Somebody forgot to remove the pregnancy belly prop from Angela before she is handed the babies in bed -- her belly is a big as when she came in. This is not a goof. Any woman having just given birth to four human beings, or even one human being, her belly would not deflate like a balloon. She still has swelling, possible afterbirth, water retention. Women often still look pregnant at various stages weeks after the delivery.
The four babies are too big to be newborns. These quadruplets should have been far smaller than they were here and appear to be several months old.