Many of us, unaware of (Catholic) Church teaching, have used birth control. Either one method or another, chemical or barrier. Ultimately, many women have found birth control to be harmful or lacking sensation, or both. (for more information on how Birth Control negatively affects a woman see:
http://onemoresoul.com/contraception/risks-consequences/what-a-woman-should-know-about-birth-control.html) Women then begin to question each other, "Which method works best for my situation?" If you've been on a women only forum it won't take long for you to spot these women. Thousands of them are searching for something. None of them are ever told to try Natural Family Planning. Why? because of the utter failure of the 'rhythm method', lack of knowledge about the newer effective methods, and many other myths and misconceptions. Basically, we are raised in a world that believes, "Unprotected (meaning birth control) sex is stupidity." Afterall, who would want to end up like the Duggars?! is usually the next exclamation. While there is nothing wrong with a large family, it is not for everyone and the Church recognizes that. We are not required to have as many as possible, but to space our children responsibly.
Before this can really continue, we need to read what the Bible and the Church teaches:
The Catechism of the Catholic Church
2368 A particular aspect of this responsibility concerns the regulation of procreation. For just reasons, spouses may wish to space the births of their children. It is their duty to make certain that their desire is not motivated by selfishness but is in conformity with the generosity appropriate to responsible parenthood. Moreover, they should conform their behavior to the objective criteria of morality:
When it is a question of harmonizing married love with the responsible transmission of life, the morality of the behavior does not depend on sincere intention and evaluation of motives alone; but it must be determined by objective criteria, criteria drawn from the nature of the person and his acts, criteria that respect the total meaning of mutual self-giving and human procreation in the context of true love; this is possible only if the virtue of married chastity is practiced with sincerity of heart.156
2370 Periodic continence, that is, the methods of birth regulation based on self-observation and the use of infertile periods, is in conformity with the objective criteria of morality.158 These methods respect the bodies of the spouses, encourage tenderness between them, and favor the education of an authentic freedom. In contrast, "every action which, whether in anticipation of the conjugal act, or in its accomplishment, or in the development of its natural consequences, proposes, whether as an end or as a means, to render procreation impossible" is intrinsically evil:159
Thus the innate language that expresses the total reciprocal self-giving of husband and wife is overlaid, through contraception, by an objectively contradictory language, namely, that of not giving oneself totally to the other. This leads not only to a positive refusal to be open to life but also to a falsification of the inner truth of conjugal love, which is called upon to give itself in personal totality. . . . The difference, both anthropological and moral, between contraception and recourse to the rhythm of the cycle . . . involves in the final analysis two irreconcilable concepts of the human person and of human sexuality.160
2399 The regulation of births represents one of the aspects of responsible fatherhood and motherhood. Legitimate intentions on the part of the spouses do not justify recourse to morally unacceptable means (for example, direct sterilization or contraception).
And this is an infalliable doctrine (cannot be changed):
The Church also has affirmed that the illicitness of contraception is an infallible doctrine: "The Church has always taught the intrinsic evil of contraception, that is, of every marital act intentionally rendered unfruitful. This teaching is to be held as definitive and irreformable. Contraception is gravely opposed to marital chastity, it is contrary to the good of the transmission of life (the procreative.aspect of matrimony), and to the reciprocal self-giving of the spouses (the unitive.aspect of matrimony); it harms true love and denies the sovereign role of God in the transmission of human life" (Vademecum for Confessors 2:4, Feb. 12, 1997).
Also let's take a minute to observe the Bible and how God has worked through NFP in the past. Consider Who opens and closes a womb, mankind (contraception) or God (NFP)?
Genesis chapters 29 and 30: Jacob's wives Leah and Rachel
1 Sam. 1 Elkanah "loved Hannah" but the Lord had shut up her womb
What about the New Testament? We should not forget the case of Zacharias and Elisabeth, John the Baptizer's parents. "And they had no child, because that Elisabeth was barren, and they both were now well stricken in years...But the angel said unto him...Zacharias...thy prayer is heard; and thy wife Elisabeth shall bear the a son, and thou shalt call his name John" (Lk. 1:7, 13).
I am going to omit Onanism, because of the widespread confusion and the large cross-referrencing that has to be done to understand this chapter clearly. Isaiah 66:9 has God speaking that it is He who can close a womb.
1 Cor. 7:5 Do not deprive each other, except perhaps by mutual consent for a time, to be free for prayer, but then return to one another, so that Satan may not tempt you through your lack of self-control. What does that mean, to be free for prayer? Prayer for what? Discernment on spacing the births of your children. Doesn't it make perfect sense that you'd be praying if the time was right or not to concieve? And further, that you'd have to abstain during this time of fertility/ovulation until you were certain of God's will. I believe this is a biblical example of NFP.
So if I allow God to open and close my womb naturally (via ovulation or not ovulating), then it stands to reason that I can space my births based upon God's plan. That to me is the biggest thing. It is not my job to close the womb with contraception! This is the difference between spacing children via contraception or using natural family planning. The means, not the ends, is how it is morally decided.
Benefits and Effectiveness of NFP:
The Crieghton Model (For example) CrMS is 99.5% effective with perfect use and 96.8% effective with typical use. The WHO (World Health Organization) has performed several large-scale trials that have demonstrated an unintended pregnancy rate of between 0.3 and 3%, which is as good as any artificial form of birth control except sterilization. One very large trial involving about 20,000 Indian women showed an unintended pregnancy rate of less than 0.3%. The condom has a failure rate that is estimated to be between 10-30%. This means...you are more likely to get pregnant using condoms, then you are NFP.
When we say this is the best kept secret, that's no joke. NFP works and not just for women with 'special' bodies that have regular cycles and are some kind of 'exception' to the rule. Most women are irregular and use NFP sucessfully, including me. You are not 'taking chances'.
Benefits include (but not limited to): easy to learn, personalized for each couple, monitors a woman's health and teaches a woman more about their own body, no side effects, inexpensive (the price of paper charts and stickers, making them cheaper than condoms), can be used at any stage in a woman's life (breastfeeding), morally acceptable to God, respects fertility instead of treating it like a disease, promotes marital bonding, views children as gifts, involves the husband for support and decision making, encourages talks between spouses about fertility, the 'honey moon' effect (basically, after abstaining for a week, you feel like it's your honey moon all over again), helps prevent women from becoming solely an object of sexual gratification, no increased risk of cancer. Couples who use NFP have a divorce rate that is less than 5% far lower than the national rate of about 50%. And finally, it's green to NFP. Couples that throw away condoms or have hormones come out from the woman's urine (that we are not able to get out of the water supply despite techonology) harm our Earth, ourselves and our children (some say the fact that children consistently hit puberity sooner is caused by increased hormones in our water suppy), doesn't being able to recycle old charts and stickers sound so much more enviormentally friendly :)
Now the question becomes, not why would you use NFP, but Why would you not?!