New Zealand's abortion rate remains stable and is declining over time, but fewer younger people are having pregnancies terminated.

Figures from Statistics NZ show women in their 20s accounted for more than half of all abortions in 2018.

Just 10 percent of abortions were for women under 20, down from a peak of 23 percent 11 years ago.

About eight in every 1,000 15 to 19-year-olds had an abortion in 2018, compared to 26.7 in every 1,000 in 2007.

Women over 30 accounted for 38-percent of all terminations, up from 28-percent in 2007.

Otago University social psychologist Professor Joe Boden says they may be more engaged in their jobs than they would've been 20 years ago.

"We found that the most frequently given reasons for interruptions to education or careers is when they have their first child. I would expect those remain the same reasons."