Family Matters

Mom’s Saliva Can Strengthen Babies’ Immune Systems

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Getty Images/OJO Images RF / Getty Images/OJO Images RF

Picking up a dropped pacifier and sucking it clean may help infants to be better germ fighters.

The practice not only protects babies from the nasty microbes on the floor, but passes on good bugs that can lower the risk of allergies, according to a new study from Swedish researchers published in Pediatrics. “Parental sucking of their infant’s pacifier is associated with a reduced risk of allergy development and an altered oral flora in their child,” they write.

Infants whose parents use their tongues to burnish binkies were more likely to have different strains of bacteria in their gut, and with more helpful bacteria populating the intestines, the less likely the babies were to develop allergies and eczema.

When the 184 infants in the study were four months old, the scientists collected saliva samples to determine which types of bacteria resided in their guts. At six months old, parents reported whether their infants used pacifiers and how moms and dads cleaned them. The researchers checked back in with the parents when their babies were 18 and 36 months old to see if the infants had developed allergies and when the first symptoms appeared.

(MORE: Bacteria on Binkies: A Recipe for Crankiness)

By 18 months, 25% of the babies had eczema, 15% had developed some type of food allergy and 5% had been diagnosed with asthma.

But the children whose parents sucked on their pacifiers to sanitize them were one-third less likely to have eczema, which is considered the earliest sign of allergies, at 18 months than kids whose parents relied on other techniques — such as rinsing the binkies in tap water or boiling the pacifier. By the time the kids were 3 years old, those who had their pacifiers sucked clean were still considerably less likely to develop eczema than kids whose parents employed other cleaning strategies.

And it didn’t seem that parents were passing on more germs or infections to their little ones with the practice; regardless of how a parent cleaned a pacifier, all of the babies in the study developed an average of one and a half colds in their first six months of life.

To delve even deeper into the power of parents’ saliva, the researchers also looked for correlations between how a mother delivered her child and her tendency to suck the pacifiers clean. Moms who delivered vaginally tend to favor the cleaning practice more than C-section moms. (Those with a college degree, meanwhile, were less likely.) Indeed, vaginally-delivered babies are already exposed to more maternal bacteria thanks to their transit through the birth canal; tack on the oral bacteria from a parent’s mouth and babies in this group had the lowest incidence of eczema: 20%. C-section babies whose parents didn’t lick their pacifiers had the highest rate — 54% — of eczema.

So while it might seem unsanitary, sucking on that pacifier may end up giving babies just the right kind of good germs to better equip them to battle the more dangerous ones.

(MORE: Bring Back the Binky? Study Finds Pacifiers Actually Boost Breast-Feeding)