Women reduce risk of developing ovarian cancer by giving birth more than once

The first childbirth could significantly reduce women's risk of developing ovarian cancer, and each subsequent child would further reduce the risk, a new study shows. Having one child promotes a 20 percent lower risk compared to those who never gave birth.

The Cancer Research UK has released a report stating that each baby after the first childbirth could reduce the mother's risk of ovarian cancer by an estimated 8 percent. The findings are based on data analysis of 8,000 women with ovarian cancer.

Women with more than one child are also less likely to develop endometrioid and clear cell tumours. Childbirths reduce the risk of developing the conditions by 40 percent.

The researchers believe that the risk of developing ovarian cancer could be linked with infertility. The presence of endometriosis, or the appearance of endometrial tissue on the uterus, affects the fertility of women and could potentially increase the risk of ovarian cancer, according to lead researcher Kezia Gaitskell from the Cancer Epidemiology Unit at the University of Oxford.

Aside from giving birth, women who had tubal ligation or sterilisation also reduced the risk of having ovarian cancer by 20 percent. The procedure provides women permanent infertility.

The researchers said that tubal ligation reduced the risk by theoretically working as a barrier, blocking abnormal cancer-causing cells to pass through the fallopian tubes to the ovaries.

However, the team noted that women are not necessarily advised to have more children to avoid cancer, as the findings only show that some women who gave birth more than once are at lower risk. The research, which is part of the UK Million Women Study, has been presented at the 2015 National Cancer Research Institute conference in the UK.

“Ovarian cancer – like many other cancers – is not one disease, but different diseases that are grouped together because of where they start," said Charles Swanton, chair of the conference. "It’s important to know what affects the risk of different types of ovarian cancer and what factors impact this.”

Swanton suggests that further studies are needed to develop ways to extend the reduction of risk to all women using the findings of the current study. He noted that new methods would be developed regardless of how many children a woman gives birth to.

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