A new study has found a link between a significantly less risk of ovarian cancer and two years of cumulative breastfeeding.

Women who breastfeed for two years of their lives are significantly less likely to develop ovarian cancer, according to groundbreaking public health research.

Almost a decade ago, Curtin University public health professor and medical doctor Colin Binns led a study looking at the relationship between ovarian cancer and prolonged lactation. It appeared that woman who breastfed did have a lower incidence of ovarian cancer, and while the results were promising, the research was not quite there yet.

In recent years Dr Binns undertook the study again, this time with a larger study group and a more narrowed focus.

A handful of Curtin University and Chinese researchers studied about 1000 woman in China's Guangdon Province for a year, and processing the results took "longer than that", Dr Binns said.

They discovered women who had breastfed for at least 20 months of their lives were 60 per cent less likely to develop ovarian cancer.

The period of breast feeding can be spread out across multiple children with the same result, according to the study.

"The longer you breastfeed the more the effect is," Dr Binns said.

"But in order to do our scientific calculations you've got to pick a time so that you can work out how effective it is."

Dr Binns suspects the results were linked to lower periods of ovulation.

"It's to do with a suppression of ovulation by breastfeeding, and that's what we think is the explanation," he said.

Dr Binns was hopeful the research could now be expanded to look at other cancers that might be related to the reproductive system.

"It's really fascinating to see that breastfeeding is a primary benefit to mothers like this," he said.

"There are lots of reasons why mothers should breastfeed for the health of their infants, and here's another reason to add to that for their health as well."

Dr Binns said there were a lot of reasons mothers cut breastfeeding short, but he hoped the results of his study would encourage mothers.

"There are a lot of mothers who are in situation where they have to return to work or where there are other social pressures where it's not possible," he said.

"Breastfeeding must be encouraged and supported where possible."

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