Physical growth during infancy is faster than at any other age. By one year, the infant's birth weight should have tripled and height increased by 50% from weight and height at birth.

Newborns have surprising abilities, such as fixing upon and following human faces. Neurologic development progresses centrally to peripherally. Thus, newborns learn head control before trunk control and use of arms and legs before use of hands and fingers (Fig. 1).

FIGURE 1. Sitting up is a developmental milestone among infants.

Activity, exploration, and environmental manipulation contribute to learning. By 3 months, normal infants lift the head and clasp the hands. By 6 months, they roll over, reach for objects, turn to voices, and possibly sit with support. With increasing peripheral coordination, infants reach for objects, transfer them from hand to hand, crawl, stand by holding on, and play with objects by banging and grabbing. At 1 year a child may be standing and putting objects in the mouth (Fig. 2).

FIGURE 2. Children often take their first steps after one year.

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