There is no end to the amount of criticism the Catholic Church receives in regard to her teachings on marriage and sexuality, especially with regard to acceptable methods of birth regulation. Society has a basic rule that anything goes—whatever form of contraception seems safe and has a relatively high rate of success in preventing pregnancy is good for partners. But the Church's teaching begs the question: Are some forms of birth regulation better than others? Is there a fundamental difference in moral status between one form of regulation and another? And what of the 'contraceptive mentality;' is this a healthy framework in which to place human sexuality?
A Serious Moral Issue
According to the Catholic Church, "Fecundity is a gift, an end of marriage, for conjugal love naturally tends to be fruitful," and, as such, "it is necessary that each and every marriage act remain ordered per se to the procreation of human life" (CCC, 2366). 
The marriage act (sexual intercourse) is naturally ordered towards the creation of human life, as well as the unity of the couple giving themselves to each other. Agreeing with the teachings of the Catholic Church, science tells us that powerful chemical processes in the brain accompany sexual encounters, and serve to bring the couple closer together as well as maximize the body's ability to reproduce during and after intercourse [
]. To deny the procreative and unitive aspects of the marriage act is to go against the very nature of human sexuality.
Contraceptives1 seem to deny one or both of these aspects. A condom or diaphragm (barrier methods of contraception) not only denies the sperm from uniting with the egg, it also puts a psychological barrier between the couple by making the statement, "I'll take pleasure from you, but not your physical manifestation of love." Pills and chemical contraceptives deny the procreative aspect by destroying the male's sperm or by simply shutting off parts of a woman's reproductive system. Certain drugs (such as RU-486) can even act as abortifacients, destroying a fertilized embryo []; RU-486 and similar drugs and procedures definitively deny the procreative aspect of the marriage act.
The Church allows the use of Natural Family Planning for couples wishing to space out births, but only for serious reasons. A precondition to a couple using NFP is that they act not out of a selfish desire (i.e. the couple wants to have a lot of fun together, and a child would 'put a damper' on their fun), but "in conformity with the generosity appropriate to responsible parenthood" [CCC 2368]. Using Natural Family Planning, a couple will make observations about the woman's body, and, using those observations, predict the time during her menstrual cycle at which she is fertile (times when having intercourse would likely result in pregnancy). The couple can then choose whether or not to perform the marital act during this 7-12 day period, thus allowing them to know, to a very precise degree (99% for the sympto-thermal method []) whether the woman will become pregnant or not. The key difference between Natural Family Planning and contraceptives is the fact that there is no barrier to the unitive, procreative nature of the marital act using NFP.
"Planned" Parenthood versus "Responsible" Parenthood
At this point, however, it is still unclear how NFP can be a morally superior choice than contraceptives for a couple if they are trying to avoid pregnancy. The most important distinction, though, has to do with the couple's mentality in their decision to regulate the number of children they are having. As I stated above, the Church teaches that every marriage act should remain open to the procreation of human life. This means that whether or not the married couple is practicing NFP, whether or not the woman is fertile, and whether or not the couple wants to have a child at that time, they must always remain open to the possibility of the gift of a child through their sexual act.
This kind of parenthood is responsible parenthood, because being responsible means making choices that not only bring about the highest good, but also use righteous means to do so. Being responsible also means any couple wishing to regulate the number of children they have must have a very serious reason for doing so2!
As it is not my intention to discuss what constitutes proper and responsible reasons for choosing to space out births using Natural Family Planning or other methods in this article, I recommend you read pages 118-120 of Christopher West's The Good News About Sex & Marriage (dealing with the question, "So what would be just reasons for a married couple to use NFP to avoid pregnancy?"), if you'd like to know more.
In order to see more clearly, then, why NFP is a licit choice for a couple, whereas contraception is not (even if they are used for the same end—that is, to avoid a pregnancy), we must speak of means and ends.
Means and Ends
Christopher West outlines the argument succinctly and beautifully on page 117 of The Good News About Sex & Marriage, answering question 10 ("I was always taught that morality is evaluated by intention. Don't couples using NFP and those using contraception have the same intention?"):
"We must be careful to distinguish between present and further intentions (means and ends). [Contraception and NFP] may have the same further intention—to avoid pregnancy for just reasons. But their present intentions (the means by which they intend to achieve their common end) are very different. The NFP couple intends to abstain from fertile intercourse. The contracepting couple intends to sterilize fertile intercourse. These are different intentions altogether.
Take, for example, two students who both have the further intention of getting good grades. With that goal in mind, one intends to study hard, and the other intends to cheat on every test. The end never justifies the means."
Basically, what Christopher West is saying here is that while both NFP and contraception aim to help a couple avoid pregnancy (although NFP can also be used to help a couple achieve pregnancy), contraception always prevents intercourse from being procreative, while NFP does not. Another analogy West promotes is the idea of a wedding invitation; if you didn't want to invite a person to your wedding, then you would simply not send an invitation. It would be quite rude to send a letter telling someone he is not invited! In a similar fashion, abstaining from intercourse (not inviting the possibility for pregnancy) is quite different from impeding intercourse's purpose (putting up a barrier to pregnancy).
I am certain that many people will continue to disagree with the Church's teachings on sexuality (especially in this area), but I hope to have shed some light on the reasons the Church teaches what she does from a moral/ethical position. Obviously, there are far greater reasons why the Church teaches what she does, especially in relation to her theological understanding of God's relationship with husband and wife, but I have chosen to try to explain the Church's teachings without using theology. In my future studies, I will be researching this topic much more, and I hope to perhaps more fully organize my thoughts and the theology of Natural Family Planning in my master's thesis. For now, please see the 'Further Reading' section below for more information about Natural Family Planning.
Further Reading
- An Introduction to Natural Family Planning [Natural-Family-Planning.info]
- Natural Family Planning - Serious Motives by Fr. Richard Hogan [EWTN]
- Natural Family Planning [Wikipedia]
- The Good News About Sex and Marriage by Christopher West [Amazon.com]
- The Fecundity of Marriage [Catechism of the Catholic Church (2366-2372)]
- Catholic Family Planning [Envoy Magazine]
End Notes:
Note: I have used Wikipedia as a source for basic informational facts. I always take Wikipedia with a grain of salt, though, so typically I only use Wikipedia as a quick reference; for better documentation and information, especially in medical research, I would (and do) talk to medical doctors and research this information in medical references and journals. I recommend you do the same, for the sake of clarity!
1. By contraceptive I mean a method of preventing sperm from uniting with an egg, or any method of manipulating the reproductive system in order to prevent the possibility of pregnancy; i.e. by blocking the sperm from uniting with an egg. By abortifacient I mean a method of destroying a fertilized embryo or fetus.
2. One detriment to our society is the belief that the ideal family has one or two (or even zero) children, and that children are a burden to their parents. In order to understand the purpose of NFP, a couple must break free from this restrictive mentality, and see children as gifts that result from their sexual union.