Infertility in Kiwi women has the potential to become a prevalent problem, researchers say.
An Otago University study of 1000 Otago-Southland women between 25 and 50 has turned up concerning results.
About a quarter of those who had ever tried to become pregnant or had become pregnant, experienced infertility.
That equated to trying for at least 12 months or needing medical help to conceive.
Among women over 40, 14 percent had not had children, although about half of that group wished they had.
Researcher Antoinette Righarts said unresolved fertility, or remaining childless, was most common in women over 35, which highlighted the risk of delaying a family.
Paper co-author Wayne Gillett said the results confirmed infertility was a bigger problem than previously estimated.
"Such high proportions of women experiencing infertility and seeking help to resolve their fertility issues will continue to put substantial pressure on under-funded infertility services," he said.
It was a particular worry among older women, those from lower socio-economic groups and non-European ethnic groups.
The paper was published in the New Zealand Medical Journal on Friday.