How do I get people to stop trying to put their hand on my stomach?

I’m 6 months pregnant and everytime someone sees me I guess they just have the urge to touch my stomach. Even complete strangers! I find it very uncomfortable and rude when random people just put their hand on my stomach especially without asking. One day I think i’ll have a mom instinct and just accidently hit someone. Lol. How do I get people to stop doing this?

I told my mother-in-law I didn’t like it, and she still does it! It really annoys me.