Which of the following conditions in a newborn should prompt immediate evaluation for potential respiratory distress?

Grunting during expiration in a newborn is a significant sign that should trigger immediate evaluation for potential respiratory distress. This noise typically occurs when the infant attempts to increase end-expiratory pressure to improve oxygenation and is often associated with respiratory issues such as pneumonia, hypoxia, or other underlying lung conditions. Grunting indicates that the newborn is in respiratory distress and struggling to breathe effectively, which warrants urgent medical assessment and intervention.

In contrast, abdominal breathing with intermittent pauses is a common and normal finding in newborns and often does not indicate distress. Likewise, respirations of 50-60 breaths per minute are within the normal range for a newborn, as they can typically breathe 30-60 times per minute in a resting state. Hiccups are also a normal occurrence in newborns and are typically not a cause for concern, often resolving on their own.