NFP: A Defense and an Explanation

What are the conditions according to which one may use NFP without offending Almighty God?

When is it licit for a married couple to use natural family planning (NFP)? What are the conditions according to which we may use this method without offending Almighty God? This will be my subject in this article both with reference to what the Church’s Magisterium has said and with some theological reflections on its place in married life. For without doubt in some circles NFP has acquired a dubious reputation, a reputation which I consider largely undeserved and which I hope this article can do something to improve.1

Very often it is said that natural family planning is restricted to hard cases, that for its legitimate use a serious reason is required. But such a judgment is based upon no magisterial text that I am aware of; in fact, the chief texts do not say this at all.2 Let us look at these texts, but before doing so it would be well to consider the place of children with regard to sexuality and marriage.

Just as the human race would have no capacity or need for eating unless we needed eating to nourish our bodies, so we would have no capacity for sexual activity if that activity were not oriented toward the procreation of children. Although both eating and sexuality have other goods connected with them, such as legitimate pleasure, fellowship, strengthening of the bonds between spouses, the allaying of concupiscence, nevertheless neither would exist unless it had the obvious function that it has, providing either for the good of the individual or of the human race. In fact, the obvious connection of sexuality with procreation is one of the best means of demonstrating to modern pagans and secularists that a hedonistic ethic is contrary to human nature itself. Sex is not simply there; it has a built-in purpose.

Now marriage is the context within which both nature and the revealed law of God command that sexual activity take place. Since sexual activity left to itself usually results, sooner or later, in children, these children clearly need parents to protect and raise them. Marriage and the family exist chiefly to provide the proper context for child raising. Thus the Church formulated the entirely commonsense teaching that the principal end of marriage was children, both their procreation and their education. “Finis principalis Matrimonii est generatio et educatio prolis,”3 or, “the principal end of marriage is the procreation and education of children.” This is not to devalue the other ends of either marriage or sex,4 but simply to point out the obvious fact that we have the capacity and desire for sex because it is our means for passing on the gift of life. Otherwise we would not even have such a capacity and desire.

Anyone then who deliberately engages in sexual activity while, at the same time, blocking in some way the natural consequences of such acts obviously acts against nature, against the very nature of man. It is not good to extol the naturalness and beauty of sex and at the same time render the sex act unnatural by a use of perverse human technology.

In natural family planning, of course, one does not seek to render the sex act artificially sterile or block its natural consequences. Whatever consequences God and our created human nature have placed in the act are retained. To be sure, the intention is to restrict such activity to times when the wife is likely to be infertile. But is there anything wrong with this, and, if not, what conditions, if any, must be fulfilled for its licit use?

I should point out first of all, that our intention does not constitute the only criterion of morality. Act, motive, and circumstances: these are the three traditional criteria for judging moral acts. If I need fifty dollars for some legitimate purpose, it makes a big difference whether I get a job and earn that money or whether I steal it from someone. The motive may be the same in each case, but the means differ and render the one act morally good and the other evil. The same is true with regard to sexual morality.

Although since the middle of the nineteenth century several decisions of the Sacred Penitentiary had made it clear that NFP use was not illicit, the first papal statement on it was in Pius XI’s magnificent encyclical, Casti Connubii (1930). After a condemnation of anything that may interfere with the conjugal act to prevent conception, the Pontiff went on to say,

Nor are those considered as acting against nature who in the married state use their right in the proper manner, although on account of natural reasons either of time or of certain defects, new life cannot be brought forth. For in matrimony as well as in the use of matrimonial rights, there are also secondary ends, such as mutual aid, the cultivating of mutual love, and the quieting of concupiscence which husband and wife are not forbidden to consider so long as they are subordinated to the primary end and so long as the intrinsic nature of the act is preserved.5

The medical knowledge for the use of NFP was just beginning to be known at the time Pius XI wrote this encyclical, but within a few years that knowledge had become better understood and had begun to be distilled into popular works and set out as systems for use by married couples, known at the time, of course, as rhythm or calendar rhythm. As a result of this increasing knowledge, Pius XI’s successor, Pius XII, specified more clearly what was licit or illicit in the use of NFP. Let us look at two of his addresses on the subject.

The first of these is his famous “Allocution to Midwives” of October 29, 1951.6 Curiously this document is sometimes cited by those who seem to want to restrict unduly the licit use of NFP. But in fact, in this address Pius XII hardly even deals with the ordinary use of natural family planning. Rather he speaks primarily of those who would “embrace the matrimonial state” and “use continually the faculty proper to such a state” but at the same time avoid children entirely. And for this he rightly requires a serious reason. Why is this?

