The case for licking your baby's pacifier

Parents are used to getting conflicting information on, well, just about everything. To wit: For years, mothers and fathers have been warned against feeding their children from their own spoons, cleaning off a dropped pacifier with their mouths, or otherwise exposing a baby to parental saliva. And now, "new research may turn that thinking on its head," says Anahad O'Connor at The New York Times.

A study from Sweden's University of Gothenburg, published Monday in the journal Pediatrics, found infants whose parents sucked on dirty pacifiers had fewer allergies than parents who only rinsed or boiled the binky, plus less chance of developing eczema or showing symptoms of allergies. The children of pacifier-suckers also had less of a certain white blood cell that is tied to allergies and other health issues.

The study has a fairly small sample: 184 children, unusually prone to allergies — 80 percent had at least one parent with an allergy of some type. The researchers kept in contact with the parents from the birth, and examined the children at 18 months and again at 3 years. At six months, 136 of the infants were using a pacifier, and 48 percent of their parents sucked on a dropped pacifier to clean it (83 percent rinsed it with tap water, and 54 percent boiled the pacifiers; you could pick more than one option, but it's a safe bet the suckers and boilers have little overlap).

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At 18 months, the kids of the mouth-cleaners were 63 percent less likely to have eczema than their rinsing/boiling peers and 88 percent less likely to have asthma. By 36 months, the asthma effect had largely worn off but the children of binky-suckers still had a 49 percent lower chance of eczema.

The researchers, led by Dr. Bill Hesselmar, said that they couldn't prove that the parent's saliva was the cause of these beneficial results. But "the findings add to growing evidence that some degree of exposure to germs at an early age benefits children," says The New York Times' O'Connor, "and that microbial deprivation might backfire, preventing the immune system from developing a tolerance to trivial threats."

In other words, in the parenting conflict between those more prone to earthier "attachment parenting" — committed to promoting closeness between parent and child, famously through co-sleeping — and what we'll call "helicopter" parenting, or hovering over children and trying to keep them from all harm, this is a point for the attachment types. (Of course, germ-friendly parenting can go too far: See mail-order chicken pox–infected lollipops, for example.)

There are potential downsides to parents sharing saliva with their children — if mom or dad has cold sores/oral herpes, you could pass the virus to your child. And there are probably a lot of factors that affect allergies and asthma, especially vaginal birth versus C-section, Dr. Jennifer Kim, a pediatric immunologist and allergist at New York's Mount Sinai Hospital, tells ABC News. "Generally, what I tell families is don't change what you normally do based on the results of one study."

The main argument against cleaning off pacifiers in a parent's mouth has been that it can promote tooth decay in the infant or toddler — the bacteria Streptococcus mutans, which causes cavities, is highly contagious. But that's no reason to avoid sharing your child's spoon or licking off his or her pacifier, says Dr. Joel Berg, president of the American Academy of Pediatric Dentistry. You can't prevent your child from getting your germs, "unless you wear a mask or you don't touch the child, which isn't realistic," he tells The New York Times. It isn't smart either, given the beneficial enzymes, proteins, and other beneficial substances that your child gets. "Saliva is your friend."

"I think, like any new study, this is going to be challenged and questioned," Berg tells The Times. "But what it points out pretty clearly is that we are yet to fully discover the many and varied benefits of saliva."

"We know these bacteria are important for development," Dr. Wilfried Karmaus at the University of Memphis tells Reuters. But when it comes to cleaning a pacifier with the mouth, "we need a trial to be really sure that this is protective." If nothing else, this study should give parents permission to try the oral clean method without fear of harming their child, Karmaus adds. And that should be good news for every mom and dad. "Sometimes you take two or three pacifiers with you but if all are dirty and your child is crying, there's nothing you can do" but clean it yourself.