What is natural family planning, and why does the Church allow it?

Natural family planning, or NFP, helps spouses recognize the fertile and infertile phases of a woman's cycle. If they have just reasons to postpone pregnancy, they abstain from sexual intercourse during fertile periods rather than contracepting.

How it works. Modern NFP methods track biological signs of fertility, such as cervical mucus, basal body temperature, and hormonal changes. Common methods include the Sympto-Thermal Method, the Creighton Model, and Marquette. NFP can be used either to seek pregnancy or to postpone it. It is based on observable reproductive biology, not guesswork or the old calendar rhythm method.

Why the Church allows it. Married love has both a unitive meaning and a procreative meaning. Each marital act must respect both meanings and remain open to the transmission of life (CCC 2366). When spouses practice NFP, they do nothing to make an act infertile. During fertile periods they abstain, and during infertile periods they engage in the marital act as it naturally is. Periodic continence respects the body and encourages mutual responsibility and self-mastery (CCC 2370).

The spouses' reasons matter. The Church does not teach that couples must seek the largest family physically possible. Spouses may space births for just reasons related to physical or psychological health, family circumstances, or serious economic and social conditions (CCC 2368). They should discern these reasons generously before God. Fear, selfishness, or a refusal ever to welcome children can corrupt the use of NFP, even though the method itself is moral. Children remain gifts, and spouses are called to responsible parenthood rather than complete control over fertility (Ps 127:3; CCC 2373).

How it differs from contraception. Contraception deliberately changes an act before, during, or after intercourse so that it cannot result in conception. NFP changes the couple's timing and behavior through abstinence. The distinction concerns what the spouses actually choose to do, not merely whether pregnancy occurs. An infertile marital act can still be morally good when its infertility is natural rather than deliberately imposed.

In practice. Couples should learn NFP from a trained instructor rather than relying only on an app. They should also pray together and review their reasons for postponing pregnancy. A priest can help with moral discernment, while a qualified NFP instructor or physician can help interpret fertility signs.