for use by other women, or for research.
Dr Ahuja said there would be enough eggs to go round for both IVF and research using egg sharing alone.
One rare, but potentially fatal, risk of egg donation is ovarian hyperstimulation syndrome (OHSS).
It is caused by the drugs that are used to make the ovaries produce more eggs than normal.
In mild and moderate cases, affecting up to 20% of women undergoing ovary stimulation, this leads to symptoms such as swelling and breathlessness that resolves.
However, in about 1% the symptoms can become so severe that they are deadly.
To date, five women in the UK have died of OHSS.
Alison Murdoch, chairwoman of the British Fertility Society, said although OHSS was serious, it was important to keep the risk in perspective.
"We stimulate something like 40,000 women per year for IVF treatment and there have been five reported deaths in the UK.
"The risks of someone dying during a pregnancy are very much higher than the risks with IVF treatment."
A spokeswoman from the Human Fertilisation and Embryology Authority said: "It is vitally important that patients are informed about the risks of IVF prior to treatment.
"Patients must be told about the risk of severe OHSS and what symptoms to look out for and when to seek help."
She said all HFEA-governed clinics were given guidelines stressing these points.
A LIFE spokesperson said women undergoing IVF treatment were acting as guinea-pigs for the industry.