How exciting to grow up
When children grow up, they mark their progress by going through grades; they graduate from kindergarten, elemantary school, etc.
But for infants, it is a whole different story. I believe that the main milestone for an infant's progress in life is the way she graduates from each diaper size. There is nothing more exciting than leaving the puny little size 1 diaper behind and embracing a more manly size 2. Currently I am at size 3, which is impressive for a 3-4 month old. But hey, don't make any judegements about my size, it is a free world, at least until I go to school.