Rhythm Method

The rhythm method is a form of natural family planning to help identify when a person is ovulating. It’s done by tracking a person’s menstrual cycles on a calendar to either avoid or engage in sexual intercourse during a person’s fertile days.

What is the rhythm method of birth control?

The rhythm method is a type of birth control that involves tracking your menstrual cycle. This form of birth control involves tracking your menstrual cycle on a calendar to predict ovulation. You use this information to identify when you’re most fertile. When you’re fertile, you avoid sexual activity or use other types of birth control at that time of your cycle. It can also help couples know when to have sex if they wish to become pregnant. The rhythm method is sometimes called “the calendar method” because it involves tracking your cycle on a calendar. When used alone, it’s not a very reliable form of contraception. It’s a type of “natural family planning” or “fertility awareness.”

How does the menstrual cycle work?

A typical menstrual cycle is between 28 and 32 days. The day your period starts is considered the first day of your cycle. Ovulation typically occurs around day 14.

When you ovulate, your ovary releases an egg. This egg travels from your ovary and through your fallopian tube, where sperm can fertilize it and create a pregnancy. If a pregnancy doesn’t occur, you’ll get your period (or menstruate) about 14 days after ovulation.

If you wish to track your menstrual cycle, a good place to start is marking the first day of your period on a calendar. You count the number of days it takes to get your period each month. For example, if you start your period on March 1 (day one) and then get your period again on March 30, there are 29 days in your menstrual cycle. March 30 is day one of your next cycle, and you begin the tracking process again.


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Why is it called the rhythm method?

The word “rhythm” describes a cadence or a predictable pace. The rhythm method of birth control describes your body’s natural rhythm or the rhythm of the calendar.

How effective is the rhythm method for birth control?

The rhythm method is effective 75% of the time. It isn’t as effective at preventing pregnancy as other methods, such as taking birth control pills or using an intrauterine device (IUD). The effectiveness depends on how consistent you are about tracking your cycle and your commitment to avoiding sex or using birth control when you’re fertile.

It also shouldn’t be used if your cycle is fewer than 26 days or longer than 32 days.


How does the rhythm method work?

You’re only fertile (or able to get pregnant) for a few days each month. People using the rhythm method analyze their past menstrual cycles to determine their fertile days. They can then choose not to have sex during those days or use a barrier form of birth control, such as condoms or spermicide.

There are several ways to monitor fertility. The most common approach used in the rhythm method involves knowing how long your cycles are and then using that information to determine when you’re ovulating.

Most people will have a period 14 to 16 days after ovulation, regardless of the length of their overall cycle. Although eggs are only available for fertilization for about 24 hours after being released from your ovaries, sperm can live for five days. For that reason, people using the rhythm method should avoid sexual intercourse for at least five days before and three days after ovulation.

Generally speaking, you’re most fertile:

  • In the days just before ovulation.
  • The day of ovulation.
  • Within 24 hours of ovulation.

The longer you keep track of your cycle, the more clearly you’ll see a pattern. Once you identify your cycle length and a window for when ovulation generally occurs, you can avoid unprotected sex on those days of each menstrual cycle.

How do I calculate my rhythm method safe days for sex?

You can use the steps below to find your fertile days. During the fertile days of your cycle, you should avoid unprotected sex.

  • Day one is the first day you menstruate (or get your period). Mark this on a calendar with an X.
  • Mark the first day of your next period with an X.
  • The number of days between the X's is the length of your cycle.

Plan on tracking your menstrual cycle on a calendar for at least six months before you use the rhythm method as birth control.

When you’ve tracked your cycle for six months, take the following steps:

  • Find the longest and shortest cycles from your calendar. For example, the longest might be 31 days, and the shortest might be 28.
  • To find the first day of your fertility window, subtract 18 from your shortest cycle. If your shortest cycle was 28 days, subtract 18 from 28, which gives you 10. That means the first day you are fertile is the 10th day of your cycle.
  • To find the last day of your fertility window, subtract 11 from your longest cycle. If 31 was your longest cycle, subtract 11 from 31. This means the 20th day of your cycle is when your fertile window ends.
  • Using this example, you would abstain from sex or use protection on days 10 through 20 of your menstrual cycle.

Keep in mind that you can’t get pregnant on all days of your fertility window. However, your fertile window is unsafe for unprotected sex because there’s a chance you could become pregnant during this time. Conversely, if you want to get pregnant, you’d have sexual intercourse as much as possible during your fertile window.

Remember, using the rhythm method alone isn’t super reliable. If you combine a calendar method with other natural family planning methods, you may have a better chance of pinpointing exactly when ovulation occurs.


What is the standard days calendar method?

The standard days method is a variation of the rhythm method that works best for people who consistently have menstrual cycles that lasts between 26 and 32 days. In the standard days method, you’re considered fertile on days eight through 19 of every menstrual cycle. You avoid sexual intercourse or use a barrier method on those days every cycle.

How can I track my fertility naturally?

There are other methods to track fertility, and they often work best for determining ovulation when used with one another. Some other approaches you can use to track your fertility other than a calendar method are:

Cervical mucus

Your cervical mucus changes throughout your menstrual cycle. It becomes stretchy and clear during ovulation, similar to an egg white. People using the cervical mucus method check their mucus daily and record what they find. Over time, they’ll likely see a pattern of when it changes, revealing their fertile times. The cervical mucus can be affected by many things, such as breastfeeding, taking birth control pills, having a sexually transmitted infection (STI) or having a prior surgery on your cervix.

