The fertility awareness method and the rhythm method are two different forms of nonhormonal birth control. Both involve tracking your natural cycle of fertility.
The fertility awareness method (FAM) is a natural family planning strategy that can be used to help prevent pregnancy.
It involves tracking your natural cycle of fertility and your menstrual cycle, developing a better awareness of your body, and using a variety of non-pharmaceutical methods to detect ovulation.
The rhythm method is where your previous menstrual cycles are tracked on a calendar, and this information is used to predict future ovulation dates. FAM combines the rhythm method with even more attention to the body to better predict ovulation and prevent pregnancy.
In the rhythm method and in FAM, you abstain from sex (periodic abstinence) during your most fertile days. Alternately, you can use backup contraception on your fertile days.
The effectiveness of FAM varies depending on the combination of tracking used. There are many ways to prevent pregnancy that are more effective than a natural method. They involve medication or medical intervention.
FAM is one of the least reliable forms of pregnancy prevention. But it can be an appropriate choice of birth control for those who are diligent and self-aware.
You’re most likely to be fertile and get pregnant if you have contraception-free sex a few days 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 you ovulate depends on your cycle length. This is largely controlled by fluctuations in your sex hormone levels.
For some, these fluctuations are quite consistent from one month to another. Others have more irregular menstrual cycles. A period occurs 11 to 14 days after ovulation if a pregnancy hasn’t occurred.
Once an egg is released from your ovaries, its life span is very short. Conception can only occur if the egg is fertilized 12 to 24 hours after the time of actual ovulation.
However, sperm can remain alive and viable in the body up to 5 days after ejaculation. So, it’s possible to have intercourse up to 5 days before you ovulate and get pregnant as a result.
These biologic realities mean the actual period of viable fertility can last anywhere from 5 to 8 days. In general, you’re most fertile during the following times:
- the 5 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 contraception-free sex on those days each month.
Theoretically, this will prevent viable sperm from being present in your body 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. Multiple methods of collecting information are necessary. You can use the calendar method, the temperature method, and the cervical mucus methods to increase the effectiveness of FAM.
Menstrual cycles are unique from person to person. To use FAM effectively, it’s important to pinpoint when you’re ovulating. There are several ways to track your ovulation cycle and fertility. Using a combination of the following improves effectiveness in preventing pregnancy.
These are some common methods incorporated into fertility awareness:
- Calendar rhythm method. In this method, you use past menstrual cycles to estimate the time of your ovulation. When used on its own, this is the least reliable method of birth control. It should be avoided if your menstrual cycles are shorter than 26 days or longer than 32 days.
- Temperature method. Here, you track your basal body temperature (BBT) for several cycles by using a very sensitive basal thermometer to take your temperature before you get out of bed each morning. Due to hormonal surges, your BBT goes up 3 to 4 days after ovulation. BBT should not be used to predict ovulation in real time. It’s a retrospective tool to help someone determine whether or not they ovulated that cycle.
- Cervical mucus method. In this method, you track the color, thickness, and texture of your cervical mucus to monitor your fertility. Your cervical mucus becomes thinner, slippery, and stretchy when you ovulate. Tracking your cervical mucus will require some practice.
The symptothermal method, in which you use all three of the methods above together, makes FAM most effective. You should track at least 6 to 12 menstrual cycles before you begin to rely on FAM for contraception.
It’s best to talk with your doctor or take a course on fertility awareness before deciding if FAM is right for you. Educate yourself about your body and its cycles. FAM requires a significant and consistent investment of time and effort.
But it can also be a great and effective choice for those who are willing to invest the time and understanding.
The effectiveness of FAM depends on:
- which fertility tracking method(s) 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 who always use it consistently and correctly. That can be hard to do. Among those who use FAM inconsistently or incorrectly, up to 24 out of 100 become pregnant each year, according to Planned Parenthood.
That makes it one of the least reliable methods of nonabstinence-based birth control.
FAM has several advantages. For example, it:
- is inexpensive
- 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.
FAM doesn’t protect against sexually transmitted infections (STIs), such as chlamydia, herpes, or HIV. It also has a number of other disadvantages.
- You need to consistently track your menstrual cycles for at least 6 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.
- FAM has a higher failure rate compared with many other forms of birth control, such as condoms, diaphragms, and birth control pills, patches, or injections. But if used correctly, it can be just as effective.
If you have irregular menstrual cycles, FAM may be a poor choice for you. Talk with your doctor to learn more about birth control options.