It is always of interest to carefully distinguish the problems at hand. The purpose of contraception is to prevent pregnancy effectively; abortion's purpose is to destroy an infant already conceived.
The Church insists that couples must not radically separate sex and procreation because she maintains that conjugal relations are human acts not reducible to mere instinctive conduct. More precisely, the Church does not approve the artificial methods of contraception because these, in a general way, remove from sexuality one of its essential ends. However, at the same time, the Church encourages Christians, with the help of grace, to grow in the practice of freedom and responsibility. Sexuality, freedom, and responsibility are, then, included in an integral vision of man. Let us acknowledge it: the requirements of the Church are demanding, like the rest of the Gospel.
CBCP PASTORAL LETTER: "LOVE IS LIFE" (1990)
http://www.cbcp.net/documents/lovelife_90.html