Et Tu Jen?- who is also a convert to Catholicism and the pro-life message- has an awesome post on this subject today. Here's a brief quote:
"The message I'd heard loud and clear was that the purpose of sex was for pleasure and bonding, that its potential for creating life was purely tangential, almost to the point of being forgotten about altogether. This mindset laid the foundation of my views on abortion. Because I saw sex as being closed to the possibility to life by default, I thought of pregnancies that weren't planned as akin to being struck by lightning while walking down the street -- something totally unpredictable, undeserved, that happened to people living normal lives.
Being pro-choice for me (and I'd imagine with many others) was actually motivated out of love and caring: I just didn't want women to have to suffer, to have to devalue themselves by dealing with unwanted pregnancies. Because it was an inherent part of my worldview that everyone except people with "hang-ups" eventually has sex and sex is, under normal circumstances, only about the relationship between the two people involved, I got lured into one of the oldest, biggest, most tempting lies in human history: to dehumanize the enemy. Babies had become the enemy because of their tendencies to pop up and ruin everything; and just as societies are tempted to dehumanize the fellow human beings who are on the other side of the lines in wartime, so had I, and we as a society, dehumanized the enemy of sex."
Go check it out the full text in person and leave her a "that a girl" comment. Even better, write your own essay on the subject. (I'd be really interested to read some cradle Catholics trace how their families raised them to "always be Pro-Life")