i was so impressed with this onesie! i was worried they weren’t going to fit my little guy because i got a size 3m and he is 4m (and biiiig for his age) but they are perfect i 100% believe they last through growth spurts and am excited to pass down to a friend or our next baby one day. i also LOVE the sweet little pop of color—feels like i can pair it with everything! Note: I rated “runs large” since it would be a bit roomy if he was a 3m old or smaller for his age. I really appreciate this sizing because so many onesies are sized so tiny that by the time you get to that month and try it one, it doesn’t fit—not the case here!