To help understand this better, we need to know that these cute baby clothes come in roughly three groups; that is (a) the infants, (b) the babies, and (c) the toddlers. Therefore, depending on these categories you can decipher between the growth and the need of changing the baby's clothes, where an infant fits into between 0-6 months, babies that are bigger than the infants in between 6 to 12 months, and 12 months and above that fits on the toddlers.