by Moira Holden
A shortage of sperm donors has led to calls from fertility experts to change the rules surrounding donation.
Doctors say there is a crisis in infertility treatment caused by the lifting of the ban on anonymity in 2005.
Current rules allow a sperm donor to father children with no more than 10 different women.
But experts want the Government to review this figure because fewer donors are now coming forward.
Around 4,000 patients seek donor sperm each year, so the British Fertility Society reckons 500 new donors are needed each year because not all will agree to the 10-children figure.
But only 307 new registrations were made in 2006. Some clinics have been forced to stop their fertility programmes.
Dr Allan Pacey, secretary of the British Fertility Society, said: 'Many clinics have really struggled over the past few years to recruit enough donors to treat their patients and this has caused a lot of anguish amongst both patients and professionals alike.'
The current limits on allowing a sperm donor to father 10 children should be scrapped, claims the society.
The limit is in place to reduce the risk of donor-conceived children meeting in later life, having an incestuous relationship and children.
But other countries have different stipulations. In the Netherlands, which has a quarter of the population of Britain, the limit is 25.
Writing in the British Medical Journal, Dr Pacey warned there was a 'critical shortage' of donated sperm.
'The current limit of 10 families is arbitrary and not evidence-based, and a large safety margin probably exists, given the size of the UK population and dispersal patterns,' he said.
'A more flexible approach that allows donors and recipients to determine their preference on family numbers could be facilitated.'
Walter Merricks, from the Donor Conception Network, told BBC Online News that reform was needed.
'The current shortage means that many of those seeking donor insemination treatment are going to clinics overseas.
'The vast majority of our members would far prefer to be treated locally with a UK donor under the protections afforded by Human Fertilisation and Embryology Authority (HFEA) regulation.'
