I sometimes see women so overweight here that it’s not even clear from them that they are pregnant, I have a question why do you need her to be pregnant, does pregnancy play any role?

Knowing that girl is pregnant is already somewhat of a turn on, even if she isn't visibly pregnant yet. However, it's the physical changes of her body that make it so much more appealing, especially her belly. Some may not agree, but the belly really is the centerpiece of the pregnancy fetish in my opinion. Plus sized women don't really get to have the "pregnant belly" that a regular sized woman would because their bodies are too big for their bellies to get disproportionately bigger.

Unless I'm having sex with her I wouldn't care. If I am, her being pregnant could be the difference between wearing a condom or not, or pulling out vs. Cumming inside of her

How overweight are you talking? I like BBWs being pregnant because how huge their bellies get but I do have a limit on how big a woman is before I lose interest.