A neonate is an infant in the first 28 days of life, a critical period in a newborn's adaptation to life outside the womb. Most crucially, a neonate's health depends upon adequate nutrition (through mother's milk or formula) and successful respiratory functioning. At birth in the United States, a neonate typically weighs 7-8 lb. (3.1-3.6 kg), and measures 19-21 in. (48-53 cm).

In the United States, a neonate's condition and stability is first measured with the Apgar test, which is administered during the first five minutes after birth. The Apgar test measures an infant's color, respiratory affect, cardiac effort, body tone, and responsiveness to stimuli. Each health sign receives a 0, 1, or 2, with a total score of 7-10 being average-to-good, a score of 4-6 signaling potential developmental difficulties, and a score of 3 or below indicating doubtful survival. An Apgar score is not necessarily a...