Why might a preterm newborn struggle to maintain thermoregulation?

• A. Excessive body fat
• B. Lack of brown fat
• C. High metabolic rate
• D. Large body surface area

Answer: (B)

Preterm newborns often struggle with thermoregulation primarily due to the lack of brown fat. Brown fat is crucial for thermogenesis, as it helps generate heat in response to cold environments. Full-term infants have sufficient brown fat stores that develop during the third trimester, allowing them to maintain body temperature effectively after birth. However, preterm infants are born before they have developed these essential fat stores, leaving them vulnerable to heat loss and hypothermia.

While other factors, such as a high metabolic rate or a large body surface area, may play roles in thermal regulation, they are not as crucial as the presence of brown fat. A high metabolic rate can increase energy expenditure, but without adequate stores of brown fat to convert this energy into heat, preterm infants remain at risk. Similarly, although a large body surface area can lead to increased heat loss, it is ultimately the insufficiency of brown fat that most directly impacts the ability of preterm infants to thermoregulate successfully.