What immediate sign might indicate respiratory distress in a neonate?

Grunting is a significant sign of respiratory distress in a neonate. When a newborn experiences difficulty breathing, they may exhibit grunting as a means of increasing end-expiratory pressure and improving oxygenation. This sound is produced during expiration, often as a result of the infant attempting to expel air more forcefully to keep the alveoli open and facilitate gas exchange. It serves as a physiological response to the inadequate oxygenation or ventilation that the neonate is experiencing.

In contrast, other signs listed do not specifically correlate with respiratory distress. Pallor might indicate a range of issues, including hypoxia, but is not a direct or specific sign of respiratory distress. Fever may suggest infection or an inflammatory process but does not indicate immediate respiratory dysfunction. An increased appetite could suggest that the neonate is stable and not in distress, as feeding typically requires energy that a distressed infant might not be able to muster. Therefore, grunting is the most direct and relevant sign indicating respiratory distress in a neonate.