Could you approach your line manager to let them know this repeated behaviour has an impact on you? It's not appropriate to ask generally, but certainly not in the workplace.
Regardless of anyone’s appearance, its absolutely not appropriate to ask if they are pregnant or planning to get pregnant! You could let your manager know, or try and put it back on them and say ‘thats extremely impolite of you’ or ‘what an extremely inappropriate question’ to make them embarrassed. So so rude ❤️
I really struggle with people asking if someone’s pregnant off the cuff, especially by looking at someone’s body. They don’t know yours or anyone else’s situation, someone else could be struggling to get pregnant and get upset overhearing people being so blasé about asking. I’d be really blunt and say “I’ve told people before I’m not pregnant so I don’t appreciate the question again & again, please let’s drop it”. I wouldn’t let them get to you but I think being blunt and straight will maybe shut them up. X