Thanks for those links Phil, It was very helpful to see that not everybody agrees about this issue.

Regarding Natural Law: Why is it that the church believes we should adhere to Natural law when it comes to spiritual issues. After all, Survival of the fittest and survival at all cost can be a very Natural, but also very unloving approach to life. Surely we as spiritual beings can go against nature in the interest of God, Love and Relationship.

For example, if having more children would negatively effect my relationship with my wife and my two boys and decrease our standard of living due to the cost of another child, then it seems the spiritual and good choice to simply cut reproduction out of the equation when it comes to my sexual relationship with my wife. This choice is made not to go against nature in an evil or sinful way but rather to make a spiritual choice through my understanding of the natural world.

In a sense Jesus' healing of people went against nature through a spiritual choice to heal a natural problem - though I suppose one would argue that disease is not natural in a perfect world, but we don't really know that do we.

Jacques, natural law isn't so much about how nature behaves as about what we can determine about right and wrong using our human reason (as opposed to relying on Revelation). In Humane Vitae, the Catholic Magisterium made the controversial statement to the effect that it has the truest read on natural law. This didn't go over very well in Protestant circles, nor with rational people of good-will outside the Church.

The family situation you describe is a common one, and the current teaching does allow for the spacing of children or even to decide to have no more, for economic or other reasons. The only lawful methods allowed to do so, however, are "natural" -- NFP, rhythm, abstinence, etc. This is, of course, where the controversy lies, as many theologians have maintained that non-abortive artificial methods (condom, diaphragm, some forms of the pill) ought to also be allowed as well. Jim Arraj's book does a nice job pointing out that the procreative dimension of family life is more than biological, but must consider the spiritual atmosphere of the family, which is the "environmental womb," as it were, in which the child is raised. What is good for this family atmosphere is as much a procreative concern as whether one's sexual plumbing is open or obstructed by some artificial means.

Read, reflect, dialogue, talk it over with a priest or two, and make your decision about this. Then be at peace that you have formed your conscience and are acting accordingly.