Most data collectors considers the first 28 days after birth as the newborn period. It is more an artificial label than a real period. Some would label the infancy period as being from birth to the point of walking. Most data collectors considers the first 28 days after birth as the newborn period. It is more an artificial label than a real period. Some would label the infancy period as being from birth to the point of walking. In brief: Wording issue. Most data collectors considers the first 28 days after birth as the newborn period.