Basal body temperature

Another way to monitor fertility is to take your temperature first thing each morning (before even sitting up in bed) with a thermometer that measures basal body temperature. The thermometer needs to display a measurement that reads two decimal points. When you ovulate, your temperature rises 0.4 to 1 degree Fahrenheit (or -17.55 to -17.22 degrees Celsius). Chart your temperature on paper (there are many charts available online) so you can identify a pattern. You’ll notice your temperature stays consistent before sharply increasing after ovulation. Your temperature drops again just before your period. You should avoid unprotected intercourse for five days before a basal body temperature increase. You can resume sexual intercourse the day after the temperature spike.

Cervical changes

Checking your cervix for physical changes, including a softer texture, higher position and increased opening, can also signify ovulation.

Ovulation kits

You can purchase an ovulation kit or ovulation testing strips at your local grocery store. These at-home ovulation tests work by detecting specific hormones in your pee (like at-home pregnancy tests). Follow the directions on the packaging for the most accurate results.

Physical changes

Some people can sense when they’re ovulating because their body feels different. For example, some people experience breast tenderness or dull pain on their ovary during ovulation. It’s best to not just rely on physically “feeling” like you’re ovulating and combining this with other methods.

What if I realize I have made a mistake and had unprotected sex during my fertile time?

Emergency contraception medications are available in most drugstores today. Plan B One-Step® and generic versions don’t require a prescription, but some other types of emergency contraception do. All types work best if taken as soon as possible. Some may still be effective up to five days after having unprotected sex.

If you’re using the rhythm method as your primary source of birth control, you might want to ask your healthcare provider ahead of time about emergency conception.

Why do people use the rhythm method for contraception?

The rhythm methods and other fertility awareness methods appeal to people who:

  • Don’t want the side effects of birth control.
  • Have religious objections to using medical forms of birth control.
  • Don’t want to take artificial hormones.
  • Want the ability to reverse or stop birth control quickly.
  • Desire a free or inexpensive form of birth control.
  • Don’t want to use implantable devices, pills, prescriptions or deal with office visits.

What is the biggest drawback to using the rhythm method?

The biggest drawback is that it’s not as effective in preventing pregnancy as other birth control methods. It requires you to be diligent in tracking and recording your cycle, and even then, it can be hard to be 100% sure what days you’re fertile. Some of the other cons of the rhythm method are:

  • It can be annoying to record and track your cycle every day.
  • No protection against sexually transmitted infections (STIs).
  • Challenging for people with irregular periods.
  • Requires abstinence or a backup method for about 10 days per menstrual cycle.
  • It takes several months of monitoring to have a clear pattern of when you’re fertile.
  • Offers no relief of pain associated with your period like other birth control medications provide.

What are the benefits to using the rhythm method?

One benefit of the rhythm method is that it’s free and doesn’t require a prescription. Also, if you do decide you want to have a baby later, you can start trying right away.

Another benefit is avoiding the possible side effects of other methods, such as pills, patches, shots or implanted devices. While these side effects are minor for most people, they can include:

  • Bleeding between periods or missed periods.
  • Weight gain.
  • Mood changes.
  • Sore breasts.
  • Headaches.
  • Skin irritation.
  • Nausea.
  • Pain or infection at the insertion site for implanted devices.
  • Difficulty removing an implant.
  • Ovarian cysts.
  • Increased blood pressure.
  • Increased risk of blood clots, stroke and heart attack.
  • Allergic reactions.

What are my other options for birth control?

There are many options available today for birth control. These include:

  • Abstinence: Not having sex is 100% effective in preventing pregnancy.
  • Barrier methods: These stop sperm from reaching an egg. Options include condoms, spermicides, diaphragms, sponges or cervical caps. These options are up to about 88% effective. Combining these methods increases their overall effectiveness.
  • Long-acting reversible contraceptives: These are birth control options that your provider inserts into your body, such as intrauterine devices (often called IUDs) and hormonal implants. They can last up to a few years. When used correctly, long-acting contraceptives are about 99% effective.
  • Short-acting hormone treatments: You have to take or use these birth control options daily, monthly or quarterly. Examples include birth control pills, patches, shots or a vaginal ring. These options can be up to 94% effective.
  • Sterilization: These procedures include tubal ligation or a vasectomy. They’re almost 100% effective.

How can I learn more about natural family planning methods?

Most healthcare professionals can talk to you about natural family planning methods or nonmedical birth control methods. Your gynecologist or primary care provider is a good place to start. The more you know about this approach to birth control, the better your results will be.

What is the Catholic rhythm method?

The Catholic rhythm method is the same as the rhythm method. In 1930, a Catholic physician used the rhythm method to help couples avoid pregnancy. The rhythm method of birth control was initially popular with Catholic couples and is often associated with that particular religion.

A note from Cleveland Clinic

If you’re interested in natural forms of birth control, the rhythm method might be for you. While it’s not as reliable as hormonal or barrier forms of contraception, it can help you predict when you’re fertile. For it to be effective, you must be diligent about tracking your menstrual cycle and either avoid sex or use protection around the time of ovulation. The rhythm method works best when it’s used in conjunction with tracking your basal body temperature or monitoring your cervical mucus. Talk to your healthcare provider about your goals for birth control so they can help you decide what’s best for you.

Medically Reviewed

Last reviewed on 08/12/2022.

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