If you have been on birth control pills for years, it’s natural to wonder what long-term hormone use is doing to your body. Sure, you’re enjoying the benefits of controlling your fertility and regulating your period, but does that come at a price?

Women tend to expect a trade-off when it comes to having any kind of control over their bodies. (You can enjoy sex without contraception — but you might get pregnant! You can control your fertility — but it comes with a shelf life!) So, it’s normal to wonder what being on birth control pills for 10, 15 years does to you — and worry that the cons might outweigh the pros. We break it down for you here.

How many years can you be on birth control pills?

If you’re healthy, and checking in annually with your gynecologist, you can take birth control pills long term, for as many years as you need them.

Do birth control pills cause cancer?

The short answer: No. There is no evidence that proves birth control pills cause any type of cancer. That said, several studies have found women who take or have taken birth control pills are slightly more or less likely to develop certain cancers — but the studies can’t account for other factors that could influence the development of cancer, so again, the short answer is no.

That’s why women taking birth control pills for years need to regularly consult a physician who knows they’re on birth control pills, knows whether they have any additional health risks, and can monitor their general health in light of long-term hormonal contraceptive use.

Now for the long answer.

Birth control pills and cervical cancer

Several studies have linked long-term birth control pill use to increased risk of cervical cancer. Again — birth control pills do not cause cervical cancer; nearly all cervical cancer cases are caused by the humanpappiloma virus (HPV), a common sexually transmitted infection many people get and never know they’ve had. But there is some evidence that the hormones in birth control pills may be a factor in whether HPV-affected cervical tissue becomes cancerous. (If you’ve gotten an HPV vaccine, you have no reason to worry about cervical cancer and its link to birth control.)

Birth control pills and breast cancer

Several studies have found that women who currently take or have taken oral contraception are at a slightly elevated risk of breast cancer — around 20% more risk than women who have never taken birth control pills. (Certain types of pills had higher or lower risks associated.) One 2017 study suggests breast cancer risk does increase the longer birth control pills are used, but there is little corroborating research.

And finally, for women with a family history and/or a genetic mutation (known as BCRA I or II) that puts them at greater risk for breast cancer, birth control pills may or may not elevate their risk further. A study has associated birth control use for more than five years with a slightly elevated risk of breast cancer among BRCA I carriers, but not among BRCA II carriers. But scientists say the picture is far from clear, and there’s not enough research to categorically say that long-term birth control pill use does or does not contribute to breast cancer.

Birth control pills and ovarian cancer

Confusingly, oral contraceptives appear to offer protection against other types of cancer, such as ovarian. The chances of a woman who has ever taken birth control pills getting ovarian cancer is 30 to 50% lower than the chances of women who have never taken the pill. And long-term birth control pill use is associated with diminishing (and long-lasting) odds of ovarian cancer. This is true, too, for women who carry the BRCA I or II mutation, which predisposes them for ovarian as well as breast cancer.

Birth control pills and endometrial cancer

Women who use or have used birth control pills are also have at least 30% less chance of developing endometrial cancer than women who have never taken oral contraceptives. And again, the long-term side effects of birth control pills are positive: the longer women used birth control, the lower their risk of endometrial cancer.

Birth control pills and colorectal cancer

Women who use or have used birth control pills are also thought to be at slightly less risk of colorectal cancer.

Can birth control pills cause infertility?

Many women start wondering about the effects of long-term birth control use when they stop taking oral contraceptives because they want to get pregnant. Stopping the pill after 10 years or more can be a surprise, and many women report irregular periods, or no immediate periods, giving rise to rumors that birth control pills can cause infertility. But birth control pills do not cause infertility, nor do they cause any long-term effect on fertility that continues after stopping the pill. So, what’s happening?

Even before you’ve stopped using the pill, it’s possible to wonder if there are some fertility side effects from long-term use of birth control pills, as many women report missing periods after prolonged (and proper) use of the pill. It’s not a sign of infertility, however.

“What happens is, over time, the uterine lining can become very thin if you take the pill regularly. All that means is if you stop bleeding on the pill, the lining has become so thin that you don’t have anything to bleed from,” says Dr. Vanessa Cullins, of Planned Parenthood. Stopping the pill allows the ovaries to make more estrogen, which prompts the uterine lining (endometrium) to thicken and periods to resume. (This thinning of the endometrium, by the way, is how birth control pills reduce women’s risk of endometrial cancer.)

After stopping birth control pills, your period may also be irregular; it may take as long as three months for your natural cycle to resume. Health, weight, stress, PCOS and other factors may influence how quickly your cycle reasserts itself. But this readjustment period is possible no matter how long you’ve been taking the pill, and has no bearing on your overall fertility (though it may keep you from being able to become pregnant during that period).

Experts say any changes in menstruation after getting off the pill after 10 or 15 years are probably related to natural cycle changes associated with aging – changes which have been masked by years of regulating menstruation via birth control pills. Alternatively, if your menstrual cycle was irregular before you went on birth control, any irregularity after stopping the pill after years of use could simply be a return to your norm.

Should I take a break from my birth control pills just to be safe?

Sure, why not? Experts say there’s no need, but if it makes you feel better to experience one or two natural cycles, after being on birth control pills for years, then go for it. But just remember, if you aren’t taking birth control pills, you’ll need to use another form of contraception if you want to avoid pregnancy.

Taking birth control pills in your 30s

One thing to know about taking birth control in your 30s, is that most experts advise women to revisit their birth control pills at age 35. Post that age, oral contraceptives that contain estrogen might not be a good idea, because they slightly increase the risk of blood clots and heart attacks — a risk that increases anyway with age, too. (Birth control pills come in two different types: synthetic estrogen-progestin combination pills, or pills that contain synthetic progestin only.)

While the amount of estrogen in combination pills has decreased dramatically in recent versions of the pill, it’s still good to check in with your gynac at this age to see what they advise — this is especially true for anyone who smokes, is obese, has high blood pressure, has diabetes, or has a family history of heart or cardiovascular disease.

Read: What You Need to Know About Heart Disease and Heart Attacks in Women

Are there any other long-term side effects of birth control pills?

Interestingly, there may be – but probably not in any way you’d expect. Research into long-term hormonal birth control use is lacking, but the few studies that exist suggest there may be an effect in the place where you least expect it: your brain. (This isn’t so crazy or scary — contrary to popular belief, birth control pills work in general by acting on hormone receptors in the parts of the brain that regulate our reproductive organs, not on the reproductive hormones directly.)

Depending on what is the source from which the synthetic hormone you’re taking is derived, your brain may change in ways that enhance regions that are typically larger in women’s brains — or, counter-intuitively, enlarge brain regions that are naturally larger in men. As of now, this doesn’t mean much beyond the possibility that long-term use of birth control pills might either make you better at recognizing faces, or improve your spatial skills.

Bottom line?

If you’ve not experienced any negative short-term effects from your hormonal birth control, you don’t have any family history of breast or cervical cancers, and you see your gynac regularly, there’s no reason for you not to take your birth control pills for as long as you want. (If you do have a family history of breast or cervical cancers, you may still be able to take birth control pills long-term — but a doctor would need to advise on that choice.)