Human babies demonstrate an innate swimming or diving reflex from birth until the age of approximately six months. Babies immersed in water will spontaneously hold their breath, slow their heart rate, and reduce blood circulation to the extremities. During the diving reflex, the infant's heart rate decreases by an average of 20%. The diving response has been shown to have an oxygen-conserving effect, both during movement and at rest, oxygen is saved for the heart and the lungs. The diving response can therefore be regarded as an important defense mechanism for the body.
Learning begins at birth; this can be seen in the process of teaching a baby to swim. As a baby develops these mobility functions, breathing will become deeper, more regular, and more mature. This enhanced respiration helps the baby to be able to make sounds, which improves communication and overall language development. When the baby can move better, and breathe better, health also improves. When the baby is able to communicate better with mom and dad, baby is happier. It is easy to see that these are all valuable “side-effects” of swimming.
Children who swim from a young age are sometimes more than a year ahead of their peers in their cognitive and physical development. In children studied, results surpassed expectations and indicated swimming children had an advantage when starting school. They were anywhere from six to 15 months ahead of the normal population when it came to cognitive skills, problem solving in mathematics, counting, language and following instructions. On average, swimming children were 11 months ahead of the normal population in oral expression, six months ahead in mathematics reasoning, and two months ahead in brief reading. As well as achieving physical milestones faster, the swimming children also scored significantly better in visual-motor skills. They were significantly better than the normal population in story recall (17 months ahead) and understanding directions (20 months ahead).