The Catholic Church does not command couples to have as many babies as is reproductively possible. The husband and wife, as mother and father, have a right to make moral and reasonable plans in terms of the size and spacing of their children. As long as moral means are used, then it is up to the couple to decide when and how many children to have with the constant proviso that God may have other plans.
While many erroneously still call it the Rhythm Method, Natural Family Planning (NFP) is as effective as any artificial means of contraception when used properly. The only difference is that this method is extremely inexpensive, involves minimal inconvenience, and is completely moral to use. Artificial contraception is immoral for several reasons, and it can be very expensive and potentially dangerous to the woman over a long period of time.
Pope Paul VI issued his encyclical Humanae Vitae in 1968, in which he spoke of the intrinsic connection of the unitive (love) and procreative (life) faculties of marriage. He saw contraception as something which created a wall that separates the two; when that happens, the sex act is no longer a sacred sign of the covenant of marriage. Instead, it reduces the sex act between husband and wife to a purely physical—not spiritual—activity. When done within marriage as a sign of the unity of the couple and their openness to God’s will should He want to bless them with new life, then human sexual intercourse is a sacred and holy act. When done purely to satisfy sexual fantasies and desires, then it reduces the couple to mere sex objects for one another.
Another concern the Church has is that many so-called contraceptives do not prevent conception; rather, they force a premature ejection of a fertilized egg. Once the sperm and egg have united, conception has taken place, and an immortal soul has been infused by God into that new human life. DNA proves that the “zygote,” “embryo,” or “fetus” is actually a distinct and separate human person. There are only human genes present, and this human DNA is unique from the mother and father in that it constitutes another complete human being and is not merely an extension of the mother’s own tissue. Many so-called birth control pills act in reality as abortifacients, that is, they cause a very early abortion of a fertilized egg (now considered a conceived child) from the mother’s womb. Conception was not prevented, but implantation was. What is ejected is very tiny, but very human nevertheless.
Finally, recent studies have shown that long-term use of birth control pills has increased the risk of breast and uterine cancer in many women. Natural Family Planning needs no prescription, has no health risk, costs nothing, and involves both the husband and wife (so that one spouse isn’t taking it easy while the other assumes all the responsibility). It can be used to space out births, and to avoid pregnancy or to facilitate it, since it is based on using the unique and personal fertility cycle of the woman.
The three to seven day abstinence from sexual relations involved for the couple using NFP allows them to foster nonsexual but very romantic encounters to bring them spiritually and emotionally closer together while avoiding the physical intimacy of sexual intercourse.