Is it true that babies are born with the ability to swim? In short. NO. A reflex called the bradycardic response makes babies hold their breath and open their eyes when submerged in water, says Jeffrey Wagener, a pediatric pulmonologist in Colorado. This response is part of the mammalian diving reflex. When the face of an infant is exposed to cold water, the heart slows down and blood is shifted away from the peripheral muscles to conserve oxygen for the brain and heart, and they typically hold their breath. Also, until around 6 months, babies placed in water tummy down reflexively move their arms and legs in a swimming motion, which makes them look like natural swimmers.