When you’re shopping around for the best birth control for you, there are lots of things to take into consideration. You’ll want to know how your method of choice affects your monthly cycle, what side effects it might cause, and how long it will keep you covered.
But one of the biggest considerations is how well it prevents pregnancy—whether it’s because you’re done with kids, you're never having any, or now just isn’t the time.
The most effective methods are the ones that don’t require much from users, explains Justine Wu, MD, MPH, assistant professor in the department of family medicine at the University of Michigan and chair of the board of the Association of Reproductive Health Professionals. "Anything working on its own is going to be [more effective] because there's no human error," she explains. "There's no need for user activity, monitoring, or adherence; you don't have to take a pill, get to the doctor's office to get your next shot, or put anything in your vagina."
When it comes to measuring , experts use data based on “typical use,” or how real sexual human beings use each method. The effectiveness rate is calculated by counting the number of women out of 100 who experience an unintended pregnancy during the first year of typical use.
Since effectiveness is so important, it's a good idea to use effectiveness rates as a guide for what birth control to go with. We've laid out the rates (based on Centers for Disease Control numbers) for every method out there—from the most reliable to the iffy. If you’re in the market for a new way to keep your body baby-free, this cheat sheet is for you.
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.05 pregnancies per 100 women in a year
This matchstick-size progestin-releasing implant is placed by a doctor under the skin high up on your inner arm. The progestin thickens cervical mucus, making it tougher for sperm to reach an egg. That is, if one is released. Progestin can also halt eggs from leaving the ovaries to begin with.
Once the implant is in (it takes just minutes), there’s really not much you need to do. Your homework actually should come beforehand: talking to your doc about how this long-acting, reversible contraceptive (LARC) method will affect your body. The implant’s effects are systemic, meaning the hormones travel through your whole body, and that could cause side effects.
Another thing to consider is how comfortable you are with this tiny implant placed just under your skin. "Some women feel uncomfortable with or don't like the idea of having something in the uterus," so they prefer an [arm] implant to an IUD," explains Taraneh Shirazian, MD, assistant professor in obstetrics and gynecology at NYU's Langone Medical Center. Like an IUD, the implant is "one of the options that you don't have to think about, that don't require ongoing maintainence."
Otherwise known as a vascectomy, male sterilization involves cutting or blocking the vas deferens, the tubes sperm travel through from the testicles. If sperm are blocked from leaving a man’s body, you can’t get pregnant—simple, right?
While a vasectomy can be reversed in many cases, the procedure is meant to be permanent. It's also less invasive than female sterilization, which involves abdominal surgery and has a greater potential for complications, says Dr. Shirazian. "Vasectomy is much less risky because it's done in the doctor's office with local anesthesia." As long as you and your partner are sure—really sure—that babies are not in your future, your partner is a candidate for this method. Once it's done, there's nothing more you need to.
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.2 pregnancies per 100 women in a year
This tiny, T-shaped device is placed in the uterus by a doctor during a 15-minute or so office procedure and left there from three to six years. Four types of hormonal IUDs have been approved by the FDA; each works by releasing progestin (just like the implant and some birth control pills). The hormone thickens cervical mucus, making it harder for sperm to reach an egg, and it may also stop ovulation, so no egg is released.
Like an implant, once you have an IUD, there’s little for you to do to make sure it’s smooth sailing. But you need to be sure about the method before having one inserted. To get a sense of whether it's right for you, talk with your ob-gyn about when, if ever, you plan on becoming a mom. Fill her in on how your periods go each month as well, and ask abou the potential side effects (such as breakthrough bleeding and breast tenderness).
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.5 pregnancies per 100 women in a year
Female sterilization (or tubal ligation) means blocking or cutting the fallopian tubes, which prevents an egg from traveling to the uterus and being fertilized by sperm. This is also a permanent form of birth control (though in some cases women have had it reversed and gone on to get pregnant), and it’s a somewhat more complicated surgery than a vasectomy is for a man.
There’s nothing you need to do to make sure this method is effective once you wake up from the operating room. But all surgical procedures come with risks. (Especially since you'll be given general anesthesia.) Unlike the implant or hormonal IUD, sterilization won't affect your cycle.
"If a woman had severe anemia from heavy menstrual cycles, sterilization is going to prevent her from getting pregnant but it not help with her bleeding problem," says Dr. Wu, "whereas with a hormonal IUD, some women will experience decreased bleeding."
