There's concern parents could be caught out by the Government's planned gay conversion therapy law.
Under the Bill, they could face jail time if they stop their children from taking puberty blockers.
But the minister doubts that would actually happen.
Puberty blockers - also known as hormone blockers - are medication that delay unwanted physical changes that don't match someone's gender identity.
Youth health expert Dame Sue Bagshaw is confident they are safe.
"They are totally reversible so that when you stop them your own hormones grow up again," she says.
She's supportive of transgender children using them to delay puberty.
But she's worried the Government's new conversion therapy law goes too far - because of the risk parents could end up in jail for preventing their children taking the blockers.
"I think that would be way too extreme," Dame Sue says. "Criminalising things is not a good thing, it doesn't get us anywhere."
Under the Conversion Practices Prohibition Bill, anyone intentionally changing or suppressing someone's gender identity or sexual orientation could be breaking the law. That includes parents who stop their child from using puberty blockers.
"We only want serious cases to be criminalised and we've designed the legislation in that way," says Justice Minister Kris Faafoi.
But ACT Party leader David Seymour is concerned the Bill goes too far.
"Parents should be able to have frank and open conversations with their kids about delicate matters without the threat of going to jail," he says.
But Faafoi doubts that would actually happen, saying there are many steps to get to that point.
"The Attorney-General of the country has to consent to a case going forward to make sure there's enough evidence of that and that it's in the public interest."
The Ministry of Health maintains puberty blockers are safe and reversible. They can be given to children who display what's called gender dysphoria, where they feel they're in the wrong body.
"It buys you time, what these young people need is time as they work through what their identity is," Dame Sue says.
An identity Dame Sue is urging parents to be supportive of.