With natural family planning/fertility awareness methods, or NFP/FAM, women track their monthly cycle's fertile and infertile phases either to seek or avoid pregnancies. With proper training and commitment, modern NFP/FAM methods can work just as well at preventing pregnancy as "artificial" contraceptives. This is true for NFP/FAM users in both the developed and developing worlds.
Like other family planning methods, each variety of NFP/FAM has one effectiveness rate for its correct, consistent use and another for its actual practice. Both rates are expressed as the percentage of women (number out of a hundred) on the method who do not get pregnant over one year. When couples using NFP/FAM experience unintended pregnancies, it is more often than not because they break method rules and have unprotected sex during the fertile phase.
Calendar-Based Methods
With calendar-based methods, women count the days of their monthly cycles to estimate the most likely times for their infertile and fertile phases. As of 2010, the standard days method has largely replaced the oldest calendar-based "rhythm method."
Many women with regular monthly cycles between 26 and 32 days can practice the standard days method. Compared to the rhythm method, it has simpler rules, is easier to follow and thus is far less prone to user error, especially if practiced with a color-coded visual aid, such as CycleBeads. The effectiveness rate for correct and consistent use is over 95 percent and for actual practice 88 percent, compared to 91 percent versus 75 percent, respectively, for calendar rhythm.
Symptoms-Based Methods
Symptoms-based methods rely on observation of bodily changes that indicate the fertile and infertile phases of a woman's cycle. Different studies have reported different success rates for some of these methods. The TwoDay and Billings Ovulation methods primarily observe patterns of mucus secretions from the cervix. The TwoDay method has a correct and consistent use effectiveness rate of 96 or 96.5 percent and typical use rate of 86.3 percent, and the Billings Ovulation method has a 97 percent versus 77.7 to 89.5 percent rate, respectively.
The basal body temperature, or BBT, method notes patterns in daily body temperature across the woman's monthly cycle. With correct, consistent use, it reportedly prevents pregnancy 99 percent of the time. There is no reported rate for typical use. The symptothermal method, which combines the BBT and Billings methods, has a correct and consistent use effectiveness rate of 98 to 99.7 percent versus anywhere from 80 percent to 99.8 percent for typical use.
Lactational Amenorrhea Method
The lactational amenorrhea method, or LAM, is based on the ability of breastfeeding to suppress ovulation, the monthly release of an egg cell from a woman's ovary. Women can prevent pregnancies with LAM if their periods have not yet returned, and if their babies are less than six months old and exclusively or almost exclusively breastfed. With correct and consistent use, LAM is over 99 percent effective versus 98 percent effective in actual use.
Method Combinations
Combining multiple methods of NFP/FAM may boost their effectiveness. Yet most data on effectiveness addresses only one method at a time. Nor is much known about the effectiveness of NFP versus FAM, two distinct philosophies of prevention that use most of the same techniques. During a woman's fertile phase, NFP allows only abstinence from all sex, where FAM accepts forms of sex other than penis-vagina and allows barrier methods like condoms.
References
- K4Health: Family Planning: A Global Handbook for Providers
- Institute for Reproductive Health, Georgetown University: What Is the Standard Days Method?
- Journal of the American Board of Family Medicine: Fertility Awareness-Based Methods: Another Option for Family Planning
- World Alliance for Breastfeeding Action: LAM Site
