The decreased ability of the preterm neonate to produce heat to maintain normal body temperature is most related to

• A. Immature hypothalamus
• B. Lack of shivering reflex
• C. Limited subcutaneous tissue and brown fat stores
• D. High metabolic rate

Answer: (C)

Non-shivering thermogenesis using brown adipose tissue is how newborns generate heat. Preterm infants have very little brown fat and thinner subcutaneous tissue, so they lack the primary means to produce and retain heat. This makes maintaining normal body temperature particularly difficult. While an immature hypothalamus or absent shivering reflex can affect temperature regulation, they don’t account for the main limitation in heat production. A high metabolic rate would increase heat needs rather than explain reduced heat generation.