I find it funny that this series will drag it's feet for like 150 chapters going over every minor conversation but then suddenly skip what should be a dramatic moment with a bunch of characters and just have sou give us a play by play instead.
Waaa is the baby crying right after being born I think. Kind of like how yuri talks out loud when she's in her own head, aya is playing out the scene and satou's close enough to hear it