Women are waiting nearly a month on average to get an abortion - and they feel that is too long, research by Auckland University has found.

The study, published in the journal Reproductive Health, looked at the timeliness of services provided by nine New Zealand clinics.

More than half of women at the clinics were having abortions in or after their 10th week of pregnancy, with an average wait of 25 days after seeing their referring doctor.

Lead researcher Martha Silva said abortion was a safe procedure but the risk of complications increased with gestational age.

Clinics and referring doctors needed to make an effort to reduce waiting times, she said.

In an anonymous questionnaire, 38 per cent of women felt they had waited too long and would have wanted the procedure sooner, while 15 per cent thought the wait was too long, but did not mind waiting.

It was the first large-scale study of abortion services in New Zealand and highlighted the need for attention to women's experiences while accessing the services, Dr Silva said.

Part of the delay was caused by the requirement to gain the approval of two certifying consultants before having an abortion.

Labour MP Steve Chadwick has proposed a change to the law to remove the requirement for patients to see two certifying consultants.

The proposal would also encourage abortions to be performed earlier in pregnancy, increase access to medical abortions, remove abortion from the Crimes Act and effectively allow abortion on demand to 24 weeks.