A study has found an "alarming" number of Australians are playing Russian roulette with their fertility because of a common misunderstanding of the impact that a woman's age has on egg production.

Key points: Research finds that Australians underestimate the impact age has on fertility

Research finds that Australians underestimate the impact age has on fertility Experts says the average age of women having children is approaching 31

Experts says the average age of women having children is approaching 31 Research also finds many are unaware of a simple test which can detect egg reduction

However, one expert has warned a test known as Ovarian Reserve Screening was not the only way to address the issue.

Flinders University researchers released a paper which found both women and men "consistently overestimated natural and IVF-assisted fertility with increasing age".

Professor Kelton Tremellen — who is the medical director for fertility business Repromed — co-authored the paper and said the findings were "alarming".

"There's been a trend over the last four decades of people leaving it later in life to start a family and currently it's approaching about 31 years of age that women are having children," he said.

He said people tend to hold off falling pregnant to fulfil career and education goals but without testing to see if they were prone to premature ageing of the ovaries.

"That's a bit of a concern because fertility declines with increasing age and we know that about 10 per cent of the population will pretty well run out of good quality eggs by their mid-thirties and are at real risk of not being able to have kids at all," he said.

Professor Tremellen said the research also found many Australians were unaware of the test, which can detect whether a woman's egg production has reduced.

He said that condition had very few symptoms.

"They just don't know about it. They don't have any symptoms and they're totally unaware," Professor Tremellen said.

The test is done by taking a blood sample and measures hormone levels.

"Anti-Müllerian hormone is made by the developing eggs and as you get older and you decline in the number of eggs the hormone level drops so it gives us an idea in what the individual's egg count is," he said.

Professor Tremellen, who was the first to introduce AMH as a test of ovarian reserve to Australia in 2004, said women planning on having children in their 30s should take the ovarian reserve screening tests from age 28.

"It costs between $90 and $100," he said.

"It's not a perfect test but it's the best non-invasive test we have.

"If a lady had a result at 28 that was more like a 40-year-old's result then I would be saying 'look, I really think you need to consider bringing forward your plans to have kids because that will give you a better chance of success'."

Freezing your eggs 'not ideal'

Professor Tremellen said women who have low egg reserves can freeze their eggs but it's not "ideal" for a number of reasons.

"I always get concerned about freezing eggs because we don't know what the quality of those eggs are until we thaw them," he said.

"So you don't know what sort of insurance policy you have when you do freeze."

"The pregnancy rate for frozen eggs is probably on five per cent per egg, so you really need to freeze probably 20 eggs to get a decent chance of success.

Professor Tremellen says many men and women underestimated the impact age has on fertility. ( Supplied )

He said it was also an expensive option.

"It's not covered by Medicare so the patient has to pay for that themselves and that's expensive," he said.

Some experts not in favour of testing

Fertility expert Karin Hammarberg of Monash University agreed that there was a misconception around age and fertility.

"It's a big problem," she said. "People overestimate their reproductive life by over 10 years.

"Age is the only and most important factor to determine whether you will or won't be able to have children.

"An older woman with an older man, they will find it increasingly difficult to have children."

However, the former IVF nurse said said calls for to women undergo Ovarian Reserve Screening from age 28 could lead people into a false sense of security when it came to their fertility.

"The test actually tells you about the quantity of the eggs but not the quality," Ms Hammarberg said.

"In terms of natural fertility in a normal woman it's not a good indication.

"When the result is not something you can rely on, I do worry about people who make decisions based on a test that's not reliable.