Your Hormonal Birth Control Could Increase Your Breast Cancer Risk

Unsplash/Simone van der Koelen

Countless women use hormonal contraception methods to take charge of their own sexual and reproductive health and to gain a healthy sense of control in in their lives. However, new research suggests that these birth control methods could provide the opposite of relief later in life.

To explore the potential connection between contemporary hormonal contraception use and the development of breast cancer, the team behind this Denmark-based study observed approximately 1.8 million women between the ages of 15 and 49 over a span of 10 years. Some of the women used hormonal birth control options while some of them did not. And at the end of the decade, the researchers assessed how many new cases of breast cancers arose and how many of them existed in women who used birth control.

The researchers found that a higher number of women using hormonal contraception developed breast cancer when compared to those who went without it. For every 100,000 women in the study, hormone-based birth control caused an additional 13 cases of breast cancer each year. The risk level is small, yet significant considering the massive sample size of the study.

Unsplash/Pete Bellis

While most women diagnosed with breast cancer were over the age of 40, the research also suggested that a woman’s heightened risk of developing the disease remains intact for up to five years after her use of hormone-based birth control comes to an end.

It also didn’t matter if the women opted for a pill or an intrauterine device — if progestin was one of the dominant hormones used, their risk of developing breast cancer increased. And progestin is widely used in different birth control products today.

“This is an important study because we had no idea how the modern day pills compared to the old-fashioned pills in terms of breast cancer risk, and we didn’t know anything about I.U.D.’s,” oncologist Marisa Weiss, MD, told The New York Times in response to these findings. “Gynecologists just assumed that a lower dose of hormone meant a lower risk of cancer. But the same elevated risk is there.”

Now, the study is limited in that it was observational. It only took into account other lifestyle factors that could contribute to cancer development risk in a statistical sense, so it can’t conclusively say that the birth control methods alone caused the breast cancer. However, the evidence for causation is strong.

Since approximately 140 million women across the globe use some form of hormonal contraception (for birth control and otherwise), you can bet that we’ll keep our eyes peeled for more data on how these treatments affect our bodies over time.