Fertility experts say a critical shortage in the number of sperm donations is forcing IVF clinics to advertise.

"You've got millions: we only need one" is the catchcry of a new advertising campaign targeting sperm donors.

Some clinics have blamed the decline in donor numbers on recent law changes.

IVF clinics were once heavily reliant on university students wanting some quick cash for sperm donations.

But Professor Michael Chapman, a senior fertility specialist with IVF Australia, said that is not the case any more.

"We've got a serious problem in a shortage of donor sperm," he said.

"We've got many couples, many women who are desperate to have a baby, and they don't have a male partner with sperm quality or any sperm to become pregnant so it's a situation where sperm donation is the only way for them."

The Sydney-based group has almost 70 clients waiting for sperm donations but it has only 10 donors on its books.

Professor Chapman, who is also the spokesman for the Fertility Society of Australia, an umbrella group for clinics, says the sperm shortage is Australia wide.

"We have a waiting list of 12 to 18 months to obtain a sperm donor for an individual patient approaching us, so if you came to me tomorrow I couldn't offer you sperm till 2011," he said.

"So if you are 38 that's significant, because your fertility in the next 12 months is probably going to drop 12 to 15 per cent.

"So your chances of getting pregnant when we actually do get the sperm is actually less than it is now."

Law changes

The Fertility Society of Australia blames the drop in donations on recent changes to legislation.

On January 1, Victorian donors were required to have police and child protection order checks, while on the same day in New South Wales law changes required all donors to be placed on a state-held register.

"In the past men could donate sperm knowing that they would never be known to the child, and over the past five to 10 years there has been a change in attitude to that which has given the right of children, or the belief that there is a right of children, to know their genetic background so that has led to changes in legislation," he said.

Sandra Dill, the head of ACCESS Australia, a not-for-profit organisation supporting singles and couples seeking or undergoing fertility treatment, says much of the legislative changes have been for the better.

She says a lack of regulation in places such as the US has had worrying results.

"One donor had 166 children over a number of families which was just hard to believe," she said.

Ms Dill welcomes any bid to boost donors here.

"There's been a critical shortage of sperm donors across Australia for some time and to the extent that where I understand some clinics don't even offer this service unless people bring a known donor," she said.

Professor Chapman said two of Australia's largest IVF clinics, Melbourne IVF and IVF Australia, are now appealing to men's generosity to fill the shortfall.

And while he conceded there are risks that advertising may attract the wrong type of donor, he said there are safeguards in place.

"If men do respond to our advertisement they will be taken through in great detail the implications," he said.

"They will see our counsellor. They will see a genetic counsellor. They will have blood tests to prove they don't have any specific problems they may hand onto a child in the future.

"I expect of probably 100 that come to us, we may only get 10 or 15 who actually decide to go ahead.

"That's 10 or 15. That will be almost doubling what we've got at the moment."