Almost two-thirds of U.S. women of reproductive age use some kind of contraception, according to the latest federal data. And millions of them use methods that contain hormones, including birth control pills, intrauterine devices (IUDs), rings, implants, injections, and patches.
Although the specifics vary from method to method, hormonal birth control generally works by halting ovulation and/or changing conditions in the uterus or cervix to prevent pregnancy. And it works well: efficacy rates approach 100% when these methods are used correctly.
But hormonal birth control has a bad reputation. Many women are worried about how hormones like estrogen and progestin may affect their short- and long-term health, to the point that some are quitting birth control and choosing “natural” methods (which are often less effective) instead. A 2022 KFF survey found that about a third of reproductive-age women not currently using contraception avoid it because of concerns about side effects.
“They’re wonderful products, yet we maintain a cultural belief that somehow hormones are bad,” says Dr. Jeffrey Jensen, director of the Women’s Health Research Unit at Oregon Health and Science University. “That’s, in my opinion, simply not true.” (Jensen has received consulting fees from pharmaceutical companies that make contraceptive products.)
Here’s what the research says about hormonal birth control and health.
The side effects of birth control
In the KFF survey, about a third of women using contraception said they currently experienced side effects such as weight gain, headaches, bloating, nausea, mood changes, and menstrual changes. While these issues are usually not severe enough to be medically concerning, they can have a significant impact on quality of life. Studies show that many women who stop using birth control do so because of side effects.
But, Jensen notes, birth control sometimes comes with positive changes as well. It can lessen issues like acne, heavy or irregular periods, and menstrual cramps.
Is birth control linked to cancer?
There is research to suggest that women who use hormonal birth control are at slightly increased risk of breast cancer and cervical cancer. That elevated risk seems to be temporary, though, dropping off after a woman stops using birth control.
And studies also suggest that hormonal contraception reduces the risk of developing other types of cancer, including ovarian, endometrial, and colorectal disease—and those protective benefits seem to last for decades, even well after someone has stopped using birth control.
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When it comes to cancer, the pros and cons effectively cancel out, says Lisa Iversen, an advanced research fellow at the University of Aberdeen in Scotland. In 2017, she co-authored a study on birth control pill users’ lifetime risks of developing cancer, which involved analyzing decades of health data from more than 46,000 women. “Overall,” she says, “we found a neutral balance when you compare the risks and benefits.”
Still, Iversen says it’s always smart to speak with a physician about your specific personal and family risk factors before starting a new prescription.
Does birth control cause cardiovascular issues?
Birth control pills that contain estrogen have been linked to an increased risk of blood clots and stroke. But some researchers have questioned the strength of the association between contraception and cardiovascular problems. The authors of a 2022 review of previously published research concluded that there is little high-quality evidence to prove that birth control causes serious health issues, including cardiovascular complications and cancer. In fact, some recent research suggests birth control pills may actually decrease a woman’s risk of developing heart disease or dying prematurely.
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People with specific risk factors for stroke or blood clots should speak to their physicians before choosing a contraceptive method. But overall, it’s important to keep potential drawbacks in perspective, says Dr. Elizabeth Kinsey, a complex family planning fellow at the University of California, San Francisco’s Bixby Center for Global Reproductive Health. Pregnancy and birth also carry significant health risks, particularly given the U.S.’s abysmal record on maternal mortality, she notes.
Further, Kinsey says, conditions like cancer and stroke are diagnosed relatively infrequently among women of childbearing age. So even if contraception slightly increases a woman’s risk of developing them, her overall risk still remains low.
What about IUDs and other forms of hormonal birth control?
IUDs have a complex past. The Dalkon Shield, a type of IUD that became popular in the U.S. in the 1970s, was eventually linked to health issues including infections and pelvic inflammatory disease, causing some lingering concerns about these devices. Modern IUDs, however, are designed differently and have a good safety profile.
Hormonal IUDs available in the U.S. also do not contain estrogen, only progestin, which should minimize concern about clots and stroke, Jensen says. Studies on IUDs and cancer suggest a mix of pros and cons, similar to those associated with birth control pills: a slightly elevated risk of breast cancer, balanced by reductions in the risk of endometrial and cervical cancer.
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One recent study also analyzed the hormone used in the birth control shot, medroxyprogesterone acetate. It found that prolonged medroxyprogesterone acetate use may be associated with an increased risk of developing a type of slow-growing (and usually benign) tumor in the membranes around the brain and spinal cord. Hormones used in IUDs were not associated with that risk, the study found.
Kinsey says she’d like to see more research on lesser-used forms of contraception, like rings and patches. But based on the science currently available, Jensen says most people don’t have huge reason to worry about using hormonal birth control, although individual risks are worth discussing with a doctor.
“For the most part,” he says, “we should be looking [at the science] and celebrating.”
