Just One.

Kenley: "Mom, do you have a baby in your belly anymore?"
Me: "No, not anymore. That baby was Adley, remember? Am I allowed to have another baby in my belly again?"
Kenley: "Yeah, but just one baby. Not two babies."
Me: "Oh, so only one baby then?"
Kenley: "Yeah. Jade is one, Ivan is two. Just one baby."

Baby Belly.

Following an explanation of a baby shower...

Kenley: "I got a baby in my belly."
Me: "Oh yeah?  How'd you get a baby in your belly?"
Kenley: "Daddy."