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.8 pregnancies per 100 women in a year
Like hormonal IUDs, the copper device is also placed in the uterus and left alone—this time for up to 10 years. The difference is, the copper version doesn’t contain any hormones. It’s the metal itself that prevents pregnancy by making the uterus inhospitable to sperm. The copper IUD can also be inserted in the first few days after unprotected sex as emergency contraception.
Once it's in—it involves the same insertion procedure as the hormonal IUD—you won’t need to worry about maintenance. And contrary to the rumor, the copper IUD, like all IUDs, is a good option for any woman who knows she doesn't want to be pregnant in the next decade, whether she's already had a baby or has not.
"It used to be that women felt they had to have had a baby [before getting an IUD], and that has slowly shifted," says Dr. Shirazian. "IUDs are good methods for women of any age regardless of partners and pregnancies."
Some women prefer the copper IUD because it's totally hormone-free, says Dr. Wu. She's less likely to recommend it to women with heavy or painful periods, she says, since it may make those period side effects worse.
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The birth control shot
6 pregnancies per 100 women in a year
The birth control shot is another method that relies on the hormone progestin to thicken cervical mucus and prevent sperm from ever reaching an egg. Progestin may also stop ovulation, so no eggs reach the uterus at all.
The shot is administered by a healthcare provider every three months, so it’s important that you’ll be able to make those regular appointments in order for this method of birth control to work its magic, Dr. Shirazian says. "Don't delay your shot, because some women can get pregnant in the interim."
She says the shot may be more likely to result in weight gain than other hormonal birth control methods, so she'll often recommend another choice, but the shot "might be a good option if you have trouble remembering to take the pill."
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9 pregnancies per 100 women in a year
The Pill, aka oral contraception, may still be what many women think of first when we think of birth control. But there are more types of birth control pills than ever before: combination pills that contain estrogen and progestin, progestin-only pills, and extended-cycle pills that reduce the frequency of your period. A conversation with your doctor can help you find the one that's right for you.
Most birth-control pills work by stopping ovulation, so no egg is released at all. They also thicken cervical mucus. And while side effects range from breakthrough bleeding to way lighter periods to skin changes, pills that contain estrogen can raise a woman's risk of certain health conditions, such as blood clots (if you also smoke).
The tricky thing about the Pill is that in order for it to work, you have to remember to take it every single day around the same time, give or take an hour or two, says Dr. Shirazian. If the Pill's effectiveness and reversibility (miss just one pill, and you're at risk of conception), enlist the aid of a daily reminder in your phone—or try an app that can help keep you on schedule, like or .
The birth control patch also contains estrogen and progestin and halts ovulation, same as oral contraception. But instead of having to remember to take a pill every day, you just stick on a new patch once a week (you take it out the week of your period), and you're covered. Usually placed on the belly, upper arm, back, or butt, the patch emits hormones that are absorbed through your skin.
The downside of the patch is that you're in charge of placing it correctly (and can't go on your breast, just FYI), remembering to slap on a new one, and checking periodically to make sure it hasn't fallen off accidentally and rendered you baby-ready. "It has to be well-applied—the corners can't be coming up—in order to make sure you're getting the targeted amount of hormones," Dr. Shirazian says.
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9 pregnancies per 100 women in a year
Another hormonal birth control option is the vaginal ring, which you wear inside your vagina for three weeks and take out for a week to have your period. It releases estrogen and progestin to stop ovulation and thicken cervical mucus; both hormones are absorbed through the vaginal lining.
Placing it correctly helps the ring work best, says Dr. Shirazian. "Sometimes people say they feel it or it comes out easily. That usually means it's not really well-applied. Make sure you push it up into the vagina as far as possible." You'll also need to keep track of when it's time to put in a new one and how long you've gone without it.
"You can technically take it out for sex," says Dr. Wu. "It works by releasing hormones in a very slow, steady state, so 20 to 30 minutes of sex is not going to make a difference. That being said, it's not recommended to take it out for more than three hours at any time. You need to remember to put it back in."
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12 pregnancies per 100 women in a year
This rubbery barrier fits inside your vagina and covers your cervix, preventing pregnancy by locking sperm out of your uterus. They come in different sizes (just as women do), so you’ll need to be fitted for one at your doctor’s office. And they should always be used with spermicide, which immobilizes or kills sperm as they try to sneak through the diaphragm on their mission to fertilize an egg.
