The words ‘Natural Family Planning’ (or NFP) is heard quite often in Catholic circles. But what exactly is NFP? Well, it involves several aspects. First, it is a way by which a couple can monitor their combined fertility based on different physiological markers of the woman – cervical mucus, basal body temperature, hormones etc. Secondly, it enables the couple to know days of fertility and days of infertility in a month. The couple can discern their family’s size and can use cycle charting to plan, space or postpone pregnancy.

When a couple gets married, on their wedding day, a new family is born! Two people with different personalities and from different family backgrounds come together and enter this beautiful sacrament. Marriage is a special sacrament, unlike any other relationship, and is modeled after the Trinitarian love. The couple is called to imitate the selfless love of the Father, Son and Holy Spirit. The same Trinitarian love that overflowed and created life: “Let us make man in our image, after our likeness” (Genesis 1:26). The married couple, in their union, is entrusted with the great privilege of being co-creators of new life. Sacrament of marriage is a great calling to the communion of Trinity, to model Trinitarian relationship through a deep intimate union between the spouses and to live out the ‘creative’ privileges.

On their wedding day, the couple makes four promises to each other – of a “free, total, faithful and fruitful” love. ‘Free’ meaning they are entering into this commitment freely and willfully, without force, coercion or financial contract. By ‘total’, they promise to share everything (physical, emotional and financial) with each other and promise to accept everything about the other. ‘Faithful’ means by choosing this particular person they are saying ‘No” to all others and by saying ‘Yes’, they are making this commitment till death separates them. By ‘fruitful’, they are acknowledging that each of them is bringing their physical capacity to be a mother/father into their relationship, and that they will be open to the fruitfulness that results from their union. These promises that they make in front of God, family and friends are fulfilled through the physical union between the husband and wife. All physical unions from thereon will continue to be the renewal of these promises made on their wedding day – to a free, total, faithful and fruitful love.

The promise to be fruitful requires that every act of physical intimacy between the married couple meet the two-fold purpose – of union and of procreation. Thus, any active step taken intentionally to decrease, cover, stop, or interrupt fertility or implantation or interrupt the natural course of sex is contraceptive in nature. Contraceptives include withdrawal method, condom,  birth control pill, morning- after pill, birth control ring

“The exercise of responsible parenthood requires that
husband and wife, keeping a right order of priorities,
recognize their own duties toward God,themselves, their
families and human society”


(NuvaRing), contraceptive patch, intra-uterine device, contraceptive implant (Nexplanon), vasectomy, tubal ligation, spermicidal creams, gels and sponges. Using these methods during the physical act directly interferes with the openness to procreation, and involves breaking the promises made on the wedding day.

Unlike contraceptives, NFP methods involve better understanding of the couple’s combined fertility. Generally, a man’s fertility starts during puberty and continues his whole life. A woman’s fertility, on the other hand, starts around age 11 and ends around age 45 with menopause. On a monthly basis, a woman is fertile for only a handful of days. Different NFP methods take advantage of the scientific facts known about female body, hormones, cervical mucus, egg, and sperm survival to determine the particular protocols. There are different schools of NFP out there. Billings Ovulation model looks at cervical mucus. Symptothermal method combines cervical mucus readings, basal body temperature and other signs of hormonal changes. Creighton model looks at cervical mucus with great detail, and this type of charting is able to reveal different female health conditions such as low progesterone, PCOS, endometriosis, endometrial polyps and so on. Each couple will have to find the particular method that works for them.

Couples using NFP are encouraged to discern their readiness for a child on a monthly basis and depending on their decision, utilize or abstain during the days of fertility. NFP encourages both husband and wife to be active in discerning about their family size and, that too, on a regular basis. It encourages communication, support, creative ways of affection, and overall, a greater intimacy between the couple. While the time of abstinence can be difficult, with proper orientation and grace, it encourages the couple to grow in self-disciple, selflessness, service, deeper love and the virtue of chastity within marriage. The grace poured into the marriage can help the couple to persevere through difficulties and to attain holiness, the purpose to which the couple is called through this sacrament.

When discerning about family size and spacing kids, the couple is encouraged to practice responsible parenthood that takes into account the current physical, economical, psychological and social conditions of the family. In Humanae Vitae, Pope Paul VI writes, “In a word, the exercise of responsible parenthood requires that husband and wife, keeping a right order of priorities, recognize their own duties toward God, themselves, their families and human society.” When making the decision appropriate for their family, the couple is called to honor the promises made on their wedding day and to use natural ways to achieve their desired decision.

Natural Family Planning is  a beautiful, cooperative, cost- effective and virtuous way of  living out the promises made on wedding day. Catholic couples are encouraged to embrace their combined fertility as a true gift from God and live it out naturally, generously and responsibly.

Sherin Alexander, A Jesus Youth, A Physician Assistant at a family practice, a certified Marquette Model Natural Family Planning instructor lives with her husband in Chicago.