What is the most critical physiologic change required of newborns at birth?
Correct Answer: A
Rationale: The correct answer is A: Transition from fetal to neonatal breathing. The onset of breathing is the most immediate and critical physiologic change required for the transition to extrauterine life. Factors that interfere with this normal transition increase fetal asphyxia, which is a condition of hypoxemia, hypercapnia, and acidosis. While body temperature maintenance, stabilization of fluid and electrolytes, and closure of fetal shunts in the heart are crucial changes in the transition to extrauterine life, breathing and the exchange of oxygen for carbon dioxide must take precedence as they are essential for newborn survival.