A study published February 12 in the Revista Médica Británica found that current use of almost all the most popular forms of hormonal contraception increased heart attack and stroke risk, even in healthy young women [1]. Researchers reached this striking conclusion after studying 25 years’ worth (1996-2021) of medical records from over two million Swedish women aged 15-49.
Why was the Swedish study so important?
Older studies examining a link between birth control use and cardiovascular risks primarily focused on oral contraceptive (i.e., birth control pill) use, and yielded conflicting evidence on the connection between heart attacks, strokes, and hormonal contraception. Newer research was needed to reflect the risk from all the various types of modern hormonal contraceptives (which now includes arm implants, IUDs, patches, vaginal rings, and injections, in addition to the old standby: pills). Additionally, a very large sample size (including hundreds of thousands or millions of women) was necessary to accurately measure how often very rare events like strokes and heart attacks occur.
What did the researchers learn about heart attack and stroke risk from hormonal contraceptives?
The Swedish researchers found that combined estrogen-progestin oral contraceptive users had twice the risk of both heart attack and stroke compared to women who did not use hormonal birth control. Women who used progestin-only pills had 1.6x higher risk of ischemic stroke and 1.5x higher risk of heart attack compared to non-users. The risk was highest for vaginal ring users, who had more than double (2.8x higher) the risk of stroke and more than triple (3.4x higher) the risk of heart attack. Arm patch users had triple the rate (3.4x) of strokes but no increased heart attack risk, and progestin-only shot Depo-Provera users had double the risk of stroke but risk of heart attack was so low it could not be calculated.
Absolute risk of experiencing a heart attack or stroke remained low overall
Putting a doubling or tripling of rates in context, the actual likelihood of experiencing a heart attack or stroke caused by hormonal contraception still remains low. As an example, the researchers contextualized the risk of heart attack or stroke due to combined estrogen-progestin pills, noting “These values equate to approximately one extra ischaemic stroke for every 4760 women using combined oral contraceptives for one year and one extra myocardial infarction for every 10 000 women per year of use compared with no users.”
The concern comes with the fact that 248 million women worldwide use hormonal contraception. Extrapolating from datos from the Centers for Disease Control and Prevention (CDC), over 9 million reproductive-aged American women were on estrogen-progestin pills between 2015 and 2017. Even one additional ischemic stroke for every 4,760 women taking the pill in a 12 month period would translate to 1,890 contraceptive-caused ischemic strokes that year.
Even one additional ischemic stroke for every 4,760 women taking the pill in a 12 month period would translate to 1,890 contraceptive-caused ischemic strokes that year.
What’s more, many women use hormonal contraceptives for multiple years in a row, even decades (e.g., the Guttmacher Institute estimaciones that the average woman would need to use hormonal contraception for three decades to achieve her family planning goals–unless, of course, she knows about the risk-free alternative: métodos de conocimiento de la fertilidad). While heart attack and stroke risks do not compound the longer you take them, the steady risk remains there year after year.
How do hormonal contraceptives raise ischemic stroke and heart attack risk?
Arterial blood clots or thromboses are the cause of ischemic strokes and heart attacks. Ischemic stroke refers to a clot or other blockage in an artery in the brain, which then prevents blood flow to certain areas. Heart attacks are typically preceded by coronary artery disease. A heart attack (known medically as a myocardial infarction) results when plaque within a coronary artery breaks off and causes a blockage of blood flow (and therefore oxygen) to the rest of the heart.
How does that relate to hormonal contraceptives specifically? Dr Oliver Segal, a British cardiologist and electrophysiologist told Women’s Health UK, “Oestrogen increases the production of clotting factors while reducing natural anticoagulants (which stop blood clotting), shifting the balance towards a greater risk of thrombosis [clotting].”
High blood pressure also aumenta heart attack and stroke risk, and Dr. Segal further explained, “Contraceptives also can raise blood pressure by promoting fluid retention and affecting vascular tone.”
But does the BMJ study really reflect heart attack and stroke risk for the average woman?
The Swedish study researchers purposely excluded women with “arterial or venous thrombosis (blood clots), cancer (except non-melanoma skin cancer), thrombophilia, liver disease, kidney disease, use of antipsychotics, infertility treatment, hormone therapy use (such as hormone replacement therapy), oophorectomy (removal of the ovaries), hysterectomy (removal of the uterus), polycystic ovary syndrome (PCOS), and endometriosis.” They did this to ensure that they were measuring risk associated with the contraceptives themselves, not with other conditions that might on their own raise risk.
But given that this study necessitated the exclusion of large swathes of the female reproductive-aged population, might the researchers have underestimated the heart attack and stroke risks for the average woman on birth control? After all, PCOS and endometriosis are the two most common female reproductive conditions; PCOS afecta a 1 in 10 reproductive-aged women, as does endometriosis [2]. Both are considered underdiagnosed, meaning that true rates are likely much higher. Unfortunately, the widespread prescription of hormonal birth control for reproductive symptoms like painful periods without an official diagnosis as to their cause can only perpetuate underestimates of PCOS and endometriosis prevalence.
The BMJ study was the latest to confirm that progestin-only contraceptives aren’t risk-free
In 2023, Opill, a progestin-only contraceptive, was made available for over-the-counter (i.e., non-prescription) use in the United States. Since Opill doesn’t require a prescription, many people assume that it’s safer than estrogen-containing birth control pills, which are known to raise blood clot risk in particular. However, Opill and estrogen-plus-progestin birth control were found to raise a woman’s breast cancer risk equally en un 2023 British study [3].
