Final answer:
Swaddling an infant with hyperbilirubinemia during phototherapy puts them at risk by limiting UV light exposure needed to break down bilirubin.
Step-by-step explanation:
A nursing action that would put a 3-day-old infant receiving phototherapy for hyperbilirubinemia at risk would be to swaddle the infant to maintain body temperature. Swaddling the infant would be counterproductive as it would restrict the exposure of the infant's skin to the UV light, which is necessary to break down the excess bilirubin. It is essential to keep the eyes and genitalia covered to protect them from UV light, while feeding the infant every 2 hours supports hydration and bowel movements, which can aid in reducing bilirubin levels. Allowing the parent to hold the infant also does not interfere with therapy, as long as phototherapy is not disrupted for extended periods.