Overview
Why a Newborn Becomes Cold Quickly
A newborn loses heat rapidly because the body has a large surface area relative to its mass, thin skin, little insulating fat, and limited ability to shiver.
A newborn loses heat rapidly because the body has a large surface area relative to its mass, thin skin, little insulating fat, and limited ability to shiver. Instead, the infant relies on non-shivering thermogenesis, which uses brown fat to generate heat. That response consumes oxygen and glucose. The four routes of heat loss are easy to connect to what the nurse sees: - Evaporation: fluid on the skin cools the infant, especially immediately after birth or bathing. - Convection: moving cool air carries heat away. - Conduction: contact with a cold scale, mattress, towel, or hands transfers heat from the infant. - Radiation: heat moves from the infant toward nearby cold surfaces, even without direct contact. A wet, uncovered newborn in a cool room can therefore become cold within minutes. The quiet infant with a weak suck may be experiencing cold stress rather than simply being sleepy. Increased respiratory effort, reduced tone, poor colour, jitteriness, and poor feeding are concerning because they may reflect rising oxygen and glucose demands.