Whether you’re instructed to stop using birth control before surgery — and when — depends on many factors. Your choice of contraception, risk of blood clots, and the type of surgery all play a role.

Combined hormonal contraceptives can increase your risk of blood clots. So can surgery. Your surgeon may advise you to temporarily discontinue use or switch to a different type to help reduce your risk of complications.

If you’re at high risk of a blood clot or are undergoing a high-risk surgery, you’ll likely be advised to stop 4 weeks before the surgery, says Maria Sophocles, MD, OB-GYN, medical director of Women’s Healthcare of Princeton in New Jersey.

Alternatively, if you’re at low risk of clots and are undergoing a low-risk surgery, you may only be asked to stop 1 week in advance — if at all.

It’s worth noting that blood clots are considered rare. The most recent data suggests that each year, 1–5 out of every 10,000 people assigned female at birth (AFAB) who are not pregnant or taking hormones develop a blood clot.

People who use combined hormonal contraceptives have a slightly higher risk. Each year, 3–9 out of every 10,000 AFAB people who use combined hormonal contraceptives develop a blood clot.

Sugammadex (Bridion), which is often used at the end of surgeries that require sedation, can also affect the efficacy of many hormonal birth control methods.

Combined hormonal contraceptives contain synthetic versions of estrogen and progesterone, two naturally occurring hormones.

Estrogen doesn’t cause blood clots, but it does increase the risk slightly — particularly for clots in the leg (deep vein thrombosis) or in the lung (pulmonary embolism).

The following birth control methods contain estrogen:

Birth control pills are the most commonly prescribed method in the United States. And combination pills, also known as combined oral contraceptives (COCs), are the most commonly prescribed form.

“Statistically speaking, oral contraceptives are the most common reason for blood clots,” says Sophocles.

Progesterone-only options don’t increase the risk of blood clots, says Renita White, MD, OB-GYN of Georgia Obstetrics and Gynecology in Atlanta and Alpharetta, Georgia.

But when it comes to sugammadex (Bridion), all hormonal birth control methods are at risk of failure.

Sugammadex (Bridion) has been shown to disrupt the body’s exposure to progesterone. Consistent exposure is what makes hormonal birth control effective.

If you use birth control pills, this disruption is equivalent to one missed dose. The equivalent for all other hormonal methods is unclear:

The medication typically stays in the body for about 7 days, so it impacts the efficacy of hormonal birth control for at least that long, explains Sophocles.

There’s an increased risk of blood clot with most surgeries, says Sophocles.

This is particularly true for surgeries that last longer than 45 minutes, require extended bedrest during recovery, or involve the bones, adds White.

Many factors influence your overall level of risk, including your:

The following surgeries are generally considered very high risk:

Though not as risky, on average, the following surgeries are considered high risk:

As a general rule of thumb, lower-risk surgeries are typically outpatient procedures where you can leave on the same day.

Higher-risk surgeries are typically inpatient procedures, meaning you’re required to stay overnight or longer, that take place in a hospital.

When in doubt, use a back-up birth control method. The following methods do not contain hormones and can be started and stopped at any time:

If you’re being sedated, plan to use a back-up method during penis-in-vagina sex for the next 7 days.

If you aren’t being sedated but are concerned about your blood clot risk, you might consider switching to a progesterone-only method. Talk with your healthcare professional about your options.

Likely nothing, especially if the procedure is short, you don’t have additional risk factors for clots, and you’re healthy overall, says Sophocles.

The only way to know your individual risk is to talk with a doctor or other healthcare professional. The more they know about your overall health and lifestyle, the more accurately they can assess your overall risk.

Being honest about your smoking habits and overall tobacco use is especially important. Other factors include your risk of pregnancy, current birth control method, and interest in switching methods.

“If you want to stay on the pill, your surgeon might ask you to have chemoprophylaxis, which means taking medication to reduce blood clot risk,” she says. This typically includes anticoagulants like heparin.

Hormonal birth control containing estrogen and surgery can increase your risk of blood clots.

Whether that risk is high enough to warrant a change in contraception depends on your overall health, the type of surgery you’re undergoing, and more.

If you use hormonal birth control and are posed for surgery, talk with your clinician to learn more.

Gabrielle Kassel (she/her) is a queer sex educator and wellness journalist who is committed to helping people feel the best they can in their bodies. In addition to Healthline, her work has appeared in publications such as Shape, Cosmopolitan, Well+Good, Health, Self, Women’s Health, Greatist, and more! In her free time, Gabrielle can be found coaching CrossFit, reviewing pleasure products, hiking with her border collie, or recording episodes of the podcast she co-hosts called Bad In Bed. Follow her on Instagram @Gabriellekassel.