QIMR finds full-term pregnancy reduces endometrial cancer risk

Queensland research has found that pregnancy can reduce the risk of endometrial cancer by 15 per cent for each baby.

Pregnant mum Caroline McAlpine, 32, with Josephine 2, and Thea, 1, at home in Tarragindi. Picture: Liam Kidston.

New Queensland research has found that each full-term pregnancy reduces the risk of endometrial cancer by 15 per cent for each baby.

It’s well known that having a full-term pregnancy reduces a woman’s risk of developing endometrial cancer, but QIMR Berghofer research shows that the risk reduction continues for up to at least eight pregnancies and even those that end in miscarriage reduce the risk.

The research was led by the head of QIMR Berghofer Medical Research Institute’s Gynaecological Cancers group Professor Penelope Webb who said the findings provided new insight into endometrial cancer, which is estimated to be the fifth most common cancer diagnosed among Australian women.

“We have also clearly shown for the first time that pregnancies that end in a miscarriage also reduce risk of endometrial cancer by about 7 per cent. Unlike many other cancers, endometrial cancer rates are increasing so it is vital that we get a better understanding of the factors that affect a woman’s risk,” she said.

“If scientists can understand what drives endometrial cancer there’s hope that we may be able to prevent women from developing it in the future,” Prof Webb said.

The researchers examined pregnancy data from 30 studies conducted around the world, including Australia, held by the Epidemiology of Endometrial Cancer Consortium. This included 16,986 women with endometrial cancer and 39,538 women who have never had the disease.

First author, Associate Professor Susan Jordan who is now at The University of Queensland School of Public Health, said the findings raised questions about the commonly held belief that hormone levels in the last trimester provide the protective effect against women’s cancers.

“Our analysis in this large group of women shows that while a full-term pregnancy is associated with the greatest reduction in risk for endometrial cancer, even pregnancies that end in the first or second trimester appear to provide women with some protection. This suggests that very high progesterone levels in the last trimester of pregnancy is not the sole explanation for the protective effect of pregnancy. If women who experience miscarriage have a seven to nine per cent reduced risk of endometrial cancer then early pregnancy factors may also be playing a protective role against this disease,” Assoc Prof Jordan said.

“This raises the need for more research to identify other factors that underlie this protective effect,” the researcher said.

Pregnant Brisbane mum Caroline McAlpine will have three children under three years old when her baby is born.

“Motherhood has many challenges so it is a really nice benefit that it helps reduce the chance of cancer in the womb,” she said.