The woman’s body is not always fertile and at risk for pregnancy. In fact, there are several days a month when pregnancy is extremely unlikely. Rhythm Methods (also known as Fertility Awareness Methods) take advantage of the natural cycle of fertility as a birth control method. 

What Is It?

The Rhythm Method is a way of preventing pregnancy by understanding the body’s natural ovulation cycle and abstaining from sex during a woman’s most fertile days. The Rhythm Method is also known as natural family planning, the fertility awareness method, or periodic abstinence.

How Does It Work?

A woman is most likely to get pregnant during ovulation, when the egg is released into the ovaries, which occurs once on month about 12 to 16 days after menstruation. Because sperm can live up to five days in the reproductive tract, a woman is most fertile five days before ovulation, the day of ovulation, and sometimes a day or two after ovulation. If unprotected sex is avoided on those seven days surrounding ovulation, pregnancy is less likely because there is not an egg for the sperm to fertilize.

How Do I Use It?

Every woman’s menstruation cycle is different, so it is important to pinpoint exactly when you are ovulating in order for this method to be effective. There are several ways to keep track of fertility. You can use past menstrual cycles to estimate when you are most fertile and mark a calendar when it is safe to have sex. This is called the calendar method or rhythm method. Another method is cervical mucus monitoring or the Billings method. Measuring the consistency and amount of cervical mucus can help you determine when ovulation will occur, as the cervical mucus is most prevalent during and just before ovulation. It is best to talk to your doctor or take a course on fertility awareness before deciding if this is a birth control method that is right for you. 


Rhythm Methods are on average 75 to 88 percent effective in preventing pregnancy, but success depends on how well the methods are used. Using multiple methods to determine when ovulation occurs can improve effectiveness.  


Rhythm Methods are inexpensive, safe, and don’t require any medical devices or medication. There are no side effects to these methods. Understanding and charting ovulation can also help a couple get pregnant when desired, by educating both partners about when the woman is most fertile.


This form of birth control does not protect against sexually transmitted diseases. In order for Fertility Awareness Methods to be effective, both partners need to be involved in the process. If you have more than one sex partner or cannot abstain from sex during your fertile days, the these methods may not be right for you. In addition, some women have difficulty accurately tracking ovulation because of irregular periods.