No, it's not an oxymoron.
I actually live in a district with a pro-life Catholic Democrat representing us in our state legislature. I voted to re-elect her this last fall, since she puts her votes where her mouth is, in spite of the criticism of colleagues in her party.
Here's a post at The American Catholic by another Pro-Life Democrat, this time from Florida. Everyone in the movement should read his post.
Life should not be a partisan issue, people.