Can You Get Pregnant on Birth Control?

If you’re having sex but are concerned about getting pregnant, there’s a pill for that. There are also IUDs, shots, creams, condoms and more.

But are they 100% reliable?

Close, but not quite.

Ob/Gyn Salena Zanotti, MD, explains how you can get pregnant even if you’re on birth control, and steps you can take to lower the chances further.

How birth control works

Different kinds of birth control work differently to prevent pregnancy.

Some use hormones to stop ovulation. That means they keep an egg from being released. Others make it so that a fertilized egg can’t implant in your uterus. And some methods block sperm from getting to an egg.

Let’s look at how different kinds of contraception lower your odds of getting pregnant.

Long-acting reversible contraception (LARCs)

• Hormonal intrauterine devices (IUDs) keep a fertilized egg from attaching to the wall of your uterus. They go by brand names like Mirena®, Liletta®, Kyleena® and Skyla®.
• Copper IUD (ParaGard®) is a hormone-free IUD that uses copper to deter sperm from reaching an egg and interfere with implantation.
• The birth control implant (Nexplanon®) is a small rod inserted into your upper arm. It uses the hormone progesterone to stop ovulation.
• Birth control shots (Depo-Provera®) contain progesterone to keep you from ovulating.

Daily and weekly medications

• Birth control patches (Xulane® and Twirla®) are sticky squares you wear like a bandage. It uses estrogen and progesterone to stop ovulation.
• Birth control pills are medications that contain progesterone or a combination of estrogen and progesterone to prevent ovulation. Birth control pills go by multiple brand names and formulations.

Barrier methods

Barrier methods prevent pregnancy by blocking sperm from entering your uterus. They include male condoms, female condoms, contraceptive gels, spermicides, diaphragms, sponges and cervical caps.

Surgeries (permanent sterilization)

• Tubal sterilization (“getting your tubes tied”) keeps eggs from traveling to your uterus to get fertilized.
• A vasectomy blocks sperm from getting into semen.

Effectiveness of birth control

How effective birth control is depends on the type you use and how you use it.

Surgeries, LARCs and medications are more than 99% reliable if they’re used correctly. Barrier methods are between 85% and 95% effective at preventing pregnancy when they’re used exactly as indicated.

Most birth control failures happen because of human error — not the method itself.

“Missing a pill, going too long between shots or not replacing an IUD on time all reduce effectiveness,” Dr. Zanotti says.

Reasons you could get pregnant on birth control

Some of the most common reasons pregnancy can happen even when you use birth control include:

• Timing: IUDs and implants need to be replaced on time to remain effective. An IUD that’s past its expiration date increases the risk of pregnancy. If you use the birth control shot, you need to keep up with regular appointments. Birth control pills need to be refilled frequently and taken at the same time each day.
• Trouble with barrier methods: Condoms and other devices can break, get damaged or move out of place, which can raise the possibility of pregnancy.
• Medication interactions: “In the past, antibiotics would often lower the effectiveness of birth control pills,” Dr. Zanotti says. Most medications these days won’t affect your birth control, but it’s still important to check the packaging or talk with a healthcare provider about the risk.
• Surgery failure: Tubal sterilization and vasectomy surgeries are highly reliable. But in very rare circumstances, they can fail. If you’ve had a vasectomy, you can still be fertile for several weeks or months.

Tips to minimize risk of pregnancy on birth control

The only way to be absolutely sure you won’t get pregnant is to not have sexual intercourse. Short of that, Dr. Zanotti shares this advice:

• Consider long-acting contraception, like IUDs and implants — especially if sticking to a schedule or properly using barrier methods is tough for you. “The more you have to think about and plan for contraception, the more opportunities there are to make a mistake and lower its effectiveness,” she points out. “That’s why surgery or long-acting contraception, like IUDs, are typically the most effective.”
• Consider procedures like tubal sterilization or vasectomy if you know for sure that you don’t want future pregnancies.
• Replace IUDs and implants on schedule. Hormonal IUDs need to be removed and replaced every three to eight years. The copper IUD lasts 10 years. Implanted birth control is good for three years.
• Keep up with your appointments for birth control shots, typically every 12 weeks.
• Set an alarm or calendar reminder to take your birth control pills or change patches on time. Carry your medication with you if you’re away from home.
• Take birth control pills at the same time each day. Progesterone-only pills are the most sensitive to timing. Taking them just two or three hours later than usual can raise your chances of getting pregnant.
• Use backup methods of birth control, like condoms, if you fall off schedule for your primary birth control method.
• Use care with barrier methods. Pay attention to things like condom expiration dates and confirm that any barrier devices fit well and are in good condition.
• Take caution after a vasectomy by using additional birth control methods until cleared by a healthcare professional. Semen can still contain sperm for weeks or months after the procedure.

Birth control can help prevent pregnancy, but it’s not foolproof. Always use birth control as directed and talk with a healthcare provider about the best methods for you.