Some hormonal birth control products, including the vaginal ring and skin patch, may increase the risk of a blood clot, heart attack or stroke, new research suggests.
A peer-reviewed study published in the British Medical Journal on Wednesday showed that the use of contraceptives containing estrogen and progestin, which are female hormones, was linked with an increased risk of blood clot, stroke and, in some cases, heart attack compared to women not using hormonal birth control.
“We know that estrogen-based contraceptives, for example, can increase a woman’s risk of having blood clots, so that’s where that risk of heart attack and stroke can happen,” said Katie White, director of health systems with the Heart and Stroke Foundation of Canada.
“For women in particular, we know that their risk changes across their life span and that depends a little bit on the protective effects of estrogen, which change of course, through a woman’s life course,” she told Global News in an interview.
Age also has a role to play, with those over the age of 35 at a “higher risk, especially if they have other risk factors,” such as smoking, pre-existing medical conditions, previous stroke or heart condition, high blood pressure or medical complications from pregnancy.
This new study adds to growing evidence linking hormonal contraceptives with the rare but present risks of blood clots and cardiovascular diseases, though the risks remain significantly lower than the risks of blood clots that come with pregnancy and the postpartum period.
Danish researchers found that the associated risk for blood clots was highest for estrogen-containing products, particularly the vaginal ring and skin patch.
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The associated risk of stroke increased two- to three -fold with the use of combined estrogen-progestin vaginal ring and patch.
The combined estrogen-progestin pill was also linked with double the risk of stroke and heart attack, but no cardiovascular risks were associated with the use of a progestin-only intrauterine device (IUD), the study said.
“Although absolute risks were low, clinicians should include the potential risk of arterial thrombosis in their assessment of the benefits and risks when prescribing a hormonal contraceptive method,” the authors concluded.
More than two million women in Denmark aged 15-49 years were included in this observational research that looked at data from 1996 to 2021.
A 2019 systematic review published in the Frontiers in Neurology journal found that higher estrogen dosage in birth control pills “significantly increased” the risks of stroke.
Another 2003 study in Jama Network said estrogen plus progestin “increases the risk of ischemic stroke in generally healthy post-menopausal women.”
HealthLink BC information about the birth control patch notes that it “delivers more estrogen than the low-dose birth control pills do” and that “women who use the patch are slightly more likely to get dangerous blood clots in the legs and lungs than women who use birth control pills.”
The Heart and Stroke Foundation of Canada advises that all women with congenital heart disease should discuss contraception and pregnancy options with a health-care expert who specializes in their risk factors.
White said other risk factors include age, diet and blood pressure management.
The most common signs of stroke can be spotted with the acronym FAST.
This includes face dropping, arm weakness and speech difficulty — all of which indicate that it’s time to call 911 immediately.
Chest pain, light-headedness, feeling out of breath, leg tenderness and leg swelling are the most common symptoms for blood clots, according to Thrombosis Canada.