Although some people (mostly conservative Romanists) would like you to think that the Roman Catholic Church has only one view on contraceptives, the issue is actually one on which there is a degree of disagreement, as illustrated in the following two articles:
On the "pro" side, Manuel Clemente, Bishop of Porto (link to article).
"Speaking to journalists, the Roman Catholic Bishop of Porto Manuel Clemente said condoms in such cases are 'not only recommendable, they can be ethically obligatory.'"
On the "con" side, Matthew Bellisario, editor of the "Catholic Champion" web site (link to article)
"Well how does this genius think that AIDS is spread? Does MR Juppe know that it spreads by having sex, and that condoms promote sexual intercourse among people in Africa that have AIDS? Condoms are not 100% effective and the disease is primarily spread by sexual intercourse. Wow, I just wonder how someone like this clown becomes a Prime Minister in any country outside of Wonderland."
Obviously, Mr. Bellisario is not making his comment directly to Bishop Clemente, and perhaps he'd be embarrassed to call one of the bishops of his church a "clown" - though he does not hesitate to law on the compliments when it comes to the former prime minister. But leaving aside the bombastic nature of Bellisario's remarks, what we see from this comparison of views is that the typical Romanist apologetic argument that we need Rome to give us unity on issues like contraception (which are not explicitly addressed in Scripture) is wrong as a matter of fact: although Rome provides organizational unity, that organizational unity masks great doctrinal and moral disunity.