No touchie!

Dee🤓 • Had my boy Dec. 16th 2015 after having three miscarriages. Now I am pregnant again, after another miscarriage, so hopefully this one sticks. Due October 16th!
I have a problem being touched. Even by people I know and trust. So how do I gently tell people "don't touch my stomach!" I don't want to be rude, but I'm starting to show and I've already had some people start reaching out to touch. Some I trust enough to let them know I have a problem with being rubbed or touched. Others, like at church, just touch, and I don't want to scream at them, but at the same time I do. How have you told people, "no touchie"? With out coming off as rude?