Is the Missionary Position Oppressive?

Last week, I was talking to one of my dear friends who goes to a Catholic University and somehow we got on the topic of sex (surprise, surprise). She informed me that not only does the Catholic church only believe sex is for procreation within marriage (thereby discounting any form of non-heterosexual sex) but that the only acceptable way to have sex is in the missionary position. I was a bit taken aback and surprised that the church would care. Why is the missionary position the only "acceptable" way to have sex, according to the Catholic church? Perhaps it's the theory that it's the best position to promote pregnancy or the fact that the man is on top, controlling the pace of the thrusting. Although the missionary position can seem domineering, I don't think it in itself is the problem. Sex should be whatever works for whoever is involved, and if having sex in only the missionary position is what some people choose, who is anyone to tell them they're wrong? It is not my, nor anyone else's, place to judge a person's sexual choices. As long as the people involved are consenting, anything goes, from group sex to monogamous missionary within marriage. Is the missionary position sexist? I think it depends on the situation and the people involved. It has the potential to be problematic to some. However, I think it's much more oppressive to limit people's choices when it comes to expressing their sexuality.