a) First of all, we must not lose sight of the fact that many contraceptive products act equally against nidation, that is to say, they are abortifacient. This said, we must admit that most classic contraceptive methods have, in principle, a temporary effect, while sterilization is definitive; techniques for reversing it being, as we know, very uncertain.
b) But it is precisely the temporary and provisional character of contraception that makes for a special problem. The psychological mechanism that intervenes here is well known to those who are attentive to human behavior. Contraception separates procreation from pleasure, but not, they say, rejection of the transmission of life definitively; only as a delay. The pleasure is there, with its reproductive potential, but this potential is suspended and psychologically speaking, procreation is deferred or adjourned.
c) It is one thing for spouses to have recourse to decent means for postponing conception when special circumstances justify this decision; should the occasion arise, it is even a way for them to exercise responsible parenthood. Quite another thing, however, is to maintain a habitual attitude of deferring procreation. Such an attitude is not, in effect, without risk, for in practice everyone knows from experience that delaying an action until later can sometimes mean not acting at all. We know, for example, what goes on among university students; some delay for a time their decision to get to work studying for their exams, and they wind up doing so too late.
d) In the matter of contraception, analogous psychological mechanisms intervene. Some young couples separate pleasure from procreation, all the while asserting that they are only deferring the latter. Now, as time passes, these couples see developing in themselves a growing perplexity: "Aren't we getting too old to have children?" And as the woman approaches 35, another consideration confirms her doubt: it is explained to her that at her age she runs the risk of producing an abnormal child.
Thus the period of effective fertility is reduced for couples practicing contraception. While a woman's fertility naturally extends from around 15 to 49, the fertile period for couples having recourse to contraception shrinks to a few years and sometimes disappears totally.
Hence, it is evident that making contraception so commonplace is one of the major causes of the demographic collapse of the so-called developed countries.
CBCP PASTORAL LETTER: "LOVE IS LIFE" (1990)