This may be difficult to digest.

Approximately 250 million women around the globe are estimated to utilize various forms of hormonal contraception. Research has previously indicated a potential connection between the use of synthetic hormones for pregnancy prevention and an elevated risk of stroke as well as heart attacks.

A study conducted by scientists in Denmark investigated the risks linked to various hormonal contraceptive methods, including vaginal rings, skin patches, intrauterine devices (IUDs), under-the-skin implants, injections, estrogen-progestin pills, and progestin-only pills.

Hormonal contraceptives typically contain either estrogen and progestin or just progestin, mimicking the natural hormones found in women’s bodies. Estrogen plays a role in regulating the menstrual cycle, while progestin is a synthetic form of progesterone, essential for maintaining pregnancy.

For their research, the team analyzed 25 years of national prescription data for over 2 million Danish women aged 15 to 49.

Women with previous histories of antipsychotic medication use, various cancers, liver or kidney diseases, polycystic ovary syndrome, endometriosis, fertility treatments, hormone therapies, or other similar conditions were not included in the study.

After adjusting for factors like age, educational background, hypertension, and diabetes, the findings revealed that the estrogen-progestin pill doubles the risk of ischemic stroke and heart attack.

In terms of numbers, this means about one additional stroke occurs for every 4,760 women using the pill annually, and one extra heart attack occurs for every 10,000 women each year.

Ischemic strokes, caused by blockages in brain blood vessels, represent the most common form of stroke.

Non-pill hormonal contraceptives, including the vaginal ring and skin patch, also exhibited higher associated risks. The vaginal ring was found to increase ischemic stroke risk by 2.4 times and heart attack risk by 3.8 times, while the skin patch raised the stroke risk by 3.4 times.

Conversely, progestin-only options like the “mini pill” and certain IUDs had more favorable outcomes. Notably, the progestin-only IUD was the only method that did not show an increased risk.

The researchers cautioned that their study was observational, meaning no definitive cause-and-effect conclusions can be drawn. Other undetected factors may have contributed to the observed strokes and heart attacks.

“While the absolute risks for these cardiovascular events were low,” noted the researchers in a recent BMJ publication, “clinicians should factor in these potential risks when evaluating the benefits and drawbacks of prescribing hormonal contraceptive methods.”

In a related editorial, Royal Institute of Technology postdoctoral researcher Therese Johansson emphasized that arterial thrombosis—the formation of blood clots in arteries that can lead to serious outcomes like heart attacks or strokes—tends to be rare among younger women.

However, given the serious nature of the side effects and the widespread use of hormonal contraception, Johansson advocates for increased awareness campaigns focused on the associated risks linked to different contraceptive methods.

“Such efforts should be coupled with training for healthcare providers to ensure consistent and evidence-based counseling,” she urged in the BMJ.