By Helen Briggs BBC News

Pregnancy, but at what cost?

British couples are turning to the internet for information on where to get fertility treatment abroad.

In the absence of official advice, patients are using message boards on support websites such as Fertility Friends to select clinics.

According to Guido Pennings, of Ghent University, Belgium, the web is a key factor in the boom in IVF tourism.

But he said patients should be aware of ethical issues, amid concern over how some clinics are recruiting donors.

The Professor of Ethics and Bioethics in the Department of Philosophy and Moral Science said there was "anecdotal evidence" that some clinics, particularly in Eastern Europe, were exploiting donors.

"They recruit even illiterate people who don't know what they are going in for - clearly a violation of informed consent," he said.

He warned that information on such things as success rates published on websites might not be reliable.

"There is no organisational state or department that is able to verify the information they provide," he told the BBC News website.

UK rules

In the UK, donors cannot be paid for donating eggs or sperm but may claim for "all reasonable expenses" including travel, accommodation and childcare costs.

It's not just giving a few body cells because if the treatment is successful those will grow up into children Dr Eric Blyth, British Association of Social Workers

However, women are able to get subsidised IVF treatment, in exchange for donating eggs to other couples, or, in the case of one fertility centre in the north east, for research.

Different rules apply worldwide. Women are paid around �420 in Cyprus for their eggs but in the US figures range from �5,000 to �30,000.

Eric Blyth, Professor of Social work at the University of Huddersfield, UK, said young women may be "lured by what appear to be very large sums of money for what is being presented as a minor medical procedure".

He said anyone considering going abroad for donor eggs should consider the impact on any future children.

"It's not just giving a few body cells because if the treatment is successful those will grow up into children," he told the BBC News website.

"At the end of it all you have to make the decision whether it is right for you, whether you can live with the consequences.

"If this procedure results in what you want - a child - you have to think of their interests."

'Forgotten numbers'

But ivfworld.com, a network for fertility patients, said this was not an issue for most women with fertility problems, since only a minority were choosing to go abroad for treatment.

The issue really is ageism and sexism in the NHS; a whole generation of women have been caught in the trap Spokesperson, ivfworld.com

"Some people are going abroad but a lot of are choosing not to go down that route; they are the forgotten numbers," said a spokesperson.

The main problem, the spokesperson added, was that women who had delayed childbirth for social reasons were not eligible for fertility treatment on the NHS because of their age.

"The issue really is ageism and sexism in the NHS; a whole generation of women have been caught in the trap," the spokesperson said.

"It's treated like a dirty little secret, but for women with infertility, it's like suffering from cancer - a lot of feelings they have are akin to suffering from an illness."