Final answer:
A newborn makes a critical transition from intrauterine to extrauterine life during the first 24 hours after birth, during which continuous health assessment is required.
Step-by-step explanation:
The critical transition from intrauterine to extrauterine life for a newborn occurs during the first 24 hours after birth. This time is crucial for the newborn's adaptation to the outside world, requiring continuous health assessment due to the significant physiological changes taking place. For example, the newborn's first breath is a vital event inducing significant changes in the circulatory system, marking the closing of cardiac shunts that were essential during fetal life. Also, the infant must establish effective thermoregulation and intake of nutrition, as well as adjust to a sensory environment vastly different from the womb. The assessment during this period includes monitoring for dehydration, checking the infant's reflexes which help in their survival, and ensuring that weight loss is within the normal range - a newborn typically loses a small amount of weight in the first week but should start gaining weight soon thereafter.