HI,
I am pregnant with my fourth. My 4 yr old daughter says she has a baby in her belly too, sometimes alot in one week, sometimes not at all, so does my 4 yr old neice, too. My sister seems to be makin a bigger deal of her daughter saying it than I am of mine. It's a phase, they are young and trying to understand what is going on. I just laugh and giggle and tell my daughter, you can't have a baby, you;re still little or you can have one when you grow up and get married, or in ur case, only girls can have babies in their bellies. But realize they are just adjusting and will understand in their own time. Try not to overdo it with trying to force him to understand too much too soon.
I ask my daughter if she will be my helper with her little brother on the way,, seems to make her feel included and important. My older two went thru the same thing as well.
My daughter also goes to every appt I have, she likes to hear the 'baby heart', lol.
It will all work out and your son will be a normal little boy, just love him with all you have. Kids are the cutest and say the funniest things too.
Take care and God bless,
L.
P.S. CONGRATS ON THE NEW ONE !!!