Thousands of couples who seek treatment for infertility pay high prices for low success rates because they do not understand they are operating in a commercial market, a leading American professor has said.

Tough new controls on the £500m baby business in the UK are necessary to prevent the exploitation of would-be parents who are too desperate to consider the cost of treatment, Professor Debora Spar, of Harvard Business School, said yesterday.

In-vitro fertilisation (IVF) costs £3,000 to £5,000 per cycle in the private sector and has a 20-30 per cent success rate, but few couples inquire what the cost is or how many cycles they are likely to need in advance, leaving them facing huge bills for treatment that may not work.

In the US, the average cost of a cycle of treatment is $12,400 (about £7,000), but the average cost of a baby obtained through IVF is $58,000 - something prospective parents are not told before they sign up for treatment.

Professor Spar, who has spent five years researching the fertility industry in the US, will tell the annual meeting of the Human Fertilisation and Embryology Authority (HFEA) today that unless tighter commercial regulation is introduced, Britain will go the way of the US and fertility treatment will become the preserve of the rich.

"There is a market for babies which people don't like to acknowledge. Doctors see themselves as building families and parents see themselves as conceiving a child, not purchasing one. Price is not mentioned, parents have treatment that doesn't work, they try again, it doesn't work again and they end up paying large sums they didn't expect to because no one acknowledged it was a commercial market," she said.

One in seven couples is infertile, but the availability of IVF on the NHS is limited and 80 per cent of treatment in the UK is provided privately. However, there is no requirement on clinics to tell patients in advance what the costs of treatment are or the chances of success.

The Government is currently reviewing the law and Professor Spar said that providing detailed financial information with likely costs for patients of differing ages and with differing problems was essential. A woman of 26 with blocked fallopian tubes was easier - and therefore cheaper - to treat than a woman of 42 with hormonal problems.

"We need to make more information available so consumers have a better sense of what the price will be. People need to know up front what the success rates are and what the final price of a baby is likely to be," she said.

Without commercial regulation, prices would continue to rise and fertility treatment could end up as a luxury service "like the high-end jewellery market", Professor Spar argued. At the same time, doctors could find themselves compromised by patients who demanded they continue with treatment even though it was useless.

"There is an inherent conflict for doctors, who may be forced in to a position where they don't have anything to stop them providing treatment over and over regardless of the chance of success. To protect themselves, patients need to see this as a commercial transaction and they will wind up in a better place emotionally," she said. Lack of information and lack of equity were the two chief problems, Professor Spar added.

The HFEA currently provides only ethical regulation of the clinics. A spokesman said that commercial regulation was not on the horizon. "We have said we want to see clearer financial information given to patients, which is the first step along that road. But on price in the UK, it is a matter for the Government to decide. We are in the middle of a review of the Act and the consultation on the review has not addressed the market aspect of IVF," he said.