The Pontiff points out the commonsense truth that the human race depends on married couples for much of its temporal welfare. “The individual and society, the people and the State, the Church itself, depend for their existence, in the order established by God, on fruitful marriages.” Thus to embrace a state established by God for the procreation and formation of children, and without a sufficient reason to forgo altogether having children, is obviously an injustice.

It is the kind of action that causes children to cry out, “It’s not fair!” Such couples enjoy all the benefits and pleasures of marriage and deliberately reject the whole purpose for which such benefits and pleasures were instituted. But even so, Pope Pius does not forbid couples that have some important reason for entirely avoiding pregnancy to marry. For he states: “Serious motives, such as those which not rarely arise from medical, eugenic, economic and social so-called ‘indications,’ may exempt husband and wife from the obligatory, positive debt [i.e., debt to society by having children] for a long period or even for the entire period of matrimonial life.”7

The “Allocution to Midwives” sets forth the basic principles that are needed to address moral questions arising from the use of natural family planning, but it does not work these out in detail. Based on Pius’s teaching we can see that the essential moral question of the use of NFP is a question of balance, the balance of its use, and the frequency of its use, against the seriousness of the reason for that use. To make use of NFP throughout an entire marriage indeed requires serious justifying reason or to use it “for a long period” likewise. But what of other circumstances?

About a month after his earlier address, on November 26, 1951, Pius XII spoke to the Association of Large Families. After praising the generosity of husbands and wives “who, for the love of God and trusting in Him, courageously raise a numerous family” the Pontiff says the following,

The Church, on the other hand, can understand, with sympathy and comprehension, the real difficulties of matrimonial life in these our days. For this reason, in Our last address on conjugal morality, We affirmed the legitimacy and at the same time the limits—truly very wide—of that controlling of births which, unlike the so-called “birth control,” is compatible with God’s law. It can be hoped . . . that for such a lawful method a sufficiently certain [scientific] basis can be found, and recent research seems to confirm this hope.8

This second address by Pius XII, though not treating of the specifics of the moral use of NFP, certainly indicates—“limits—truly very wide”—that that Pontiff had a favorable attitude toward the use of natural family planning and did not desire to restrict it to the most narrow of circumstances. Such an attitude continued throughout his reign until the Church entered the turbulent period of the Council and its aftermath.

As everyone knows, after the Second Vatican Council it was widely expected that, despite the authoritative teachings of Pius XI and Pius XII, somehow the Church would and could change her teachings on contraception.9 But Pope Paul VI, in an action that was little short of heroic, issued his encyclical Humanae Vitae on July 25, 1968. Although, as we will see, Humanae Vitae continues the same approach to natural family planning use as found in the teaching of Pius XII, we are met with an initial difficulty, based however on an error. In the pamphlet edition of Humanae Vitae published by the Daughters of St. Paul, which features the “NC News Service Translation,” the section that deals with the licit use of NFP, section 16 of the encyclical, reads (in part) as follows:

If, then, there are serious motives to space out births, which derive from the physical or psychological conditions of husband and wife, or from external conditions, the Church teaches that it is then licit to take into account the natural rhythms immanent in the generative functions….”

This text would seem to teach that any licit use of natural family planning is confined to situations in which “serious motives” are present, so that the same conditions apply to use of NFP simply to space out births as to its use “for a long period or even for the entire period of matrimonial life,” as Pius XII had earlier taught. But this is not the case. For in this instance it is simply a case of a faulty translation. The Latin of the beginning of the above quotation runs, “Si igitur iustae adsint causae generationes subsequentes intervallandi, quae a coniugum corporis vel animi condicionibus…” (my emphasis). The word erroneously translated as serious is the Latin world iustae. Paul VI thus speaks of just causes or just reasons, and there is no mention of serious at all. Fortunately more accurate translations followed, so that in the volume of post-Vatican II documents edited by Austin Flannery, iustae is translated as “reasonable.”10 But for reasons unknown to me, “serious motives” has acquired a life of its own and one sees it repeated again and again. Paul VI did not specify exactly what he meant by “just reasons,” and we will look at that more closely below. But here we should simply note that any use of Humanae Vitae to try to show that serious reasons are required for the licit use of NFP is simply based on an error.

