Natural Family Planning (NFP) is a scientific method for determining human fertility through the observation of a woman's biological cycles. It is a natural alternative to artificial birth control, and, in his 1968 encyclical Humanae Vitae, Pope Paul VI endorsed such methods as the only moral means of regulating family size.
But NFP is practiced by many non-Catholics as well, because it avoids chemical birth control that may cause abortions; it is inexpensive; it encourages couples to share responsibility for family planning; it is helpful for both delaying and achieving pregnancy; and it works!
The Effectiveness of NFP
A research study conducted in Germany and released in 2007 concluded that the sympto-thermal method (STM) of NFP, when used correctly, resulted in "0.4 pregnancies per 100 women per year"—an effectiveness rate of 99.6 percent. Lead researcher Dr. Petra Frank-Herrmann told BBC News that "the effectiveness of STM is comparable to the effectiveness of modern contraceptive methods such as oral contraceptives, and is an effective and acceptable method of family planning."
Learning About NFP
Unlike the Pill, NFP is not a "set it and forget it" method of regulating birth. It takes some effort, and it is very important to learn any NFP method from an instructor--either in person or through a correspondence course. Books can only supplement individual instruction. The websites listed in the sections below offer information about their particular methods. Your local Catholic church can also provide the names of NFP teachers in your area.
With proper NFP training, however, a couple can reliably space births without the use of morally unacceptable forms of birth control.
NFP is an umbrella term describing many different methods of scientifically determining a woman's fertility. Each method relies on a variety of physical indicators to track the progress of a woman's monthly cycle. The most common methods include sympto-thermal methods; mucus-only methods; and and a relative newcomer, the Marquette Model, which measures hormone levels in addition to other factors. Brief descriptions of each of these can be found below, and more information can be found in Natural Family Planning Resources.
Sympto-thermal methods track waking temperature and observations of changes in cervical mucus to determine the fertile and infertile times in a woman's menstrual cycle. Two of the most prominent organizations that teach sympto-thermal methods are the Couple to Couple League and Northwest Family Services. Both offer in-person instruction and correspondence courses.
Mucus-only methods track changes in cervical mucus and/or sensation. Observations are made, recorded, and interpreted depending on the method. In the Billings Ovulation Method and the Family of the Americas Ovulation Method, women observe sensation at the vulva as they go about daily activities and notice any mucus that is visible when using the bathroom. In the Creighton Model, woman observe the sensation produced by mucus as they wipe with toilet tissue before and after urinating and observe the appearance of any cervical mucus. There is a standardized vocabulary of mucus descriptions to describe what they see.
The Marquette Method
The Marquette Method combines cervical mucus observations with ovulation predictor tests using the ClearBlue Easy Fertility Monitor. The monitor measures hormone levels to help indicate when ovulation occurs. By combining information from the fertility monitor with mucus observations, couples can determine when the woman is fertile.
Learning More About NFP
You can learn more about the various methods of NFP and the organizations that other training in each method in my listing of Natural Family Planning Resources. In addition, most Catholic dioceses offer some kind of NFP training, and many of them now require NFP training as part of the standard preparation for receiving the Sacrament of Marriage. Because the Catholic Church teaches that NFP is the only morally acceptable method of regulating birth, diocesan training programs will happily accept non-Catholics as well.