Effectiveness of NFP

Numerous studies including one by the U.S. Government have shown that the Sympto-Thermal Method of NFP can be used at the 99% level of effectiveness for postponing pregnancy. That’s the same effectiveness as the birth control pill and better than all other barrier methods. This method is most effective when couples are taught by competent teachers, understand the method, and are motivated to follow the rules according to their family planning intention (achieving or postponing pregnancy). Those who are strongly motivated to postpone a pregnancy and follow the method strictly are very effective in meeting their goal.  

Effectiveness rates for avoiding pregnancy after one year

Source: MayoClinic.com 

* Perfect use refers to couples who are well taught, understand the method, are clear about their intentions, and carefully follow the rules. Typical use refers to couples who occasionally do not follow all rules for postponing pregnancy; generally these rates are similar to those found among couples using barrier methods of contraception.  

“The pregnancy rate of any group of NFP user couples will depend on the proportions of risk takers and high fertility couples in the cohort. We also know from the studies of Trussell and others, that if the NFP rules are followed, if couples are perfect users, the probability of pregnancy is quite low, less than 5%. Couples who follow the rules for abstaining when signs of fertility are apparent, can use NFP with confidence that they will not become pregnant” (The Effectiveness of Natural Family Planning methods
for birth spacing: A comprehensive review, Robert T. Kambic, Department of Population and Family Health Sciences
The Johns Hopkins School of Hygiene and Public Health, October, 1999). You can read a scholarly analysis of the effectiveness rates of natural family planning methods at: http://www.jhsph.edu/popcenter/publications/pdf/WP99-07.htm

NFP is also effective at achieving pregnancy. With NFP you will become aware of the most fertile days in your overall fertile time, and you will learn how to maximize your mutual fertility. In addition, your charted cycles may reveal certain patterns that can contribute to infertility and which sometimes can be corrected simply by better nutrition. Many couples of marginal fertility are helped by NFP instruction to achieve much wanted pregnancies, and the charts of those who may need medical help can assist the knowledgeable physician.