Neutrophil counts in newborns are higher under which condition?

• A. At higher altitudes
• B. When delivered via cesarean section without labor
• C. With decreased gestational age
• D. At sea level

Answer: (A)

Neonatal neutrophil counts rise in response to physiological stress. When the fetus experiences stress from hypoxia or the birth process, stress hormones like catecholamines and cortisol cause neutrophils to be released from the bone marrow and marginated pools into circulation. At higher altitude, chronic fetal hypoxia provides a sustained stress signal, promoting greater neutrophil mobilization and production, so newborns born at higher altitudes tend to have higher circulating neutrophil counts than those born at sea level. The other conditions don’t produce as strong or as consistent a stress signal to elevate neutrophils—cesarean delivery without labor, while affecting stress responses differently, and decreased gestational age often alters leukocyte patterns in other ways.