I’m with the minority who don’t really get the point. Mostly because, complications aside, I’m really not sure what the issue is with standing. Obviously I’d rather sit down, but that’s true when I’m not pregnant.
This isn’t a “pregnancy isn’t an illness” thing - of course if you feel shit do what you need to do, wear a badge, be assertive, get a seat.
I’m nearly 38w, and commuting, but I’m lucky, active and basically feel fine so haven’t bothered with a badge. People offer me seats (there’s no mistaking me for chubby at this stage), which is really kind and I appreciate it but I’ve yet to feel so desperate to sit down that I need it. As I say, lucky.
As a side note, the only time I’ve felt my big bump being actively ignored is by the occasional woman with a badge, marching over (looking very mobile, flat of stomach and firm on her feet) and barging past my hippo-like form for her seat entitlement. It’s possible on the few occasions this has happened they had terrible nausea, dizziness and so on. It’s also possible they were absolutely fine and just a tiny bit self absorbed and entitled and were using pregnancy as a justification for that.