PEOPLE who donate sperm or human eggs, who are already in short supply, may be forced to disclose the names of their spouses and children under new legislation tightening rules governing assisted reproduction.

A health policy and family law expert, Jenni Millbank, criticised the NSW legislation, saying if the provision was adopted it would be a "huge incursion" on the privacy of spouses and children of donors.

A professor of law at the University of Technology, Sydney, Professor Millbank said it had the potential to allow donor offspring to track down their biological parents through that person's ex-partner long after they had separated.

"There's a lot of devil in the detail. The regulations are going to have a profound impact on these privacy issues," she said.

While she was not opposed to a register of donor names - which the law stipulates must be kept for 50 years - she felt the net had been cast too wide. "It's absolutely unclear who's going to keep that information and how much information will be included," she said.

She said the requirement, if adopted, would further decrease sperm donations. The numbers fell sharply after January last year when donors had to agree to be identified so offspring could contact them once they turned 18.

A spokesman for the NSW Health Minister, Reba Meagher, said the health department would begin drafting regulations under the new legislation next year.

"This question of whether donors will be required to provide details of their spouse an children is a matter that will be the subject of consultation, the outcomes of which will inform the Government's decision," he said.

It is unclear who will give consent for the donor's spouse and children to be included and whether any subsequent children would also have to be registered.

A clause of the Assisted Reproductive Technology Act, which was passed in the upper house last Wednesday, says a donor "must not obtain a gamete [cell] from a gamete provider, unless the … provider has obtained such information about the gamete provider, the gamete provider's spouse (if any) and any offspring of the gamete provider".

Professor Millbank said she was also "mystified" as to why NSW legislation limited the use of donated gametes and embryos to five families for each donor, half the amount stipulated under the national Reproductive Technology Accreditation Committee's code of practice. "NSW has really just plucked a few things out of the air and gone on a frolic of their own," she said.

"It's kind of crazy. There's nothing to indicate where they came up with this figure and why they decided to depart from the national standard, which is also an international one now the UK has also adopted a 10-family limit and the European Union has recommended it," she said.

"If they wanted to ban the use of donor gamete, they should have said so."