Super insensitive MIL or am I reading too much into it?

TW: living child

My MIL has probably guessed we are trying for our second (because we’ve both always said we want lots of children and for them to be close in age). We went to the farm with our toddler and PILs and right as the entrance to the farm there is a giant sign about pregnant women not coming in to avoid toxoplasmosis. MIL approaches the sign, pauses and shouts me “SARAH!! SARAH!! Have you read this sign?” I have given no indication and she doesn’t know we are doing IVF. I didn’t even know how to respond so just said “yep I’ve seen it”. What would you have said?