Thanks to my mother, not a single cardboard box has found its way back into society. We receive gifts in boxes from stores that went out of business twenty years ago.
People shop for a bathing suit with more care than they do a husband or wife. The rules are the same. Look for something you'll feel comfortable wearing. Allow for room to grow.
One thing they never tell you about child raising is that for the rest of your life, at the drop of a hat, you are expected to know your child's name and how old he or she is.