Babies have a natural “diving reflex” or “mammalian dive reflex” that can help them hold their breath and momentarily reduce their heart rate when submerged in water. This reflex is most pronounced in infants and typically starts to fade around 6 months. However, it’s important to note that this reflex is not reliable enough to ensure a baby’s safety underwater. The diving reflex may not be triggered consistently, and young children have not yet developed the skills to hold their breath voluntarily or for extended periods.