Let us look at just two more documents of the Magisterium in our survey of Church teaching, and first the apostolic exhortation Familiaris Consortio of John Paul II (November 22, 1981). In this document John Paul not only reaffirms the licitness of “recourse to periods of infertility” but he praises this practice as likely to lead to “dialogue, reciprocal respect, shared responsibility and self-control.” He continues, “In this context the couple comes to experience how conjugal communion is enriched with those values of tenderness and affection which constitute the inner soul of human sexuality, in its physical dimension also.”11 As he frequently did, John Paul in this passage attempts to discover the inner meaning and value of things and not simply to teach about their proper use and morality, essential though these are. And thus he discerned value in the use of NFP, value more than simply for the spacing of pregnancies.

Finally, let us look at the Catechism of the Catholic Church. In no. 2368 we find again the word “just” used by Paul VI in Humanae Vitae, and we read, “For just reasons, spouses may wish to space the births of their children.”12 This sums up what we have seen above in the teaching of Pius XI, Pius XII, Paul VI and John Paul II and may be taken as indicating the Church’s judgment on this matter.

From these documents of the Magisterium we can see that the Church does not look on natural family planning with a jaundiced eye. To be sure excusing reasons are necessary for its use. But Pius XII mentions the “very wide” limits for its licit use, John Paul II speaks of its value in the development of marital love. We have also seen that except for its use over the entire lifetime of a marriage or for “a long period” the Magisterium has never required serious or grave reasons for its use. Let us look at the issue more generally and examine the question of what might be just reasons for its use. We should keep in mind what seems to be the basic line of papal thought, namely, that the longer the use, generally speaking, the more serious the reason that will be required. Thus for example, it would seem that for a couple with only one or two children to voluntarily cease having children would indeed require some serious and extraordinary cause. Or to space children six years apart would require a more serious reason than three years. And so on.

I wish to approach the remainder of this discussion from two points of view. The first involves the question of the primary end of marriage which I mentioned above, namely, “the procreation and education of children.” Now the important thing to note about this is that the primary end of marriage is the procreation and education of children. If we forget the words “and education” we are apt to see the value of marriage only in how many children a couple can have, and even to reduce a wife’s value to that of how many children she bears. But if we consider the phrase as a whole, “procreation and education” we will reach a different conclusion. For as Pius XII noted, “The work of education exceeds by far, in its importance and its consequences, that of generation.”13 And surely here education means much more than schooling. Perhaps it could be rendered best as formation, the entire spiritual, moral, intellectual, social and physical shaping of a child, so that he can serve God in this world and attain eternal life in the next. Certainly in order to be educated a child must first be generated and born. But, as we see all too evidently around us, not all children who are procreated are educated. And if parents are indeed the first and primary educators of their children,14 then the state of the parents’ health, both physical and psychological, has a great impact on their ability to educate their children. Thus if parents are stressed or constantly tired or overworked, they are not apt to be the best educators of their children. I am not speaking of their ability to ferry their children around for the latest in art or music lessons or sports camps. Rather, I am thinking of the daily interaction of parents and children and the strength needed by parents for the sometimes arduous task of rearing their children. It does not conduce to forming children psychologically if their parents are frequently irritable or overly critical. Yet, as is obvious, fatigue and stress tend to bring out such negative qualities in human beings.

While it is true that the lesson of generous sacrifice is one of the best that parents can give their children, not everyone is capable of heroic virtue. Everyone knows mothers who bear eight, ten or twelve children and who manage such large households with little difficulty. But not everyone has the requisite emotional and physical resources to do this, so that what for some might be done without difficulty, for others might require a heroic virtue that the Church has generally not insisted on.15

Some have questioned why, suddenly in this age, Catholic married couples need to make use of NFP when for centuries such knowledge did not even exist.16 Fr. Ripperger, for example, in the article cited in note 6, states, “For centuries people have been getting married and leading perfectly Catholic married lives without knowledge of NFP” (p. 49). This of course is true. But the answer to that is found in the words of Pius XII to the Association of Large Families quoted above: “The Church, on the other hand, can understand, with sympathy and comprehension, the real difficulties of matrimonial life in these our days” (emphasis mine). With the absence of extended families, with denatured food,17 with often stressful commutes and even the evil (sometimes necessary) of both parents working outside the home, married life has difficulties that were largely unknown in earlier times. It seems as if God provided for the knowledge of female fertility at exactly the right time in the history of mankind, at the time when the increasing complexities of modern life would make such knowledge helpful and even in a sense necessary for modern families. Thus I would argue that the just causes stipulated by Paul VI for the licit use of NFP would include such reasons as stress, both physical and emotional, and considerations of general bodily health, housing conditions and income. For we must remember that the “limits—truly very wide” about which Pius XII spoke were based on his earlier assessment that it is “medical, eugenic, economic and social” causes which render NFP use legitimate.

