Only God has absolute dominion over human life. This is the reason that contraception is intrinsically evil. We know that human life begins at conception. We exist in time because God chose us from eternity. A human decision to prevent our conception is a trespass on God's dominion over human life.
Abortion destroys a human life.
Contraception distorts the meaning of human sexuality. It is perfectly legitimate to acknowledge that there are circumstances under which a couple should not have a child. There can be medical, social, financial, psychological, or other reasons for this. To acknowledge God's dominion means to not act independently. In planning one's family one may never destroy the meaning of sexual union on one's own initiative.