26/10/2011 11:35 BST | Updated 26/12/2011 10:12 GMT

Study: Taking The Pill For Ten Years Halves Ovarian Cancer Risk

Women who take the contraceptive pill for a decade could be reducing their risk of developing ovarian cancer by 45%, a recent study has discovered.

Researchers at Oxford University believe that the Pill strongly influence the key hormones thought to trigger cancerous tumours.

The study involved 327,000 women and found that those on the Pill, were 15% less likely to get ovarian cancer - and the risks get lower the longer a woman takes the oral contraceptive.

Women on the Pill for one year reduce their ovarian cancer risks by 2.5%, for five years it was 13% and over ten years, the risks were reduced by 45%.

The study, published in the British Journal of Cancer, believes that although the Pill contains high levels of oestrogen, it reduces the amount produced by the woman's ovaries, which is thought to be the cause of ovarian cancer.

Scientists also found that pregnancy reduces the chances of developing ovarian cancer. Women who had given birth slashed their cancer risks by 29%, compared to women who had never been pregnant. For each baby a woman has, the risks are reduced by 8% per child.

"These days it is not uncommon for women to have fewer children or none at all," Sara Hiom from Cancer Research UK, told the Guardian. "Women tend to be unaware that these reproductive factors have a protective effect on their risk of ovarian cancer."

However, due to the higher levels of oestrogen in the woman's body, it does mean that the Pill consequently increases the risk of breast and cervical cancer.

"To put this in context, it is estimated that if 100,000 women use the Pill for 10 years or more, there will be 50 more breast cancers than would have otherwise occurred, but 12 fewer ovarian cancers," Dr. Richard Edmondson from the Northern Institute for Cancer Research, told the BBC.

To add to these findings, a separate study has also discovered a link between taking the Pill and female health.

Scientists from Copenhagen University found that women taking the contraceptive pill containing drospirenone, desogestrel or gestodene could have a higher chance of developing deep vein thrombosis (DVT).