Here's Finley at 2 weeks old and 4 months old. In the first shot, he's in a 0- to 3-month sleeper. By coincidence, my brother and sister-in-law gave us the same outfit in a 9-month size. Yes, my 4-month-old is almost too big for 9-month baby sizes.
Just think what would happen if we all kept growing at this rate. Yikes!