MIL asked me to unzip my jacket at a restaurant to see my pregnant belly

I’m 5 months pregnant and not close with my MIL at all.

Last time we saw her, we were sitting at a restaurant and she asked if my belly had gotten bigger. I was wearing an oversized jacket, said yes, and then she asked me to unzip it so she could see… right there at the table.

I went along with it in the moment, but afterward I felt super uncomfortable. It honestly made me feel like I was on display or something.

Now I’m worried about what comes next because I have a strong feeling she’s going to want to touch my belly at some point. The problem is I really don’t like being touched by people in general, I’ve always been this way (I don’t even like massages), so this isn’t new.

I don’t want to be rude, but I also don’t want to feel uncomfortable in my own body. How do I shut this down politely if/when she asks to touch my belly?

Would appreciate any advice, especially if you’ve dealt with boundary issues like this.