Hormonal birth control is a convenient and effective way to prevent pregnancy for millions of women around the world. However, its hidden risk could be putting many women’s lives in danger. A new study conducted by the scientists in Denmark has found that certain contraceptive methods like vaginal ring, skin patch, and estrogen-progestin pills, can significantly increase the likelihood of heart attack and ischemic stroke.
According to the University of Colorado, estrogen in birth control pills, patches, implants, rings and injections can cause blood to clot easier, which can lead to heart attack if the clot blocks blood flow to the heart, or can cause a stroke if the clot blocks blood flow to the brain.
Danish scientists in a study published in BMJ attempted to find out how the hormonal contraceptives like vaginal rings, skin patches, intrauterine devices, implants inserted under the skin, injections, estrogen-progestin pills and progestin-only pills increased cardiovascular risk.
Hormonal contraceptives prevent pregnancy primarily by inhibiting ovulation, meaning they stop the ovaries from releasing an egg. They also thicken cervical mucus, making it more difficult for sperm to reach any egg that might be released. Additionally, these contraceptives thin the lining of the uterus (endometrium), which can further reduce the likelihood of pregnancy.
The details of the study
For the study, the national prescription records of over 2 million Danish women aged 15 and 49 were considered.
The women with a history of antipsychotics use, cancer, liver disease, kidney disease, polycystic ovary syndrome, endometriosis, infertility treatment, hormone therapy or other conditions were not included.
After accounting for factors like age, education, high blood pressure, and diabetes, researchers found that the estrogen-progestin pill, commonly known as the birth control pill, was associated with a twofold increase in the risk of ischemic stroke and heart attack.
Using this contraceptive method could mean one extra stroke for every 4,760 women taking the pill for a year and one additional heart attack for every 10,000 women per year of use.
An ischemic stroke happens when a blood clot or plaque blocks blood flow to the brain. This can cause brain damage, disability, or death. It’s a life-threatening emergency. It is the most common type of stroke.
Apart from pills, other estrogen-progestin contraceptives like vaginal ring and skin patch, were also linked with increased risks of heart attack and stroke.
It was found that the vaginal ring raised ischemic stroke risk 2.4 times and heart attack risk 3.8 times, while the patch raised stroke risk 3.4-fold.
Safer contraceptives
Progestin-only products which include the mini pill and implants didn’t raise risk of cardiovascular issues that much. The progestin-only IUD, the researchers found, was found to be the only contraceptive not linked to a higher risk.
However, being an observational study, it could not draw any definitive conclusions and the researchers thought there could be other factors too that may be raising heart attack and stroke risk that they didn’t consider.
“Although absolute risks [of these incidents] were low,” the researchers wrote this week in the BMJ, “clinicians should include the potential risk … in their assessment of the benefits and risks when prescribing hormonal contraceptive methods.”
Hormonal contraceptives can also cause other side effects such as nausea, headaches, mood changes, and weight fluctuations. Some users may experience irregular bleeding, breast tenderness, or reduced libido. In rare cases, they can increase the risk of blood clots, high blood pressure, stroke, or heart attack, especially in those with underlying health conditions.
Progestin-only contraceptives, such as the mini-pill, hormonal IUDs, and implants, are generally considered safer for heart health than combination pills. Non-hormonal options like copper IUDs and barrier methods pose no cardiovascular risk.
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