It’s important to keep babies warm from the inside out. Start with a wonderful meal. For babies, this would likely involve breast milk or formula to provide plenty of fluids. Proper nutrition is needed for their bodies to work at their optimum to stay warm. For clothing, the rule of thumb recommended by the American Academy of Pediatrics is to add one more layer to your baby than you would use for yourself. I also think it’s important to adjust the coverings in a warm car, etc., to prevent sweating. Since most baby underclothing is made of cotton, we have to be careful—sweating in cotton will cause significant heat loss when re-exposed to the cold air outdoors. Babies have a greater percentage of surface area than older children and adults and lose heat much faster so mittens and socks are necessary, and they need a hat to top it all off.
—Wendy Anderson-Willis, MD, FAAP, pediatric expert at Nationwide Children’s Hospital in Columbus, Ohio