Birth Control: Rhythm Method (Fertility Awareness)

What is fertility awareness?

Key points

  1. The rhythm method of birth control is also known as the fertility awareness method (FAM).
  2. FAM involves tracking your menstrual cycles to learn when you’re fertile.
  3. It’s one of the least reliable forms of birth control.

The fertility awareness method (FAM) is a strategy that women can use to help prevent pregnancy. It involves tracking your natural cycle of fertility, or your menstrual cycle.

FAM is also commonly known as:

  • the rhythm method
  • periodic abstinence
  • natural family planning

In FAM, you abstain from sex during your most fertile days. Alternately, you can use backup contraception on your fertile days. The effectiveness of FAM varies from one type of FAM to another. In general, it’s one of the least reliable forms of non-abstinence-based birth control.



How does the fertility awareness method work?

If you’re a premenopausal adult woman, you’re most likely to be fertile and get pregnant if you have unprotected sex right before or during ovulation.

Ovulation happens when your ovaries release an egg. It occurs approximately once per month, about 12 to 16 days after menstruation. The specific day on which you ovulate depends on your cycle length. This is largely controlled by fluctuations in your sex hormone levels. For some women, these fluctuations are quite consistent from one month to another. Other women have more irregular menstrual cycles.

Once an egg is released from your ovaries, its lifespan is very short. Conception can only occur if it’s fertilized 24 to 48 hours after the time of actual ovulation. However, male sperm can remain alive and viable in your body for up to five days after ejaculation. So, it’s possible to have intercourse up to five days before you ovulate and get pregnant as a result.

These biologic realities mean the actual period of viable fertility can last anywhere from five to eight days for most women. In general, women are most fertile during the following times:

  • five days before ovulation
  • the day of ovulation
  • within 12 to 24 hours after ovulation

You’re less likely to get pregnant if you’ve accurately identified your fertile period and avoid unprotected sex on those days each month. In theory, this will prevent viable sperm from being present in your fallopian tubes at the same time as a viable egg. In turn, this will prevent fertilization and conception. That being said, fertility awareness is among the least reliable methods of contraception.



How can you track your menstrual cycle?

Every woman’s menstrual cycle is different. To use FAM effectively, it’s important to pinpoint when you’re ovulating. There are several ways to track your ovulation cycle and fertility.

These are some common methods of fertility awareness:

  • Calendar method: You use past menstrual cycles to estimate the time of your ovulation. This is the least reliable method of fertility and should be avoided if your menstrual cycles are shorter than 26 days or longer than 32 days.
  • Temperature method: You track your basal body temperature (BBT) for several cycles by using a very sensitive thermometer to take your temperature before you get out of bed each morning. Due to hormonal surges, your BBT goes up right after ovulation.
  • Cervical mucus method: You track the color, thickness, and texture of your cervical mucus to monitor your fertility. Your cervical mucus becomes thinner when you ovulate.

Another option is the symptothermal method, in which you use all three of the methods above together. Combining methods makes FAM more effective. You should track at least six to 12 menstrual cycles before you begin to rely on FAM for contraception.

It’s best to talk to your doctor or take a course on fertility awareness before deciding if FAM is right for you. FAM requires a significant and consistent investment of time and effort.



How effective is the fertility awareness method?

The effectiveness of FAM depends on:

  • which fertility tracking method you use
  • how regular your menstrual cycles are
  • how reliably you track your menstrual cycles
  • how long you abstain from sex around your ovulation date

FAM can be effective for couples that always use it consistently and correctly. That can be hard to do. Among women who use FAM inconsistently or incorrectly, 24 out of 100 become pregnant each year, reports Planned Parenthood. That makes it one of the least reliable methods of non-abstinence-based birth control.



What are the benefits of the fertility awareness method?

FAM has several advantages. For example, it:

  • costs very little
  • is safe to use
  • requires no medication
  • produces no side effects
  • can be stopped easily and immediately if you decide you want to get pregnant

Practicing FAM can also help you and your partner learn about fertility. This may help you get pregnant later on, if you so choose.



What are the disadvantages of the fertility awareness method?

FAM doesn’t protect against sexually transmitted infections (STIs), such as chlamydia, herpes, or HIV. It also has a number of other disadvantages. For example:

  • you need to consistently track your menstrual cycles for at least six months before the method can be considered reliable
  • you need to abstain from sex or use backup contraception during your fertile days
  • both members of the couple must be involved in the process
  • it has a higher failure rate compared to many other forms of birth control, such as condoms, diaphragms, and birth control pills

If you have irregular menstrual cycles, FAM is a poor choice for you. Talk to your doctor to learn more about different birth control options.

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