Natural Family Planning

NFP is something that Catholic couples can only lawfully use under certain circumstances. It is an exception morally, and it is never to be the rule. I can think of three cases where it could be used morally: danger of health for one of the spouses (more likely that of the woman I would imagine), extreme poverty (when it would be impossible to adequately raise children or have more children), and imprisonment (like in a Communist prison for a long period of time).

Agreed but even that should be sparingly used. Fr. Scott wrote something about it and I completely agree with him. Here are some of his words.

Fr. Scott wrote:

....Artificial birth control, which is the destruction of Catholic families, is no longer condemned as a mortal sin, for marriage is now considered in a selfish way, as being for the couple itself, rather than an outpouring of love desiring to participate in God’s work of creation and sanctification of His children. The so-called practice of Natural Family Planning (NFP), propagated in the post-Conciliar Church as a "Catholic" method of contraception, derives also from the same contraceptive mentality. Since marriage is considered primarily for the couple itself, they consider themselves free to determine the number of children and their spacing. This can be a mortal sin if NFP is employed without sufficient reason, as approved by the Church (e.g., serious eugenic, social, or medical reasons, such as danger to the life of the mother through additional children). Whether it be through artificial or natural means that the first purpose of marriage is frustrated, such couples who are not willing to accept all the children God sends them do indeed fail to live up to their marriage vows.

I guess it'd be better if we used the term "birth spacing" instead. Mothers should be given some time to recuperate before conceiving yet another child as we all know pregnancy/childbirth entails a lot of pain.

Marriage is for the bringing of children (God fearing ones) into the world. Pleasure should only come as the next primary concern.

Yes, the primary end of marriage is put under the secondary end these days. Emphasis is put too much on the couple. In fact, the ends are reversed. Children are sadly not wanted much in this world. Hence, cooperation with God's creative power is also not wanted in that case then.