Rhythm Method: Can It Prevent Pregnancy?

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When it comes to preventing unwanted pregnancy, there are a variety of birth control options, each with their own pros and cons. From condoms to birth control pills to IUDs, there's a range of choices, effectiveness, and side effects.

You might have also heard about one such form of birth control called the rhythm method, which consists of abstaining from sex or using a barrier method on the days of the month that you are most likely to get pregnant.

These days are identified by tracking your menstrual cycles and watching for signs of ovulation. "To use the rhythm method, you track your menstrual history to predict when you will ovulate," says Cynthia M. Murdock, MD a fertility specialist at Illume Fertility who is board-certified in obstetrics and gynecology, and in reproductive endocrinology and infertility. "This can help determine when you're most likely to conceive if you have regular cycles."

The biggest issue with the rhythm method is that menstrual cycles can vary in length from month to month, sometimes unexpectedly. This makes it less reliable than other forms of birth control, so before you choose this strategy, there are some important things to keep in mind.

What Is the Rhythm Method?

The rhythm method aims to prevent pregnancy by identifying the fertile days in your cycle so that you can stop sperm from meeting egg during this time.

"Fertility window is a six-day period of time during your cycle, for the five days leading up to ovulation (the day your egg is released) and the 24 hours after," says Dr. Sam Rahman, a board-certified OB/GYN and Clinical Assistant Professor of OB/GYN at Northwestern Feinberg School of Medicine in Chicago.

Let's break that down a bit. A typical menstrual cycle is 28 days long. It is made up of four distinct phases: the menstrual phase, the follicular phase, ovulation, and the luteal phase.

Days one through five are typically menstrual bleeding. Next comes the follicular phase, when an egg matures in your ovaries. The mature egg is then released into your uterus (ovulation), where it can potentially be fertilized by a sperm, resulting in pregnancy.

The next two weeks are the luteal phase, during which the uterine lining builds and prepares for pregnancy. But, if fertilization does not occur, the body sheds the egg and the lining during menstruation, and the process starts anew.

Ovulation typically happens around day 14 of your cycle, with the egg remaining in your uterus for about 24 hours before it is no longer able to be fertilized. Sperm usually live for about 48 hours in the body, but they can live up to five days.

This would mean that, assuming that you have a typical 28-day cycle, to prevent fertilization, you would need to abstain from sex from day nine through day 16.

How Successful Is the Rhythm Method?

One study found the rhythm method to be as effective as 98% with perfect use, but only 76% effective with typical use, meaning that the rhythm method is significantly less effective than traditional birth control for most people.

"Achieving 'perfect use' of the rhythm method can be difficult, as it requires constant tracking of your menstrual cycle and a commitment to the method from both partners," notes Dr. Murdock.

The rhythm method can be reliable for some people, particularly those with very regular menstrual cycles who have the time to meticulously track their ovulation symptoms. But, only a fraction of menstruating people will have a precise 28-day cycle, every time.

Many people experience cycles as short as 23 days and as long as 35 days—or even longer. Within these cycles, the date of ovulation won't always be the same either.

If you track your menstrual cycle for six months, you can get an idea of your cycle's length. Subtracting 14 from the length of your cycle will help you estimate which day you ovulate on. But, it's rare for anyone's menstrual cycle to be exactly the same length every month. Additionally, ovulation is variable and external factors like stress or illness may push it back unexpectedly.

Let's say you have a 28-day cycle and you abstain from sex from days nine through 16, but you end up ovulating on day 16 (just two days later than the typical day). You could conceive on day 17 in this case.

If instead, you ovulate on day 12 (just two days earlier than the typical day), sex on days seven or eight could get you pregnant, since sperm can live up to five days in your body.

The rhythm method may offer some protection against pregnancy, but it is important to note that it does not offer any protection against sexually transmitted infections (STIs) unless coupled with condoms.

Who Is the Rhythm Method For?

You might consider the rhythm method if you do not want to use hormonal birth control due to side effects, costs, medical advice, or personal beliefs.

The rhythm method may also be the right choice for you if you have an extremely regular period. If you are very data-driven and you know you can take the time to methodically track your cycles and take detailed notes of your fertility clues each month, then it could potentially be a reliable form of birth control for you.

Remember though, there is still a margin for error with the rhythm method. You should be comfortable with the possibility of getting pregnancy unexpectedly if you use this method, and it's worth talking through with your OB/GYN or healthcare provider as well.

Drawbacks of the Rhythm Method

There are a few reasons why the rhythm method might not be the best choice for some people. This method takes constant tracking and paying attention to which day of your cycle you're on. The method fails most often when it is not used consistently and correctly.

The rhythm method is also different from many other forms of birth control because it requires you to abstain from intercourse on certain days. This can be almost 50% of the time. If that doesn't seem practical to you, it might be wise to choose another method.

Combining the Rhythm Method With Fertility Awareness

The rhythm method is considered outdated because it does not apply to a wide range of people. If everyone had a perfectly regular cycle, it might be much more reliable.

However, there is a similar form of birth control called the Fertility Awareness Method (FAM), that helps you pinpoint ovulation so you can more accurately avoid pregnancy.

To use FAM, you combine clues your body gives, like differences in cervical mucus and body temperature to figure out when you're ovulating. However, the only way to know for sure that you have ovulated is when it has already happened, so you would need to abstain from intercourse or use a barrier method for about half the month or more.

A Word From Verywell

The rhythm method is practiced by abstaining from intercourse or using a barrier method on your fertile days. Find your fertile window by tracking your cycles to find out your typical cycle length. Then subtract 14 to estimate when ovulation will occur. Cross check this estimation by checking your fertility signs. Skip intercourse for five days leading up to ovulation and an additional 24 hours after.

If you are up to keeping track of your data, the rhythm method might work for you, especially if you don't want to use hormonal birth control or barrier methods. But it's essential to be aware that ovulation can be unpredictable, and you could become pregnant.

Please also keep in mind that, unless paired with condoms, the rhythm method does not protect against STIs. If you have questions or are considering using the rhythm method, please talk with your OB/GYN or healthcare provider.

6 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kaiser Family Foundation. Natural family planning as a means of preventing pregnancy.

  2. Munster K, Schmidt L, Helm P. Length and variation in the menstrual cycle-a cross-sectional study from a Danish county. BJOG:An international journal of O&G. 1992;99(5):422-429. doi: 10.1111/j.1471-0528.1992.tb13762.x.

  3. Reed BG, Carr BR. The normal menstrual cycle and the control of ovulation. In: Feingold KR, Anawalt B, Boyce A, et al., eds. Endotext. MDText.com, Inc.; 2000.

  4. Frank-Herrmann P, Heil J, Gnoth C, et al. The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple’s sexual behaviour during the fertile time: a prospective longitudinal study. Human Reproduction. 2007;22(5):1310-1319. doi: 10.1093/humrep/dem003.

  5. Wilcox AJ. The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study. BMJ. 2000;321(7271):1259-1262. doi: 10.1136/bmj.321.7271.1259.

  6. Grimes DA, Gallo MF, Halpern V, Nanda K, Schulz KF, Lopez LM. Fertility awareness-based methods for contraception. Cochrane Fertility Regulation Group, ed. Cochrane Database of Systematic Reviews. 2004;2012(5). doi: 10.1002/14651858.CD004860.pub2.

By Elisa Cinelli
Elisa is a well-known parenting writer who is passionate about providing research-based content to help parents make the best decisions for their families. She has written for well-known sites including POPSUGAR and Scary Mommy, among others.