Dating advice needed, please help.?

For the past month I haven't dated anyone, having recently had a six month relationship end, it was her decision. Over the weekend I happened to notice that a woman, I'll call her Sabrina, that I was acquaintances with had a Facebook account. Sabrina and I have lots of casual friends in common since we participated in a sports league together. I am attracted to her and when we were both active in the league I would have asked her out but she was engaged. (I absolutely refuse to date anyone that is dating someone so the engagement issue definitely ended my interest.) A few months ago, while I was dating someone else, I learned that Sabrina's engagement ended and that she was no longer involved in a relationship. Yesterday Sabrina accepted my Facebook friend request and I soon discovered that she is about six months pregnant. I feel that my sentiment towards her hasn't changed since learning that she is pregnant, why should it? I am somewhat confused as to how to move toward asking her out. I suppose I should just ask her if she's dating, her FB page doesn't mention any relationship. Maybe I'd do better just asking other acquaintances for their insight. What are your thoughts on asking out a woman who is pregnant out on a date. Part of me says she's very vulnerable and I should proceed with extreme caution. Help, thanks, g.