Which of the following complications is likely to arise in a newborn with low body temperatures?

A newborn with low body temperatures is at increased risk for hypoglycemia. When a baby's body temperature drops, it can lead to increased metabolic demands as the body tries to generate heat. This is particularly critical for newborns, who are already vulnerable due to limited glycogen stores. The body utilizes stored glucose to generate heat, and if the newborn cannot maintain their temperature adequately, the consumption of glucose may exceed what is present in the bloodstream. This results in hypoglycemia, where the blood sugar levels become dangerously low.

In contrast, increased urine output, rapid weight gain, and persistent lethargy are less directly connected to low body temperatures. Increased urine output may vary depending on other factors but is typically not an immediate concern resulting from hypothermia. Rapid weight gain tends to be associated with feeding and fluid retention rather than directly linked to temperature regulation issues. Persistent lethargy, while a concerning symptom, can stem from a variety of conditions and is not uniquely tied to low body temperatures in the same way that the risk of hypoglycemia is. Thus, the connection between low body temperatures and hypoglycemia underscores the critical need for careful monitoring of newborns' temperatures and blood glucose levels.