baby hair

Samantha
My son slept in his Mamaroo for a solid 2 months at night. He is now 2.5 months and has been doing great sleeping in his crib. My question is since he slept in a "swing" when will his hair grow back?
**yes he's sleeping on his stomach and don't judge because it's not all the time & that's not what I'm inquiring about. No the wet is not my sweat it's his drool lol