aaand me makes 4. I am the youngest by a long shot. Got my fetish in like middle school. Every year, one or two of my teachers got pregnant in midsummer (because they get an extra 3 months of maternity leave with summer vacation), so I'd just watch them grow all year. It was always the ones I found attractive without the belly too.
but what about it do I find attractive? hm…
I suppose I see it as a woman using her body to it's fullest extent, which is something more than half of us can't do. Guys have no use for nipples, dicks are less of a hassle to be sure, but ultimately don't do much outside of sex other than hang there and make us immune to uits. It's like a woman hitting the "yeah, I was a hot girl before, but now everything you found hot about me before is full steam ahead" switch.
I see it as a woman loving somebody so much (or sex so much, I suppose) that she's willing to become extremely inconvenienced for months on end, for the sake of satisfying her feelings/cravings.
I also just like curvy, shapely, round things. And a pregnant belly is the curviest, shapeliest, and roundest thing of all. I feel like that's hardwired into most dudes'subconsciousness, because boobs and butts. Which, I think, is why most guys that don't have a particular fetish find pregnancy not-at-all unappealing sexually once they start having kids.
All in all, I see pregnancy the same way I'd imagine a straight woman sees a really fit, muscular dude. Using your body's main sexual attributes to their fullest potential.
darker viewpoint, less "she has been betrayed" as OP said, and more "she's in an inescapable, extremely feminine predicament, and has nothing to blame other than her own horniness and lack of caution (unless her partner is an absolute tool), and, at her core, enjoys it in spite of the negatives. And at the end of it, she'll have to go through one last massive struggle to finally free herself of the situation she's gotten herself into."