Final answer:
Birth weight is the best predictor of a child's health in the first year of life, as it is a strong indicator of a newborn's current health and nutritional status and their risk for future obesity.
Step-by-step explanation:
The best predictor of a child’s health in the first year of life is birth weight. At doctor visits, a baby's weight and length are measured and compared to standard values to assess normal growth. A baby who grows too slowly may have health problems or be undernourished, while a baby with a faster-than-normal weight increase may be at risk of obesity later in life.
A well-nourished, full-term newborn is expected to have an average birth weight of 3.4 kg (7.5 lb) and an average length of 51 cm (20 in.). The newborn typically loses a bit of weight in the first week but should then start gaining weight rapidly.
Other assessments, such as skin color and head circumference, are important but do not directly predict a child's health as reliably as birth weight does for the first year of life. After birth, five criteria—skin color, heart rate, reflex, muscle tone, and respiration—are assessed to indicate the neonate's transition from the womb; this is separate from ongoing health predictions.