A woman is pregnant. A father is carrying his child in his arms. There is a child being pushed in a stroller. Then it happens. A stranger or passerby decides that they are a part of your family and will engage you in conversation. The conversation is just a ruse to try and touch the pregnant woman's stomach or the child you are holding. I do not understand the logic. I do not understand what makes people think they can invade your space and touch your stomach or child.
I did not put a sign on my wife's pregnant belly inviting people to touch it. I do not ask people to touch our son in any way. Quite the opposite - I try and make sure it does not happen. It is not your fetus. It is not your child. Do not touch.
If anything, a person should take extra precautions not to touch a pregnant woman or a baby in a stroller. Keep their disgusting germs away. We do not know where your hands have been, no do you know if our son is carrying something contagious. Most important of all - it is not your family, it is not your child. Keep your hands away. Period.
I have an issue when it comes to personal space and I do not like someone (other than my wife, son, or dog) getting too close and familiar. I dislike it even more when someone feels that they can just reach out and touch a member of my family without an invitation or permission for that matter.
My suggestion is as follows - respect other people's boundaries. Do not feel that you can touch any baby walking on the street just because you want to. I would much rather see you keep your hands away so I do not have to tell you to do.