Does This Controversial Birth Control Method Actually Work?

If it feels like you've tried every type of birth control out there and still haven't found something that works for you, then the prospect of an inexpensive, non-hormonal, at-home method probably sounds pretty ideal. And yes, this type of birth control actually exists, but there's kind of a catch.

Called the "rhythm method," this fertility awareness form of birth control involves tracking your period to calculate when you ovulate, according to Planned Parenthood. It's been around since the 1930s, but it's making a comeback both with people who are seeking an alternative to hormonal birth control, and those trying to get pregnant.

In general, doctors tend to be skeptical about the rhythm method for birth control, simply because in actual use, it's not as accurate or effective as other methods available, explains Margaret Polaneczky, MD, FACOG, an Ob/Gyn at NewYork-Presbyterian/Weill Cornell Medicine. In fact, there's a joke that Dr. Polaneczky likes to tell: "What do you call people who use the rhythm method for birth control?" The answer: "Parents."

Now, this isn't to say that no one should be using the rhythm method, but it requires diligence and really only works for those with a very regular cycle lasting between 26 and 32 days, she says. If you think that might be you, grab a calendar and a calculator, and let's get into how this method works.

First, record the length of six to 12 of your menstrual cycles, from the first day of your period to the first day of your next period, according to the Mayo Clinic. Then, you take the length of your shortest menstrual cycle, and subtract 18 from the number of days to find the first fertile day of your cycle. Next, take the length of your longest menstrual cycle and subtract 11 from the number of days to determine the last fertile day of your cycle. Now that you have this information, you have to plan sex around when you're most fertile — either going hard during those days, if you're trying for a baby, or keeping pants firmly in place if not. To ensure accuracy, it's best to keep updating your calculations every month.

The rhythm method makes it possible to zero in on the days around ovulation, when the egg is released and it's possible to become pregnant. If an egg isn't fertilised right at this time, then it gets reabsorbed into the body, preempting the next period. So you can see why timing is so important.

There's another way to use this method, either instead of or in addition to fastidiously counting days: tracking the changes in your cervical mucus throughout your cycle, according to Planned Parenthood. When someone is about to ovulate, their vaginal mucus is typically thin, clear, and sticky compared to the other days. In general, it's "safest" to have sex after the clear mucus goes away, and it becomes cloudy and sticky again. This method requires checking and charting details about your discharge on a daily basis, so even with proper use, it might not be the most accurate birth control method. After all, the quality of discharge is subjective.

There are a few ways to make the rhythm method easier to follow, including calendars, apps, or even a tracking accessory, like CycleBeads, a bracelet with colour-coded beads that indicate the days in your cycle when you're most fertile. A 2002 study found that CycleBeads are 95% effective in preventing pregnancy, but that study only included women who all had very regular cycles, and avoided sex completely during their fertile days, Dr. Polaneczky says. "In practice, couples tend to have sex during this time, but use a condom or withdrawal, which has a pregnancy risk." As you can imagine, this method — whether you're using beads, an app, or your own memory to track your dates — isn't perfect, because not everyone has a precise or regular menstrual cycle.

In countries that don't have access to modern contraception, there's strong support for using the rhythm method, Dr. Polaneczky says. And even in areas where there is access, the fact that this method involves no hormones, no medication, and no barrier makes it attractive to some people. It's a bit of a gamble, so you "have to accept the true efficacy of this, which is probably somewhere in the mid-80% range," she says. For that reason, she recommends it for people who are trying to find out when they're most fertile, so they can get pregnant, as opposed to those trying to prevent pregnancy.

The thing that you have to remember about birth control is that there's no one-size-fits-all approach, because everyone's body and lifestyle is different. If you find that the rhythm method works for you, go for it, but understand that there might be a risk — or the bonus — of you ending up pregnant.