Pacifiers sucked clean by parents linked to less allergy

Researchers at Queen Silvia Children's Hospital in Gothenburg followed 184 infants from birth, recording which parents cleaned a pacifier by sucking it themselves versus rinsing it or boiling it.

By 18 months, infants whose parents sucked the pacifier clean had lower rates of asthma and eczema, while a drop in allergic sensitization was too small to be statistically clear. The protective effect against eczema was still measurable at 36 months, alongside a similar benefit linked to vaginal birth.

The researchers suspected the mechanism was microbial: saliva from an adult's mouth is a very different exposure than a rinse under tap water, and it may nudge an infant's developing immune system and oral microbiome in a protective direction. The sample was small and the practice sounds unappealing to many parents, so the finding has mostly shaped hygiene-hypothesis research rather than any pediatric recommendation to suck on a child's pacifier.

Saliva may have been doing something right.