Question: what is the difference between newborn size and 0-3 months?
Answer: “Newborn” (NB) represents an average baby at birth up to 21.5 inches long and five to eight pounds. ... If she's a big baby or hits an early growth spurt, you can exchange any extras for the next size up: 0 to 3 months, which usually fits babies anywhere between eight to 12.5 pounds.