What is NFP?

Natural Family Planning (NFP) is a general term for certain methods that are based on the observation of the naturally occurring signs and symptoms of the fertile and infertile phases of a woman's menstrual cycle. NFP methods are used to both achieve as well as avoid pregnancy.

Although the first methods of NFP were developed in the mid-twentieth century,2 natural approaches to determining the time of a woman’s periodic fertility are actually a very old practice. The ancient Greeks, for example, had their own theory of a woman’s ovulation that was based on their knowledge of fertility in animals. With the discovery of the woman’s time of ovulation in the early nineteenth century, scientists created a formula for a Safe Time that could help married couples plan their families. Fast forward to the 1930s when the Rhythm or Calendar Method was developed based on the research of two different scientists in two separate parts of the world who had studied hundreds of menstrual cycles. All of these natural methods did not account for the changing signs of fertility in a woman's menstrual cycle.

Today, the methods of NFP take account of a woman’s changing signs of fertility. Based on observable signs and symptoms of the fertile and infertile phases of the woman’s menstrual cycle, NFP methods track the changes associated with ovulation and treat each menstrual cycle as unique. The accuracy of a woman’s observations about her fertility has been validated by scientific research.3

NFP represents a holistic approach to family planning. Both husband and wife are instructed to understand their combined fertility and to identify their family planning intention (whether to have a baby or not). The successful use of NFP to postpone or avoid pregnancy relies upon a couple following what they know about the method and one another. The successful use of NFP requires a couple to communicate. In the daily charting of their fertile signs, married couples quickly appreciate their shared responsibility for family planning. Husbands are encouraged to “tune into” their wives’ cycles, and both spouses are encouraged to speak openly to each other about their sexual desires and their ideas on family size.

Married couples using NFP to postpone or avoid pregnancy abstain from intercourse and genital contact when the woman is fertile and can conceive. The total days of abstinence will vary from woman to woman and even from cycle to cycle. This is an important point to remember—there will be differences in the length of abstinence. Whatever the length of the fertile phase, no barriers or chemicals are used at any time to avoid pregnancy. To achieve pregnancy, couples have intercourse during the fertile time of the cycle.

NFP is not a contraceptive, it does nothing to suppress or block conception. Instead, couples adjust their behavior according to their family planning intention (that is, whether they hope to achieve or avoid a pregnancy) using the naturally occurring signs and symptoms of a woman's menstrual cycle.

The methods of NFP represent authentic family planning because they respect the nature of sexual intercourse as God made it – to be love-giving and life-giving. NFP methods promote respect between husband and wife, openness to human life and recognize the value of children. When practiced well, NFP methods can help to enrich the bond between husband and wife. As holistic family planning that works with nature, the methods of NFP are acceptable for people of various religious and philosophical beliefs.

2. The Sympto-Thermal methods were developed in the late 1940s-early 1950s. Cervical mucus-based methods were developed in the mid-1960s-early 1970s.

3. See “Research in Natural Family Planning: A Review of Studies from 1998-2003,” Current Medical Research, 14 (Summer/Fall 2003), available at: /prolife/issues/nfp/cmrsf03.shtml. See also Petra Frank-Herrmann, et al., “The effectiveness of a fertility awareness-based method to avoid pregnancy in relation to a couple’s sexual behaviour during the fertile time: a prospective longitudinal study,” Human Reproduction 22 (2007):1310-1319. Foundational NFP studies are listed in, Richard Fehring, and Robert Kambic, Natural Family Planning Bibliography (Washington, DC, 1995), available at: /prolife/issues/nfp/bibliography.shtml).