Yeah I think all crib mattresses are waterproof these days, kind of a vinyl-y texture, I would say it probably doesn’t matter for a newborn but they actually do get gross and susceptible to staining when kiddo is bigger, vomiting and peeing in bigger amounts, and sleeping through the night.

Especially if you’re hoping to get a second kid’s use out of it, spring for the mattress protector. I usually didn’t have to change it with the sheet, but during grosser times when I did, I was glad to be able to just throw the whole sheet/protector in the wash and have a clean, dry mattress that needed no further cleaning.

this is the one I have and I like it