How long does the infant stage last according to the definitions provided?

The definition of the infant stage typically recognizes this period as lasting from 1 month to 12 months old. This timeframe aligns with common developmental benchmarks used in pediatrics and childcare practices, where significant growth and developmental milestones occur during the first year of life.

Newborns, typically defined as those from birth to 1 month, transition into the infant stage starting from around 1 month, continuing until they reach 12 months of age. During this period, infants undergo rapid physical, cognitive, and emotional development, which is crucial for their overall health and well-being.

The other choices extend the definition of the infant stage beyond the established parameters, either by starting too late or extending too long into the toddler stage. For instance, defining the infant stage up to 2 years would encompass the early toddler developmental stages, which are characterized by different growth and behavioral patterns.