NFP is not only reliable, but it is the only authentic method of family planning.
Since NFP methods are not contraception, their effectiveness works both ways—for achieving and postponing pregnancy. When couples wish to achieve a pregnancy they can time sexual intercourse to the fertile window of the menstrual cycle, thereby optimizing the possibility of becoming pregnant.When wishing to avoid pregnancy, studies show that couples who follow their NFP method's guidelines correctly, and all the time, achieve effectiveness rates of 97-99%. Others, who are unclear about their family planning intention (i.e., spacing or limiting pregnancy) or are less motivated, will not consistently follow the method's guidelines and have a lower effectiveness rate of 80-90%.
Effectiveness of Natural Family Planning in Avoiding Pregnancy
Couples who carefully follow all the rules for avoiding pregnancy all the time: 97%-99%
Couples who do not follow all the rules for avoiding pregnancy all the time: 80%-90%
*Note: these percentages represent the range of effectiveness provided by NFP studies. They are based on the number of pregnancies among 100 couples in one year of NFP method use.