Another line of argument I want to pursue involves a discussion of the purpose of procreation in conjunction with God’s original command to Adam and Eve, “Increase and multiply” (Genesis 1:28). One of the chief insights of the Aristotelian/Thomistic philosophic tradition is that every action has an end. Things exist for a purpose. God’s command to Adam and Eve was to bring about the peopling of the earth. While certainly the birth of every human being is a good, the duty of married couples to have children is rationally related to the population needs of the world and the Church. As Pius XII taught, “The individual and society, the people and the State, the Church itself, depend for their existence, in the order established by God, on fruitful marriages.”

A very interesting discussion of this question took place in the 1950s and early 1960s by moral theologians entirely orthodox and loyal to the Church’s Magisterium. In particular, let us look at a work written by Jesuit Fathers John C. Ford and Gerald Kelly, volume 2, Marriage Questions, of their Contemporary Moral Theology, published in 1964.18 Frs. Ford and Kelly opine that, even with absolutely no excusing cause based on health, economics, etc., no married couple is bound by the law of God to have more children than is necessary for the general conservation and gradual increase of the human race. They state, “There may be difficulty in determining the exact limit for various countries; but certainly today in the United States a family of four children would be sufficient to satisfy the duty.”19 Such an approach to the question of use of natural family planning was not limited to these two authors. As they state, “Verbal acceptance of the theory was expressed by a great majority of some thirty moral theologians who discussed it at Notre Dame in June, 1952, on the occasion of the annual meeting of the Catholic Theological Society of America.”20 I am not insisting on four children as necessarily the correct number. In Europe at least, with its falling population and huge influx of Moslems, a higher number would seem to be called for. I only wish to argue that the general approach of these authors and of the pre-conciliar moralists was correct. Agreement on the exact number of children which fulfills one’s duty is less important than acceptance of the principle involved.

In no way do I intend to disparage large families or those heroic spouses who do not wish to use periodic abstinence to space their children. My only purpose in writing is to show that the Church, always a loving Mother, speaking through her Sovereign Pontiffs, has indicated a generous attitude toward NFP use, an attitude, as Pius XII stated it, of “sympathy and comprehension” for the struggles of married couples. These couples should not have burdens put upon them greater than God requires, and to know what the requirements of God’s law are we simply turn to his Church, the Catholic Church, the ark of salvation for all of mankind.21

  1. One section of this article incorporates some material from my earlier article “Marriage and the Use of Natural Family Planning,” The University Concourse, vol. 8, no. 1, September 2002. 
  2. Humanae Vitae, no. 10, does indeed speak of “seriis causis” with reference to married couples spacing or limiting their children. However, serius in Latin means serious in the sense of “opp. to sportive, jocular” (Lewis & Short, p. 1679). It does not mean the same as gravis. As we will see, elsewhere Humanae Vitae uses iustae with reference to justifying reasons for limiting or spacing offspring. 
  3. A. Tanquerey, Brevior Synopsis Theologiae Dogmaticae, 6th ed. (Paris : Societas Sti. Joannis, c. 1923) p. 730. It would probably be possible to find literally hundreds of places – encyclicals and papal addresses, the 1917 Code of Canon Law, statements of Roman congregations, theology textbooks, catechisms, rotal decisions – where this teaching was repeated. See the compilation Papal Teachings: Matrimony, selected and arranged by the Benedictine Monks of Solesmes, (Boston : St. Paul, c. 1963). The index gives numerous references on p. 583. 
  4. This is doubtless the meaning of the famous passage in Gaudium et Spes, no. 50, which some have argued changed the Church’s teaching on the hierarchy of the ends of marriage. The Council’s teaching surely meant only that the secondary ends of marriage are not disvalued by pointing out the obvious priority of the primary end. We do not depreciate the role that a shared meal plays in creating good fellowship by noting that the primary purpose of eating is nourishment of the body. 
  5. Section 59 in Paulist translation. The Latin original is as follows: “Neque contra naturae ordinem agere ii dicendi sunt coniuges, qui iure suo recta et naturali ratione utuntur, etsi ob naturales sive temporis sive quorundam defectuum causas nova inde vita oriri non possit. Habentur enim tam in ipso matrimonio, quam in coniugalis iuris usu etiam secundarii fines, ut sunt mutuum adiutorium mutuusque fovendus amor et concupiscentiae sedatio, quos intendere coniuges minime vetantur, dummodo salva semper sit intrinseca illius actus natura ideoque eius ad primarium finem debita ordinatio.” Emphasis in original. (Acta Apostolicae Sedis 22 (1930) 539.

