Otago Fertility Services medical specialist associate professor Wayne Gillett said it was increasingly difficult to find enough men to donate sperm and women to donate eggs.
Ideally the service would need about eight or 10 sperm and egg donors a year, but at the moment there was only about four or five, Prof Gillett said.
About one in five men were suitable donors, he said.
''It is a very simple process for men, but there is a fairly rigorous process done first before we can establish if they are able to be part of the donor process or not.''
Donating eggs was a much more intrusive process and women thinking about donation needed to take that into consideration, he said.
Changes in the way fertility services are run had meant sperm donor numbers had declined during the past 20 years, he said.
''One thing is people are not paid anymore, because that really throws up some ethical questions.
''We used to have students lining up to be donors because they got $25 each time.''
Another reason for a decline was the Human Assisted Reproductive Technology (Hart) Act which meant children born with help of a donor were allowed access to the identity of the donor, once they turned 18.
Although the donor had no legal obligations towards the child, it was a sticking point for some people, he said. There was also a critical shortage of Maori and Pacific Island donors.
Sperm and Egg donation makes up only a small amount of the work at the clinic, but about 30 people still used the donor service each year, Prof Gillett said said.
About half of those who used donors were couples who struggled to conceive themselves while the other half was made up of lesbian couples and single women, he said.
- For more information about donations contact the Otago Fertility Service by calling (03) 474-7752.
