Greater access to long-term contraceptives could explain a steep drop in the teen pregnancy rate, according to Family Planning.
The Salvation Army's State of the Nation report showed the overall pregnancy rate among 15 to 19-year-olds in 2012 had dropped 29 percent on the previous five years, from 59 per thousand to 41.
The number of abortions had fallen by 40 percent in that age group, from 4097 in 2008 to 2489 five years later, while live births decreased 23 percent from 5185 to 3768.
Family Planning executive director Jackie Edmond said a wider range of contraceptives with low failure rates was available.
"Generally, young women are on the pill but with the introduction and the subsidization of implants, we've given them another really significant option," she said.
"Young women in that age group are taking up that form of contraception quite readily."
However, that did not fully explain the drop as contraceptive implants were only subsidized in New Zealand three years ago, Ms Edmond said.