Newborn babies don’t shiver. It turns out, they just don’t need to.
Older children and adults shiver when they’re cold as a way to create heat. Shivering causes muscles to expand and contract really quickly, which in turn, creates warmth. But babies have more of a type of fat that keeps them warm instead.
This brown adipose tissue, a.k.a. brown fat, burns calories and releases heat. Babies have this fat around their necks, chests, backs, and butts and it acts kind of like a big scarf to keep them warm.