Final answer:
Newborns regulate their body temperature soon after birth through a process called nonshivering thermogenesis, which involves the breakdown of brown adipose tissue or brown fat. This helps them maintain their body temperature in a cooler environment. They also have a higher ratio of surface area to volume, limited ability to generate heat, and little subcutaneous fat.
Step-by-step explanation:
Newborns regulate their body temperature soon after birth through a process called nonshivering thermogenesis, which involves the breakdown of brown adipose tissue or brown fat. Brown fat is distributed over the back, chest, and shoulders of newborns. It differs from white fat in that it generates heat instead of storing energy. This process helps newborns maintain their body temperature in a cooler environment.
Newborns also have a higher ratio of surface area to volume compared to adults, which means they produce heat more slowly and lose it more quickly. They have limited ability to generate heat by shivering due to immature musculature and cannot quickly constrict superficial blood vessels in response to cold. Additionally, newborns have little subcutaneous fat for insulation.
These factors make it harder for newborns to maintain their body temperature, and they rely on nonshivering thermogenesis as the primary method to regulate their body temperature after birth.