From the pattern:

“After seeing this story about an OBGYN who knits hats for the newborns he delivers, I was inspired to create a hat similar to some he knits. I made this hat to fit a newborn about 6-8 lbs, but if you roll up the brim it fits smaller babies, and if you add a few more rows before decreasing it stretch to fit 8-10 lb baby. Works for boys or girls depending on the colors you choose.”