What action should the nurse implement to prevent conductive heat loss in a newborn?

To effectively prevent conductive heat loss in a newborn, using a blanket on the scale when weighing the infant is a successful approach. Conductive heat loss occurs when the baby comes into contact with a colder surface, drawing heat away from its body. By placing a blanket on the scale, the nurse creates a barrier between the newborn and the cold surface of the scale, thereby reducing the risk of heat loss through conduction.

In the context of the other options, placing the infant under a radiant warming system primarily addresses convective heat loss by providing a warm environment, rather than preventing conductive heat loss directly. Using a warmed blanket to dry the newborn is beneficial for preventing both conductive and evaporative heat loss but is not specifically tailored to the situation of weighing the infant. Positioning the crib away from windows can assist in maintaining an ambient temperature but does not directly address conductive heat loss when the infant is on a cold surface like a scale. Thus, using a blanket on the scale is the most direct and effective action for minimizing conductive heat loss during weighing.