"It's the pressure - if one girl is doing it, they all want to do it. It's the expectation of whatever they think their friends are doing."
However, New Zealand parents have not yet followed the lead of their Australian counterparts, some of whom have paid for their teenage daughters to have cosmetic injections before their big night or as a reward for graduating.
One Sydney clinic, The Medispa at Neutral Bay, estimated that during last year's ball season they injected about 100 high school girls.
"Lips and cheek augmentation are very, very common with the girls prior to the formal and graduation," owner and cosmetic nurse Matty Samaei told the Sydney Morning Herald.
The procedure costs between A$350 and A$750. Cosmetic doctors and clinics spoken to by the Herald said such procedures were not carried out on people of school age in New Zealand.
"I think we have pretty high standards over here," said Dr Catherine Stone, of The Face Place med spa in Auckland City. "With it being quite a small community, the vast majority of cosmetic-medicine practitioners over here are actually excellent.
"That would be seen as outside the realms of best practice."
Dr Garsing Wong, of the Sapphire appearance medicine clinic in Freemans Bay, said some women had work done around the time of their university graduation.