When buying Gerber products be aware that their clothing runs small. My son is 25 inches long, 12pds and 3 months old and he's wearing the 6-9 month onesies no problem. In another 2-3 months I'm betting he'll move to the 9-12 month ones and he'll not even be 6 months yet. It seems to me Gerber doesn't account for the 'fluff' of the diaper which is why the sizing is so off. Otherwise I LOVE their onesies and will just buy them in much larger sizes :)