Why ‘cleaning’ a dropped pacifier with your own mouth might benefit baby

“We found the children of mothers who sucked on the pacifier had lower IgE [immunoglubin E] levels,” says Dr. Eliane Abou-Jaoude, the study’s lead author and a fellow at the Henry Ford Health System in Detroit.

The body produces the antibody, IgE, when the immune system overreacts to an allergen, which can then cause an allergic reaction. Higher IgE levels indicate a higher risk of having allergies and asthma, according to Abou-Jaoude.

The researchers interviewed 128 mothers of infants over the course of 18 months for the study. Of the 128 mothers participating in the research, 58% reported that their child currently used a pacifier. Within that group, 4% of respondents reported cleaning their child’s pacifier by sterilizing it, while 72% said they hand washed it, and 12% reported they sucked on it.

Only nine babies in the study had mothers who reported they sucked their children’s binkies clean. But compared with the other children, those nine showed significantly lower levels of IgE, starting at around 10 months old. No fathers were included in the research.

The study has yet to be peer-reviewed and officially published, and its small sample size and short length of 18 months make it difficult to draw too many conclusions about long-term health outcomes, the researchers note. Other factors in addition to mom’s saliva could have developed the children’s immune systems.

“What’s very, very important to realize is that this was not a cause and effect study, Abo-Jaoude tells CNN , noting that more research is needed to examine the possible correlation. “This is not telling you, if you suck on your child’s pacifier, they will not develop allergies.”

Still, the study does suggest few risks to cleaning a baby’s pacifier with your own mouth, and the findings contribute to a growing body of research that indicates early exposure of microbes in babies may prevent allergies in children.

“The idea is that the microbes you’re exposed to in infancy can affect your immune system’s development later in life,” Abou-Jaoude says.

A 2014 study conducted by scientists at the John Hopkins Children’s Center showed a link between early exposure to bacteria and a lower likelihood of developing allergies and asthma. Infants in the study who were exposed to pet and rodent dander, as well as a wide variety of household bacteria, in the first year of life appeared less likely to suffer from allergies, wheezing and asthma.

The study also found the earlier the exposure the better — children who encountered such substances before their first birthday seemed to benefit rather than suffer from that exposure, while the same benefits were not seen if the child’s first encounter with these substances occurred after age one.

The study, published in the Journal of Allergy and Clinical Immunology , suggests that early exposure to bacteria and certain allergens may have a protective effect by shaping children’s immune systems — findings that are consistent with the so-called hygiene hypothesis, which states that children who grow up in very sterile environments may develop hypersensitive immune systems that make them prone to allergies.

Additional 2017 research from an Urban Environment and Childhood Asthma (URECA) study showed a lower risk of asthma at age seven for children in homes with higher levels of cat, mouse and cockroach allergens in the first three years of life. Previous research has also shown that children who grow up on farms, and thus have regular exposure to the microorganisms present in farm soil, also have lower allergy and asthma rates.

Despite the body of research, no one can say for certain whether pet dander or sucking on binkies will ensure your child an asthma and allergy-free future, but early exposure to household bacteria may help more than hurt.