The Church’s teaching about responsible parenthood is based on the essential anthropological and ethical foundation (of fidelity and responsibility). Unfortunately, Catholic thought is often misunderstood as if the Church supported an ideology of fertility at all costs, urging married couples to procreate indiscriminately and without thought for the future. But one need only study the pronouncements of the magisterium to know that this is not so. Truly, in begetting life the spouses fulfill one of the highest dimensions of their calling: they are God’s co-workers. Precisely for this reason they must have an extremely responsible attitude. In deciding whether or not to have a child, they must not be motivated by selfishness or carelessness, but by a prudent, conscious generosity that weights the possibilities and circumstances, and especially gives priority to the welfare of the unborn child.
-St. John Paul II, Discourse at Castel Gandolfo, July 17, 1994