Four months?

We passed a large-bellied boy and Ma Debbo turned to Fatou Bobo and said, “Four months, do you think?”

At first I thought she was guessing his age, but that didn’t make sense because the kid was obviously much older than that. Then I realized she was joking that the kid was pregnant. I would’ve laughed to show her I got the joke, but first of all the timing would’ve been off and second of all, it just seems in poor taste to laugh at a malnourished child.