A fertility clinic could be forced to stop its sperm donation service after new rules denying men the right to anonymity.
A shortage of sperm donations threatens the service
The Cardiff Assisted Reproduction Unit used to have between 17 and 19 sperm donors registered, but now has just two regulars.
Staff at the clinic have blamed new rules which will allow donors to be identified from next April.
They fear the service may have to end unless more volunteers are found.
The donors, who get expenses of £17.50 for every donation they make, are allowed to father only 10 children.
Staff at the clinic, which provides help for childless couples throughout south Wales - both NHS and private patients - are concerned that once the two remaining donors reach their 10-pregnancy limit, there will be noone to replace them.
Staff nurse Lorraine Goacher said sperm banks in the rest of the country were also facing a shortage in donor supplies.
"We have had a lot to do with [sperm banks in] Liverpool and London and the service has practically dried up," she said.
"We have never had any problem buying what we need before, but last month when we rang up they said they supplies were limited."
From April 2005, any man wishing to donate sperm has to be prepared to be identified - in case any future offspring want to trace them.
It also means that a child born as the result of egg donation will be able to track down the genetic mother.
Staff at the clinic, which has been offering the service for 25 years, believe the new rules have put men off.
They are concerned for the couples who are on the 100-strong waiting list whose only chance of conceiving is through the donor insemination programme.
"We may be forced to stop the donor programme," said Ms Goacher. "It is a real threat."
"Some of the people who come here have been through such a lot already, some with major problems like cancer, for example.
"This is a very successful programme - sperm donation is one of the most successful treatments.
"To think that these people are not going to have the chance is very sad," she said.
Elfed Williams of Infertility Network UK, a charity to help childless couples, said: "A lot of couples are waiting to have the treatment and it is heartbreaking that, because of the new rules, their chances of having treatment is diminished.
"I don't think that the government have thought it through properly.
"I think the problem is going to be widespread - Cardiff is not going to be an isolated case.
"We have got a number of couples telephoning us, trying to find out what the situation is going to be, and it is extremely disappointing for them because a lot of them have been waiting a long time," he added.