The decision to impose radical treatment on a severely disabled girl has come under fire by advocacy groups.
Eight year old Charley Hooper has the mind of a baby, the body of a young girl - and that's the way it will always be.
"A child like this, a childlike Charley is better off small rather than big", her mother Jen Hooper told the Sunday programme.
Severely disabled as a result of an injury at birth, Charley was four years old when her parents Jen and Mark Hooper took her to a doctor in South Korea to begin controversial hormone therapy.
"We didn't do this to Charley, we did it for Charley".
Known as the Ashley Treatment the intense hormone therapy stunts a child's growth and brings on puberty. The next phase is the surgical removal of the uterus and breast buds. A girl would be unable to menstruate, get pregnant and grow breasts.
"Mark and I were like Oh my God, this is amazing. Imagine if we could do this and always be able to carry her like the new-born baby her brain will always be."
Charley began the hormone treatment in Korea and when the family returned to New Zealand she was monitored on the drug for three years by paediatric endocrinologist Professor Paul Hofman.
"The use of high dose oestrogen to make the child smaller has justification certainly in the context of this family they wanted to able to look after the child for longer."
Then last year, aged seven, Charley underwent a hysterectomy at Starship Hospital in Auckland, a procedure deemed reasonable by the Auckland Clinical Ethics Advisory Group. The group refused to comment on the procedure, but the paediatric endocrinologist who guided the family through the procedures admits the decision making wasn't easy.
"Even among my colleagues there was dissension, Some people said it was an appropriate thing to do, others didn't."
Trish Grant from IHC says denying Charley the chance to be a sexually mature, fully grown woman is a breach of her human rights.
"It worries me that the people the medical people making these decisions have no deep or current understanding of disability rights."
But Jen Hooper says keeping her daughter small preserves her right to dignity.
"I'm damned proud of what we've done I'm incredibly proud of what we've managed to achieve for our little girl."
You can see Charley's story on Sunday at 7pm.