I bought 0-3 and up but my son had came 6 weeks early so I had to go buy preemie and newborn also lol

Both. I did buy more 0-3 then newborn though, just from experience. My first baby wasn't in newborn very long

I bought Preemie all the way up 12 month in clothes and Preemie up to 3 in diapers

Both. Although my daughter was born into 3mo +.

I bought both the newborn my son was in for a month

A few newborn but mostly 0-3

I got both. But pampers does it based on the weight, not the age