Pregnancy doesn't make my body public property

I don't know why people assume that because a woman is pregnant, they have the right to touch her body UNINVITED. They do not. So far, this has only been a problem with male friends (maybe the female ones are smarter?). If it isn't appropriate when I'm not pregnant, it certainly doesn't magically become so when I am. It is doubly inappropriate from friends with whom you do not have a friendship that is physically expressive. Now, everyone has some friends who DO express their affection physically (in the NICE way - hugs, etc.), but the belly is not even part of that. If everyone was touching my shoulder because I was pregnant, it wouldn't bother me. But the belly (especially the lower belly) is not an area that is normally handled by anyone but my GP and my husband. I can understand people might want to feel a baby kicking, but honestly, I am very obviously parked in the first trimester right now, and I can tell you that the baby is only just starting to form bones. Even if I had a giant belly complete with motile baby, I would expect that friends would have enough respect to ask before touching, and to accept whatever answer I gave. The next person who greets me by hunting for my uterus with their fingers, will get their fingers broken. I am dreading running into people that I have told on the phone, because I am worried they will try to take liberties when they see me in person. My patience is wearing thin, and I know that the next person who crosses this line will be the recipient of my frustration, and perhaps also the aforementioned shattered digits.
There was a little ditty we learned in grade school that goes something like this:
"My body's nobody's body but mine/You run your own body/Let me run mine". There was also an accompanying video (and a set of steps like "Say no, go, tell someone!"), but I think the song is sufficient.