The ambiguous or confusing physical appearance of a woman with a big belly that makes it difficult to tell if the woman is pregnant or just plain fat.
This question is not easily resolved due to the insult to a pregnant woman if it is implied that they look fat, and the insult to a fat woman if it is implied that they look pregnant. Thus, asking the ampreguous woman any leading question would be committing a faux pas. Furthermore, asking someone in the know could eventually get back to the ampreguous woman and offend her, so the question usually just goes unanswered.
Hey, didn't Bill come to the party with that ampreguous girl? I never thought he would get some girl knocked up, but I'm pretty sure he has a phobia for fat chicks.
An AmPro is when you're in a relationship with someone and you refuse to introduce them to your friends and family; mostly because you view the person as temporary, replaceable, and/or you're an asshole.
Friend: "Hey have you met John's parents yet? You've been together for months"
AmPro (or person being AmPro'ed): "No, I think he's AmProing me. We don't have any picturestogether either."