A diaphragm emits no hormones, and you only use it when you're ready to have sex (you just pop it in, and you're good to go). But it has to stay in for at least six hours after sex, or else any waiting sperm might get inside your body. "It can be tricky to not remove it prematurely," Dr. Shirazian says. Perhaps this is why it's effectiveness rate isn't as high as it should be.
These latex or polyurethane sleeves act as a barrier preventing sperm from coming anywhere near your unfertilized egg. Worn properly, condoms also protect against STDs–unless you’re using a lambskin condom, which isn’t as effective at preventing microbes from spreading.
Condoms are one of the oldest types of contraception, but even after centuries of use, people still place them on incorrectly, says Dr. Shirazian, which is why they aren't as effective as they should be theoretically. "I hear all the time that a condom breaks! A condom should not break if it's been put on correctly," she says. Make sure it's unrolled all the way down the shaft of the penis with a little room at the top—and wait until the penis is erect to do so, she says. "Condoms used well, work well," agrees Dr. Wu.
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21 pregnancies per 100 women in a year
Inserted into the vagina somewhat like a diaphragm (and up to eight hours before sex!), the female condom covers the cervix to prevent sperm from entering. It’s not as effective as a male condom—and it’s not as effective at preventing STDs, either.
A lot of that is because it's a little complicated to insert and position correctly. Unlike a male condom, it doesn't have anything to fit tightly over, and it can shift around and feel uncomfortable. "It's much trickier than putting on a male condom," says Dr. Shirazian. "The package does describe application, but it's not easy, honestly. Female condom rates of success are lower and not a very popular method for that reason."
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22 pregnancies per 100 women in a year
The birth control method most of us know as pulling out is officially called the withdrawal method—a man withdraws his penis right before ejaculation, so no sperm enter the vagina. But it's not exactly effective, hence its other nickname, "pull and pray."
If just a little bit of ejaculate gets in or near the vagina during the withdrawal process, pregnancy is possible—which means your partner has to display some serious control to pull out at the right time. While there isn't exactly great research on the topic of getting pregnant from pre-ejaculate, at least one study found , Dr. Wu points out.
"I try to counsel people based on their current emotions about pregnancy and becoming a parent," Dr. Wu says. If pregnancy isn't in the cards for right now, "I move toward more effective methods," she says. If women are more open to becoming pregnant and are happy using the withdrawal method (and aren't at risk for STDs), "I just may emphasize the best way to use withdrawal." And that means, she says, doing it right—every single time.
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24 pregnancies per 100 women who have given birth before in a year;12 in women who have never given birth before
Like a diaphragm, the sponge, made of squishy plastic, covers your cervix and blocks sperm. It also contains spermicide to immobilize or zap those swimmers if they happen to get close. You can leave it in for up to 24 hours—but it has to stay in place for at least six after having sex to be effective.
Like other methods that you insert yourself, this one has to be placed properly. As evidenced by the effectiveness stats, it might not fit so perfectly if you’ve given birth in the past. Because the sponge isn't among the most popular forms of contraception, Dr. Wu says it might also require a little extra work to track one down online or at a local pharmacy.
If you’re super organized and ultra-committed to your period tracking app, you might consider a fertility awareness method, also sometimes called natural family planning or the rhythm method. This involves keeping close track of your period and ovulation so you know when you’re most fertile—and don't having sex (or using another method of birth control) on those days.
Women opting for a fertility awareness method (or FAM) might take their temperature every morning, check their cervical mucus every day, or chart their cycles (or use any combination of these three methods) to determine when they’re near ovulation. Keep in mind that this works best for women whose cycles are pretty predictable, so they can track these changes and follow the patterns, Dr. Wu says. "I think it can be a good method for people with a regular cycle who are motivated to do it." For everyone else, you have almost a one in four chance of becoming a parent.
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28 pregnancies per 100 women in a year
Spermicide should always be used with a diaphragm, and it can increase the effectiveness of condoms (which is why many condoms are coated with spermicide already). But it can also be used on its own to slow down sperm and help block the cervix. You can find spermicide in creams, gels, films, foams, or suppositories. No matter what form you go with, however, you’ll need to insert the spermicide right before having sex—and be comfortable with the fact that on its own, it's the least effective birth control method available.
f you're going to use spermicide, Dr. Wu recommends choosing the film form. The tiny sheets dissolve in the vagina. "It's really small, partners won't even know it's there," she says.