<P> Infant swimming is the phenomenon of human babies and toddlers reflexively moving themselves through water and changing their rate of respiration and heart rate in response to being submerged . The slowing of heart rate and breathing is called the bradycardic response . It is not true that babies are born with the ability to swim, though they have reflexes that make it look like they are . Babies are not old enough to hold their breath intentionally or strong enough to keep their head above water . </P> <P> Most infants, though not all, will reflexively hold their breath when submerged to protect their airway and are able to survive immersion in water for short periods of time . Infants can also be taken to swimming lessons . Although this may be done to reduce their risk of drowning, the effects on drowning risk are not reliable . It is extremely important to note that while babies can imitate swimming motions and reflexes, they are not yet physically capable of swimming . </P> <P> Most human babies demonstrate an innate swimming or diving reflex from birth until the age of approximately six months . However, babies this young cannot actually swim, due to their lack of body features and strength . Other mammals also demonstrate this phenomenon (see mammalian diving reflex). This reflex involves apnea (loss of drive to breathe), slowed heart rate (reflex bradycardia), and reduced blood circulation to the extremities such as fingers and toes (peripheral vasoconstriction). During the diving reflex, the infant's heart rate decreases by an average of 20% . The glottis is spontaneously sealed off and the water entering the upper respiratory tract is diverted down the esophagus into the stomach . 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, slowing the onset of serious hypoxic damage . The diving response can therefore be regarded as an important defence mechanism for the body . </P> <P> Drowning is a leading cause of unintentional injury and death worldwide, and the highest rates are among children . Overall, drowning is the leading cause of injury death among children aged 1--4 years in the United States, and is the second highest cause of death altogether in that age range, after congenital defects . </P>

When do babies lose the ability to swim
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