    A better translation of the last clause of the last sentence would run: “so long as the intrinsic nature of that act always be saved and therefore its due ordination to the primary end.” One could perhaps argue from this that Pius XI thought that so long as the nature of the conjugal act was preserved its correct orientation to the primary end of marriage was ipso facto preserved. 

  6. Reprinted in Papal Teachings: Matrimony, pp. 405-434. The sections quoted are on pages 418-19. The document is also available several places on the Internet. Original source: Acta Apostolicae Sedis, 43 (1951) 846. 
  7. Here Pope Pius differs from a recent writer, Fr. Chad Ripperger, who opines that couples “should not marry if they cannot assume the essential obligations of marriage, part of which is the preparedness to have children.” “Immodesty Unrecognized: the Problems with Teaching NFP,” Homiletic & Pastoral Review, vol. 106, no. 1 October 2005, p. 46. But where a sufficiently grave cause obtains, Pius recognizes that the secondary ends of marriage are nonetheless still present and may justify such a union. 
  8. Papal Teachings: Matrimony, pp. 434-442. The sections quoted are on pages 440-41. Original source: Acta Apostolicae Sedis, 43 (1951) 855. 
  9. Because of erroneous interpretations of the conciliar decree on religious liberty, Dignitatis Humanae, many had come to believe that Catholic doctrine could be modified to suit the changing ideas of society. See my “Catholics and Religious Liberty: What Can We Believe?” Homiletic & Pastoral Review, vol. 97, no. 4, January 1997. 
  10. Vatican Council II : More Postconciliar Documents (Boston : Daughters of St. Paul, c. 1982), p. 405. 
  11. Familiaris Consortio, 32. In Daughters of St. Paul edition, p. 52. 
  12. “Coniuges, iustis de causis, possunt suorum filiorum procreationes intervallis separare velle.” See also numbers 2369 and 2370. 
  13. Allocution to the Members of the Second World Congress of Fertility and Sterility, May 19, 1956. In Papal Teachings: Matrimony, p. 483. 
  14. Cf. Gravissimum Educationis, no. 3; John Paul II, Familiaris Consortio, nos. 36-38. 
  15. Moreover, natural family planning is perhaps not so easy to misuse as some seem to think. Unlike contraceptive use, where, especially with the pill, couples can go on unthinkingly contracepting for years on end, with NFP each month a couple must rethink their decision to postpone or avoid the possibility of a pregnancy. And, thanks to the God-given attraction of the sexes for each other, they have a strong incentive to throw caution to the winds. 
  16. Of course, a form of NFP did exist in prior ages, that of spacing births by nursing, a method still recommended and taught today. 
  17. See, for example, Fr. Denis Fahey, The Church and Farming (Hawthorne, Ca. : Omni, 1988) pp. 115-135. He begins his chapter on modern processed food with a quotation from Dr. Alexis Carrel, “Modern Man is delicate.” 
  18. (Westminster, Md. : Newman, 1964) Lest anyone think that Frs. Ford and Kelly were part of the phalanax of dissenting moralists which at that period was just beginning to operate in the open, the authors explicitly state that the Church can never approve of contraception. “The Church is so completely committed to the doctrine that contraception is intrinsically and gravely immoral that no substantial change in this teaching is possible. It is irrevocable.” p. 277 (Emphasis in original) In this period, between approximately 1963 and the appearance of Humanae Vitae in 1968, few would have been so bold as to make such a statement. Fr. Ford went on to publish an important article (co-authored with Germain Grisez) in the June 1978 issue of Theological Studies, “Contraception and the Infallibility of the Ordinary Magisterium,” arguing for the infallibility of the teaching contained in Humanae Vitae
  19. Ibid., p. 423. 
  20. Ibid., p. 422. 
  21. I have said nothing in this article about the teaching of natural family planning and about certain abuses which, it is sometimes said, may arise in this connection. These may well be true and where they exist obviously should be corrected. But they should be corrected in the light of the fundamental theological and moral principles which we have seen in the teaching of the Church, and with the aim of making knowledge of NFP available to all who can use it legitimately. 
Thomas Storck About Thomas Storck

Mr. Thomas Storck is the author of The Catholic Milieu (1987), Foundations of a Catholic Political Order (1998), Christendom and the West (2000) and numerous articles and reviews on Catholic culture and social teaching. He is a member of the editorial board of The Chesterton Review and holds an MA from St. John's College, Santa Fe, New Mexico. Many of his writings can be found online at