The difference between talking with Henry about a baby when I was pregnant back in May and June (when he was ~17 months old) versus now (when he’s 21 months old) is drastic. Back then, he gave no indication that he understand what we were talking about at all. Now, he initiates conversations about the baby and adds his own thoughts. 

The first thing he said about babies is that they “cry.” He sings “The Wheels on the Bus” at school, so he knows that babies go “wah, wah, wah.” He even does hand gestures to go with it. After a while, he added to the conversation that babies “poop.”