Many Kiwi women actively keep tabs on their ovulation - yet relatively few are able to accurately pinpoint their fertile window.

That's according to a new study in which just 13 per cent of women surveyed were able to identify their fertility window, despite a third reporting that they monitored their ovulation.

The senior author of the paper, just published in the Australian and New Zealand Journal of Obstetrics and Gynaecology, says health professionals themselves may need help in busting common myths around ovulation and conception.

In the Otago University study, a sample of 1034 women aged 25 to 50 living in southern New Zealand were asked to fill in a fertility questionnaire.

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More women who had ever monitored ovulation correctly identified the fertile window, although the proportion was still low, at just 13 to 18 per cent.

The majority of surveyed women who said they had monitored their ovulation did so because they were trying to get pregnant, but the researchers say that poor fertility knowledge may reduce the likelihood of conception.

The study also found ovulation monitoring was independently associated with seeking medical help to conceive, education and fertility experience - but not with knowledge.

The authors concluded that fertility knowledge needs to be addressed - especially among women intending to conceive.

"When a couple are trying to have a baby, problems like age, endometriosis and male problems are always touted - but no one ever considers knowledge, and that's one of the things we often see," said Professor Wayne Gillett, a researcher at the university's Dunedin School of Medicine and medical director at Fertility Associates Dunedin.

"Contributing to their fertility is just the fact that they are using the wrong time."

Gillett said there was one enduring myth that the best time in the menstrual cycle to conceive was during, or even after, ovulation.

"The reality is that the fertile window is a pre-ovulation phenomenon - it happens before ovulation."

Conception rates, he said, may be improved by "just being aware of it, and getting rid of those testing kits a lot of people use - it's all very fine telling you when you're ovulating, but it doesn't tell you when to have sex".

Gillett also saw a need to ensure clinicians were giving the right information to patients.

"I suppose what we are trying to do here is to educate health providers about this, and make sure that our GPs are getting proper advice."