"Most of the single women are really aware they are getting older and they don't want to miss that window. Our gay and single women are waiting up to a year and even longer out of Auckland - and that's really tough if you're getting older."
While waiting times had been lessened, general demand had all the while increased.
"We are now really short of donors that we came up with this groovy, quirky campaign that's a little bit controversial, in the hope we'd get a little interest around it.
"We're talking about educated, successful women who know they can care for a child and wish to become mothers."
A woman who featured in last week's Weekend Herald - Hong Kong-born Auckland Council ethnic panel board member Bevan Chuang - wanted to give birth in the auspicious Year of the Dragon.
The shift in recipients also reflected advancements in treating severe male infertility - which wasn't always the reason heterosexual couples needed sperm.
Some saw the donor process as a way of bypassing genetic diseases or conditions, Dr Birdsall said.
Recipients were offered at least four to five non-identifying donor profiles to choose from - and often had the choice of using the same donor more than once.
Profiles covered such physical attributes as height and eye colour, as well as areas of interest, education, social history and health.
Donors could place some restrictions on who they would like their donation to go to, but could not give sperm without accepting their child would be able to eventually learn their identity when they became legally old enough to apply for donation records.
Donors were often inspired after having seen friends and family members struggle with infertility.
"We like our donors to be healthy, less than 45 years old and we screen for a number of infectious diseases," Dr Birdsall said.
"But really, we just want keen guys who want to do a good thing. While many of our donors once were university students, I think now we'd like them to be possibly a little bit maturer, worldlier and to be able to think through the implications of what donating might mean."