As misinformation about women's health spreads like wildfire, the latest research examining hormonal forms of birth control and the risk of breast cancer highlight a crucial challenge: How to communicate scientific nuance in a fast-paced, social-media-driven world.

This was the issue for a comprehensive Swedish study whose findings were frequently misinterpreted online.

For over a decade, researchers tracked more than two million teenage girls and women under the age of fifty. The goal was to examine whether different types of hormonal contraceptives, including birth control pills, implants and injections, were associated with changes in breast cancer diagnoses.

Despite the depth of the research, physicians emphasize that the results shouldn't alarm women or prompt them to stop their birth control. Yet online, the story took a different turn.

Overall, the findings reaffirmed a reassuring message that hormonal contraception remains safe. But the study was nuanced. It also documented small differences in risk based on hormone formulation, along with a modest short-term rise in diagnoses among current or recent users.

The findings align with prior large analysis, including a 2017 Danish registry review and a 2023 meta-analysis. But what set this study apart is its size, duration and detailed tracking of contraceptive types, making it one of the most extensive investigations to date.

Despite the depth of the research, physicians emphasize that the results shouldn't alarm women or prompt them to stop their birth control. Yet online, the story took a different turn. TikTok quickly filled with posts claiming contraceptives cause cancer, going so far as to claim they are as “dangerous as smoking.” Reproductive health advocates warn that this happens when complex findings are taken out of context and reduced to one frightening number.

Here's what the study actually found: women who had used hormonal birth control had about a 24 percent higher breast cancer rate than those who hadn't. But because breast cancer is still uncommon in younger women, that relative increase translates to a small absolute increase — from roughly 54 to 57 cases per 100,000 women per year. If you put it another way, it's around one additional case per 7,800 hormonal contraceptive users annually.

“...[S]ome progestins — particularly desogestrel, a synthetic progestin often used in birth control pills — are linked to a higher risk of breast cancer, while others, such as depot medroxyprogesterone acetate injections, showed no increase.”

Two of the study's epidemiologists, Åsa Johansson and Fatemeh Hadizadeh, both in the Department of Immunology, Genetics and Pathology at Uppsala University, underscored that this rise is short-term; it's highest during current use and fades within five to ten years after stopping the contraception.

Some contraceptives were associated with slightly higher risks. “Not all hormonal contraceptives have the same effect on the risk of breast cancer,” points out senior study author Åsa Johansson, research group leader at Uppsala University and SciLifeLab. “Our results indicate that some progestins — particularly desogestrel, a synthetic progestin often used in birth control pills — are linked to a higher risk of breast cancer, while others, such as depot medroxyprogesterone acetate injections, showed no increase.”

Understanding the findings requires keeping both relative and absolute numbers in view. The problem is that, online, nuance often disappears. Experts say the results should be viewed alongside the well-established benefits of hormonal contraception, including preventing unwanted pregnancies, regulating menstrual cycles, and lowering the risk of ovarian and endometrial cancers. Additionally, the study was not designed to evaluate whether the short-term rise in diagnoses might reflect earlier detection rather than an actual increase in cancer development.

This research does not upend current medical advice. Doctors continue to recommend hormonal birth control as a safe and effective option. But they also stress the importance of women discussing their personal risk factors, which includes family history, age and overall health, with their medical providers.

Where the real danger lies is in the way scientific findings are reshaped online. As this study shows, data without context can be misleading. When careful well-designed research becomes fuel for sensationalized posts, women may make decisions based on fear, not fact. And that, experts warn, is the true public health risk.

The study is published in JAMA Oncology.