Peter Lewis never expected when he donated sperm as a young medical student in the 1980s that his anonymity would be protected.
He and his friends were recruited at a lecture theatre, paid $30 and promised that their identities would never be revealed.
"I never bought this anonymous thing, in any way, in any form," Dr Lewis said.
"I remember very clearly saying to my friends, 'How can this hospital say anonymity will be given to us when laws are not made by administrators? Laws are made by judges and politicians.'"
His words proved prescient in 1998, when his home state of Victoria removed anonymity completely, followed by the rest of the country seven years later.
Fertility clinics predicted the number of men willing to donate their sperm would plummet if anonymity was removed.
But research from Flinders University shows that the reverse has occurred, with a steady increase in donations since 2005, when the National Health and Medical Research Council directed clinics not to use anonymous donations.
All 80 clinics that are required to follow the guidelines as a condition of their accreditation were contacted by the researchers and asked to provide their donor numbers in every year from 2000 to 2012.
Data was obtained from 62 per cent of clinics and Victoria was used as a control group because anonymity had already been removed.
There was a 42 per cent increase in donor numbers in the year that anonymity provisions were removed in all states except Victoria, and a general upward trend over the following years.
The results were deemed a greater reflection of donation figures in Victoria, South Australia, Western Australia and Tasmania than NSW and Queensland, where only around a quarter of clinic data was captured.
The study was published in the Journal of Law and Medicine.
Researcher Damian Adams said the increase might be due to recruitment strategies, or a greater willingness by some men to donate under the more transparent regime.
The findings flew against another study where men said they would be less likely to donate if their anonymity could not be guaranteed.
"Perhaps there are different people now donating," Mr Adams said.
"There is also a study which shows that some donors are more open to the release of information over time. It is an incredibly complex area that can change for the donor during their lifetime."
But andrologist David Handelsman said the study's interpretation was not borne out by the Andrology Department's experience at Concord Hospital.
It closed its 25-year-old sperm donor program in 2005 after the anonymity provisions were removed.
In the 1980s and 90s, a single call for sperm donors would regularly bring dozens of offers when donors could view it as a one-off, no-obligation gesture like blood donation to help complete a family, Professor Handelsman said.
But after anonymity could no longer be guaranteed, similar calls often had nobody responding at all.
"The idea that historically there was no drop in numbers is absolute nonsense," Professor Handelsman said. "The fact that current clinics can find people with a lot more effort, with payment, doesn't mean there was no drop-off at the time when anonymity was eliminated."
The NSW government is introducing a bill to penalise clinics caught destroying donor records, but stopped short of recommending a central database where donor records are kept because of the financial impost to the fertility industry.
Opposition spokesman on health Walt Secord is moving an amendment to set up a central registry to protect the records and allow donor-conceived people to obtain non-identifying information about their biological fathers, including their medical history.
Geraldine Hewitt, who was conceived by an anonymous sperm donor in 1982, tried for years to find her biological father, but abandoned her search after a social worker contacted one man.
He was at work when he took the social worker's call, confirming that he had donated sperm in the relevant years and had received a letter from the hospital seeking to establish whether he was Ms Hewitt's donor.
"He said, 'Unfortunately my wife and I are having difficulty conceiving right now and I haven't wanted to break the news to her at this time'."
She still cries to speak the words.
"I was horrified that she had intruded on his privacy in this way. For me, the door is shut now."
Dr Lewis was eventually contacted by one of his biological children - they are now friends and he has become the godfather to his granddaughter - but he sometimes wonders if his life would have been different had he never donated at all.
One morning when he came in to donate sperm, he was informed by a receptionist that one of his babies had been born with an abnormality and his sperm would no longer be required.
"It was the most appalling piece of genetic counselling," he said.
As he moved through his 20s and his friends settled down with partners, he believed it would be dangerous to have children and remained single.
Only much later did he discover the condition was not hereditary.