When Baby A was born, I couldn’t really judge whether he was big or small. Every time someone saw him though, they would say “he’s so tiny!”. I’m guessing that means he’s small.
Actually, I think I realised properly when I noticed how much extra space he has in his clothes – he had this habit of curling his hands and legs up so the sleeves and legs of his body suit would just hang loosely.
Here’s a picture of him doing his best pope impression.