At Happy Heinys we understand that most One Size diapers will never fit a newborn and that is why we have designed our Mini One Size for you. What is best about our Mini One Size is that it is not just for the newborn weeks. You can use this diaper from 4-15 lbs which for some babies can be 6 months-1 yr. This will help to get you through those early tricky weeks when most babies leak through all one size diapers.