The BMJ study is just the latest in a pile of growing evidence that progestin-only contraception isn’t necessarily safer just because it lacks estrogen. While heart attack and stroke risks for progestin-only pill users weren’t como high as the same risks from combined estrogen-progestin oral contraceptives, they were still markedly higher compared to women who didn’t use hormonal birth control.
While heart attack and stroke risks for progestin-only pill users weren’t como high as the same risks from combined estrogen-progestin oral contraceptives, they were still markedly higher compared to women who didn’t use hormonal birth control.
Is hormonal birth control really safe for most young women?
Despite evidence linking hormonal birth control use to heart attack, stroke, blood clots, and many other risks, the Asociación Americana del Corazón maintains that “For most healthy young women, hormonal birth control is safe.” But many young women are no in excellent health.
A 2020 study published in JAMA found that, 19.5% of people aged 20 to 39 (men and women were equally affected) had metabolic syndrome, which is characterized by 3 out of the following: high blood glucose (sugar, low levels of HDL, or “good” cholesterol in the blood, high levels of triglycerides in the blood, large waist circumference or “apple-shaped” body, and high blood pressure) [4]. Metabolic syndrome predisposes individuals to heart disease, stroke, and diabetes.
What’s more, 1 in 10 reproductive-aged American women experience polycystic ovary syndrome (PCOS), and an equal number have endometriosis. Due to underdiagnosis and misdiagnosis, the true number of women with SOP and endo is likely much higher. Both these conditions subir women’s cardiovascular risk. Additionally, 1 in 8 women will experience a thyroid condition in their lifetime, and thyroid problems raise cardiovascular risk as well [5].
The reality: Many young women are not in good health
Additionally, as of 2017-2018, fully 40% of women aged 20-39 were considered obese, according to the Centros para el Control y la Prevención de Enfermedades (CDC). Obesity is a direct risk factor for cardiovascular disease.
En un Healthline artículo about the BMJ study, interventional cardiologist Dr. Bradley Serwer, MD, acknowledged multiple health conditions that predispose hormonal birth control users to issues to cardiovascular risks. He noted, “These groups include those that smoke, have pre-existing blood clotting disorders, those with a history of migraines, those with known cardiovascular and peripheral vascular disease, those with obesity, and those with diabetes.”
Based on these sobering statistics, and the fact that many of the above conditions overlap (occur at the same time in the same person), one wonders how many young women AHA’s statement (“For most healthy young women, hormonal birth control is safe”) actually refers to.
Some birth control options do not appear to raise cardiovascular risk. Should women use those instead?
The Levonorgestrel-IUD
The BMJ study authors noted that the progestin-only Levonorgestrel-IUD was the sólo form of studied hormonal contraception that did not increase heart attack or stroke risk. Still, that doesn’t make the LNG-IUD risk-free.
In addition to potentially severe dolor de inserción, LNG-IUD complications also include the possibility of uterine perforation, breakage, infection, and accidental expulsion (falling out). And since LNG-IUDs function differently from oral contraceptives, breakthrough ovulation and termination of a very early pregnancy are possible.
The copper IUD
As women increasingly abandon hormonal birth control, many are turning to the hormone-free DIU de cobre in their search for more natural, safer birth control. But as we’ve pointed out time y time again, hormone-free does not mean risk-free. The copper IUD is implicated in thousands of breakage-related lawsuits, which have been consolidated into multidistrict litigation and should go to trial this year. Mental health concerns can also be a significant concern with the DIU de cobre, perhaps especially if women have multiple devices inserted within a short time span, as occurred in the tragic case of Army midwife Krista Labbe.
¿Cuál es la alternativa?
Women deserve family planning options and solutions for reproductive issues that don’t jeopardize their health, particularly with such serious risks as heart attacks, strokes, and blood clots. Fortunately, alternatives do exist, and mujeres jóvenes in particular are increasingly turning to them. Interested in potentially coming off the pill and giving fertility awareness a try? These women’s real-life testimonies offer a glimpse into what to expect.
Referencias:
[1] Yonis H, et al. (2025, February 14). BMJ. Stroke and myocardial infarction with contemporary hormonal contraception: real-world, nationwide, prospective cohort study. https://pubmed.ncbi.nlm.nih.gov/39938934/ [2] Deswal R, Narwal V, Dang A, Pundir CS. The Prevalence of Polycystic Ovary Syndrome: A Brief Systematic Review. J Hum Reprod Sci. 2020 Oct-Dec;13(4):261-271. doi: 10.4103/jhrs.JHRS_95_18. Epub 2020 Dec 28. PMID: 33627974; PMCID: PMC7879843. [3] Fitzpatrick D, Pirie K, Reeves G, Green J, Beral V. Combined and progestagen-only hormonal contraceptives and breast cancer risk: A UK nested case-control study and meta-analysis. PLoS Med. 2023 Mar 21;20(3):e1004188. doi: 10.1371/journal.pmed.1004188. PMID: 36943819; PMCID: PMC10030023. [4] Hirode G, Wong RJ. Trends in the Prevalence of Metabolic Syndrome in the United States, 2011-2016. JAMA. 2020 Jun 23;323(24):2526-2528. doi: 10.1001/jama.2020.4501. PMID: 32573660; PMCID: PMC7312413. [5] Soetedjo NNM, Agustini D, Permana H. The impact of thyroid disorder on cardiovascular disease: Unraveling the connection and implications for patient care. IJC Heart & Vasculature. Vol 55 (2024): https://doi.org/10.1016/j.ijcha.2024.101536