An Auckland University researcher says doctors and clinics need to reduce the waiting time for abortions, which are taking an average of 25 days to arrange.
Martha Silva led a study which looked at the experiences of 2950 women at nine clinics.
She says more than half aborted their pregnancies on or after the 10th week of pregnancy.
Of those questioned, 38% felt they had waited too long and wanted the procedure sooner while 15% thought the wait was too long but did not mind waiting.
Dr Silva says the risks of medical complications increase the longer the foetus is allowed to develop.
Abortion Law Reform Association president Dame Margaret Sparrow says only a third of abortions in New Zealand are carried out before the ninth week of pregnancy - the limit recommended by the Abortion Supervisory Committee.
However, Dame Margaret says she thinks most abortion clinics are doing the best they can within the constraints of the law, and that changes need to be at a legislative level.