• Text Resize A A A
  • Print Print
  • Share Share Share Share

Natural Family Planning and Fertility Awareness

Quick Facts

Effectiveness in Preventing Pregnancy

  • Of 100 couples each year that use natural family planning methods, such as fertility awareness, up to 25 women may become pregnant.
  • Fertility awareness-based methods alone have a one in four chance of leading to an unintended pregnancy. However, this approach can be effective if the instructions are followed carefully for each menstrual cycle.
  • It can be an effective type of birth control if more than one method is used, and if the methods are used correctly. Additional methods may include practicing abstinence or using condoms or other barrier methods during potentially fertile times of the menstrual cycle.
Track fertility signs.No STD protection.No office visit required but encouraged.

What is fertility awareness?

Fertility awareness-based methods help women and couples become more familiar with the signs of ovulation and the pattern of the menstrual cycle to understand how to plan sexual activity and avoid pregnancy or become pregnant. A woman learns to recognize the specific signs of her fertile days—the days during each month that she is most likely to become pregnant (conceive)—and either does not have sex during these days, or uses a birth control method like condoms.

Several fertility awareness-based methods rely on information about the timing of a woman’s menstrual cycle, changes in her cervical fluid, and/or her basal body temperature.

  • A menstrual cycle is counted from the first day of bleeding in one month to the first day of bleeding the next month (usually 23-35 days). The most fertile time is when ovulation occurs, usually in the middle of the menstrual cycle.
  • Cervical fluid (healthy vaginal discharge) changes throughout each menstrual cycle. After each menstrual period ends, there may be no noticeable cervical fluid in the vaginal area. These are “dry” days. As ovulation approaches (and a person becomes more fertile), the fluid becomes more wet and stretchy (like egg white).
  • Morning body temperature rises within about 12 hours of ovulation and stays at this slightly higher range until around the time of the next period.

The following fertility awareness-based methods use a calculation to identify the fertile days:

  • Standard Days Method using CycleBeads: based on statistical information about women who have regular menstrual cycles, you can use this method if your cycle is between 26 and 32 days long. Counting from the first day of a period, days eight through 19 of the menstrual cycle are considered fertile days.
  • Calendar Rhythm Method: count and record days in each menstrual cycle for six months and predict future fertile days (days when pregnancy can occur) using a standard calculation.

The following fertility awareness-based methods rely on observing bodily changes:

  • TwoDay Method: track cervical fluid every day, twice a day. A woman is considered fertile when she has secretions that become more wet and stretchy on either that day or the day prior.
  • Ovulation Method: observe and chart cervical fluid and identify fertile days.
  • Symptothermal Method: observe and record cervical fluid as well as changes in basal body temperature.

The Lactational Amenorrhea Method (LAM) is another form of natural birth control. This method is for new mothers who feed their babies only breastmilk for up to six months and having no periods or spotting during that time. Women considering LAM should get counseling from a healthcare provider to make sure it is the right choice for their lifestyle, as well as to plan for a new form of birth control as soon as breastfeeding frequency decreases or solid foods are introduced.

How effective is fertility awareness?

Of 100 couples who use natural family planning methods each year, up to 25 women may become pregnant. Couples using more than one fertility awareness-based method correctly will increase their ability to identify fertile days accurately.

  • The effectiveness of using fertility awareness-based methods for pregnancy prevention depends on using the method correctly and consistently. Because there are various approaches to fertility awareness methods, the effectiveness rates vary.
  • These methods can be effective if the instructions are followed carefully for each menstrual cycle. Fertility products are available to help keep track of the changing fertility signs.
  • If preventing pregnancy is a high priority, more effective methods (for example, an IUD or implant) of birth control should be considered.

Advantages of Fertility Awareness-based Methods

  • Fertility awareness-based and natural family planning methods can increase awareness and understanding of one’s body.
  • These methods are safe and reasonably effective in preventing pregnancy when used correctly.
  • These methods can help you avoid pregnancy.  They can also work if you want to become pregnant by helping to predict which days you are most fertile.
  • Couples may develop greater communication and cooperation using these methods.  The methods are more effective with cooperation between sexual partners.
  • These methods are relatively inexpensive and do not require an office visit, although it is a good idea to discuss your plan with a healthcare provider.
  • Fertility awareness and natural family planning have no side effects and do not cause problems with using medication.

Drawbacks of Fertility Awareness-based Methods

  • Fertility awareness-based methods requires cooperation and commitment from both partners to either abstain from sex or use contraception during fertile days.
  • These methods do not protect against sexually transmitted diseases (STDs), including HIV.  Always use a condom to reduce the risk of STDs.
  • Many women do not have regular periods, and are unable to predict fertile days accurately when the likelihood of pregnancy is highest.
  • Fertility awareness takes time, effort, and comfort each day to track days of the menstrual cycle, chart body temperature, and/or monitor cervical mucus.
  • Viral infections that cause low-grade fevers can affect basal body temperature.
  • Some medications such as antibiotics or antihistamines may change cervical mucus.
  • Vaginal infections may alter vaginal discharge.
  • Learning these methods takes time and practice.
  • Using these methods consistently and correctly takes commitment, calculation, and planning.
  • Individualized instruction on the chosen fertility awareness-based method is recommended.


  • Arévalo, M., Jennings, V., & Sinai, I. (2002). Efficacy of a new method of family planning: The Standard Days Method. Contraception, 65(5), 333–338.
  • Arévalo, M., Jennings, V., Nikula, M., & Sinai, I. (2004). Efficacy of the new TwoDay Method of family planning. Fertility and Sterility, 82(4), 885–892.
  • Hatcher, R.A., Trussell, J., Nelson, A. L., Cates, W., Kowal, D., & Policar, M.S. (2011). Contraceptive Technology, 20th revised edition. Contraceptive Technology Communications Inc.
  • Fehring, R.J., Schneider, M., Raviele, K., Rodriguez, D., & Pruszynski, J. (2013). Randomized comparison of two internet-supported fertility-awareness-based methods of family planning. Contraception, 88(1), 24–30.
  • Frank-Herrmann, P., Heil, J., Gnoth, C., Toledo, E., Baur, S., Pyper, C., et al. (2007). The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple's sexual behavior during the fertile time: a prospective longitudinal study. Human Reproduction, 22(5), 1310–1319.
  • Jennings, V., Sinai, I., Sacieta, L., & Lundgren, R. (2011). TwoDay Method: A quick start approach. Contraception, 84(2), 144-149.
  • Sinai, I., Jennings, V., & Arévalo, M. (2004). The importance of screening and monitoring: The Standard Days Method and cycle regularity. Contraception, 69(3), 201–206.
  • Standard Days Method
  • TwoDay Method
  • U.S. Selected Practice recommendations (US SPR) for Contraceptive Use 2016

For additional information on natural family planning and fertility awareness-based methods:

Content created by Office of Population Affairs
Content last reviewed on May 31, 2019