Newborn and very young babies possess a number of reflexes, some of which they lose very quickly. These include the stepping, swimming and breath control reflexes. When a baby is plunged into water it reacts by closing its mouth and windpipe while making swimming movements. These automatic reactions disappear at the age of three to four months, and children can really only learn to swim when they are three or four years old.
The automatic stepping movements, which babies make when held upright with feet touching a flat surface, are also lost after three months. Only much later are the leg muscles and sense of balance sufficiently developed to enable the child to stand upright and walk. Other babyhood reflexes, such as swallowing, coughing and sneezing, are retained permanently.