Every year, around 50 Danish women of childbearing age are diagnosed with brain tumours – so-called gliomas.

Although their exact cause is unknown, a Danish study suggests that hormones found in contraceptive pills and hormonal coils can play a role.

More research needed
"We see our results as an important scientific step towards a greater understanding of the causes of brain tumours," David Gaist, a professor of neurology at the University of Southern Denmark and Odense University Hospital, told Ekstra Bladet.

Gaist hopes the study will inspire others to investigate the connection between female hormones and the risk of gliomas. 

"It is important to gain more knowledge because so many women worldwide use hormonal contraception," Gaist commented.

Risk of a glioma is small
Despite the potential risk, the scientist would not advise women to stop using hormonal contraception.

"Gliomas are a rare form of cancer. The risk is very small," Gaist said.  

There is a correlation
The study is based on data from Danish women aged 15 to 49 who were diagnosed with a brain tumour between 2000 and 2009 and did not have cancer before.

The findings show there is a 90 percent higher chance of getting a brain tumour if a woman uses hormonal contraception containing estrogen or a combination of estrogen and progesterone for more than five years.  

Hormonal coils getting popular
The risk is even higher if the contraceptive contains only the hormone progesterone.

While the pill remains more popular – between 25 and 30 percent of women of childbearing age use it – a growing number of women are opting for hormonal coils.

Some 43,000 hormonal coils were prescribed in 2012.