It's an old joke in parenting: you boil the pacifier for your first child, run it under water for your second, and just brush it off for your third. It turns out that the perceived laziness of experienced parents may actually be closer to what keeps babies the healthiest. In 2013, Swedish researchers at the Sahlgrenska Academy in Gothenburg reported that babies whose parents cleaned their pacifiers with their mouths were significantly less likely to develop allergies like asthma or eczema. The researchers followed 184 children from birth and kept tabs on how each baby's parents cleaned their pacifier, if they used one. If the pacifier fell on the floor, most parents cleaned it under running water. Some boiled the pacifier to remove all germs, and others did seemingly the opposite: they sucked on the pacifier to clean off any debris before putting it back in their baby's mouth. Surprisingly, at age one and a half, the children whose parents regularly sucked on their pacifiers were three times less likely to suffer from eczema, as well as less likely to experience asthma. Once the children hit three years of age, the protection against asthma seemed to disappear, but they were still less likely to develop eczema. Learn more about why bacteria can be beneficial in the videos below.