I can see it as a fantasy, but first and foremost, I am not a homewrecker and I would never compromise my morals for such a conquest. It would have to be one of those weird situations where her man was into it, if ever. Or it would have to be a situation where I had a relationship with a girl that was pregnant just prior to us meeting.
A few years back, I stopped in at a restaurant I had worked at months earlier and ran into this girl I'd always really thought fondly of. Kind of a dumb blonde (no offense, but she really did fit the stereotype), but cute and just sweet as pie. Would have really made an awesome girlfriend with her personality. Anyway, she was pregnant and came out when I was eating and things were slow to tell me about how her boyfriend had dumped her after the pregnancy and things were going tough for her. I don't know what it was, but aside from truly feeling for her and being sympathetic to her situation, I wanted to put her on the table and fuck her like there was no tomorrow. She gave me her phone number and told me to call her and we'd hangout sometime. I never did. I don't know why. I feel stupid. I still carry her number in my wallet and think about her sometimes. That was about 4 or 5 years ago.