Final answer:
The most critical step following birth is to assess the newborn's respiratory effort, which is part of the Apgar test that evaluates five criteria immediately after birth.
Step-by-step explanation:
The priority action that should be taken following birth during newborn assessment is to assess respiratory effort. This is critical as it determines the immediate medical needs of the newborn. The newborn's transition from the uterus to the outside world is evaluated through a test known as the Apgar test.
The Apgar test includes a quick assessment of five criteria: skin color, heart rate, reflex, muscle tone, and respiration. Of these, heart rate and respiration are the most critical and are assessed immediately. Apgar scoring is done at 1 minute after birth and again at 5 minutes after birth, and it helps healthcare providers determine whether a newborn is in distress and if immediate medical attention is necessary. A score below 5 is considered an emergency, while a score of 8 or above is normal.