You might think the idea of popping your baby's dummy in your mouth to give it a quick clean is a tad gross (or not if you're up to child number three), but according to new research, the way you clean your bub's dummy could actually reduce their risk of allergies.
"We found the children of mothers who sucked on the pacifier had lower IgE levels," said lead author and allergist Dr Eliane Abou-Jaoude. "IgE is a type of antibody related to allergic responses in the body. Although there are exceptions, higher IgE levels indicate a higher risk of having allergies and allergic asthma."
As part of the study, the preliminary findings of which were presented at the American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting, Dr Abou-Jaoude and her colleagues interviewed 128 new mothers about how their cleaned their baby's dummy.
Of the 58 per cent who reported using a dummy for their child, 41 per cent cleaned the dummy via sterilising it, 72 per cent hand washed them and 12 per cent cleaned them by popping them in their mouth.
And the results were surprising.
"We found that parental pacifier sucking was linked to suppressed IgE levels beginning around 10 months, and continued through 18 months," said co-author Dr Edward Zoratti.
The question is, why?
According to the research team, it may be due to the transfer of "health-promoting" microbes from the parent's mouth. "We know that exposure to certain microorganisms early in life stimulates development of the immune system and may protect against allergic diseases later," says Dr. Abou-Jaoude. "Parental pacifier sucking may be an example of a way parents may transfer healthy microorganisms to their young children.
What remains unclear, however, is whether the effect continues into later years.
Additionally, it's important to note that although the study shows an association between parents who suck on their baby's dummy and kids with lower IgE levels, it doesn't necessarily mean that doing so causes lower IgE.
But while the findings are interesting, Dr Abou-Jaoude says she is not suggesting parents start cleaning their kids' dummies by popping them in their mouths when they fall on the floor.
"We are not telling parents to clean their child's pacifier by sucking on the pacifier," she says. "Bad bacteria can be transferred by a parent sucking on the pacifier and then giving it to their child, exposing them to other infections."
Instead, Dr Abou-Jaoude says the takeaway message is this: the microbes babies are exposed to early on in infancy can affect their immune system development.
It's not the first time an association between sucking on bub's dummy and development of allergies has been noted. A swedish study published in the journal Pediatrics in 2013 found that parents who cleaned their kids' dummy by sucking it (after the age of six months old) were less likely to have asthma and eczema at 18 months than those who used other cleaning methods. The researchers also found that the "salivary microbiota" differed between parents who cleaned their dummies by popping them in their mouth and those who did not.
"Parental sucking of their infant's pacifier may reduce the risk of allergy development, possibly via immune stimulation by microbes transferred to the infant via the parent's saliva," the authors wrote at the time. But they also issued a strong caveat: "more research is needed to establish if parental pacifier sucking could be a simple and safe method to reduce allergy development in infants and young children."
Raising Children Network currently advises that babies under six months should use dummies that have been sterilised. From six months on, as children are more resistant to infections, parents can wash dummies with soap and water.