Parents of young girls with cancer face a tough choice on taking and storing ovarian tissue - because at present it's illegal to have the tissue put back in.
Auckland mum Carolyn Little's daughter Claudia is 6 and was diagnosed with kidney cancer when she was 4.
When a Starship paediatric oncologist told Little and husband Mark that radiation treatment would probably render Claudia infertile, they sought expert advice.
"I would have done anything," said Little.
The Littles paid Dr Mary Birdsall of Fertility Associates to operate while Claudia was in theatre at Starship having her kidney removed. And they pay about $600 a year for the tissue to be stored.
"They took a sliver of her ovary. It's on ice," said Carolyn. "What they're hoping to achieve is that in that sliver there'll be lots of eggs. But here in New Zealand you can't legally defrost that yet, so we don't have the legal right to be able to use that."
The Advisory Committee of Assisted Reproductive Technology (Acart) has not yet approved ovarian tissue being placed back in a patient.
"It's pretty hard not knowing whether or not we'll be able to use it. She's young, so we haven't thought much further down the track.
But we'll fight all the way to get it released," said Carolyn.
Starship spokesman Mark Fenwick said the hospital was waiting for more evidence to help clinicians make informed decisions. "It has to be weighed up on a case-by-case basis."
Dr Birdsall said about 30 women's and two children's ovaries were in Fertility Associates' freezer.
Adult woman having cancer treatment almost certainly face sterility. They could opt to freeze embryos, eggs or part of their ovary. But girls who hadn't hit puberty had only ovarian tissue.
Danish researcher Claus Andersen, who was in Auckland last week, said only 17 children had been born worldwide as a result of transplanted frozen or thawed ovarian tissue.
Acart member Andrew Shelling, who is associate professor in the department of obstetrics and gynaecology at Auckland University, said: "The possibilities are really great for the future ... However, the success rate is very low at the moment. It's still in a very experimental phase."