I got this originally in size 0-3 months but have just recently reordered in the larger size as I’m not 100% sure this will fit our newborn as is in a few weeks when she is born. I love these pants and I love the headband (you can untie to fit any baby head!). So all in all great just seems too small even for 0-3 for me the waist is elastic but still stretched fully is only about 8-10 inches around. So would be too tight on an umbilical cord if the baby is born on the bigger side of 7-9+ lbs. I also have washed these (in a lingerie bag to be safe) and they didn’t shrink or change at all for the wash or dry! So I love that!! In another note I am hopping the 6month size will not be a huge jump that it will swallow a newborn whole but will be more reasonable with the waist band to allow for baby fat.