Scientists from the Hebrew University of Jerusalem found that maternal antibodies do more than protect newborns in early life; they help program long-term immune responses in the mouth.

Newborn baby

The study, led by Prof. Avi-Hai Hovav and DMD/PhD student Reem Naamneh at the Faculty of Dental Medicine, focused on the period after birth when the baby’s mouth is first exposed to large numbers of microbes. They identified two key pathways of maternal immune transfer: antibodies passed during pregnancy and antibodies delivered through breast milk. These two systems play very different developmental roles.

The most significant finding involves antibodies transferred during pregnancy, known as IgG. These antibodies reach the infant’s salivary glands and enter saliva, where they help set immune behaviour. According to the researchers, they “teach the immune system to remain calm in the presence of friendly bacteria while preparing it for future threats”.

In laboratory models, offspring that lacked these prenatal antibodies developed overactive immune responses, higher bacterial levels in gum tissues, and a greater risk of periodontitis in adulthood. This suggests that early immune “instruction” may influence disease risk decades later.

Breast milk antibodies served a different function, helping build and regulate the oral epithelial barrier. They control what the researchers describe as “barrier sealing,” ensuring the mouth’s protective lining develops at the right time depending on microbial exposure.

Hebrew University Jerusalem

The study also found that when these antibodies were disrupted — particularly through antibiotic exposure — the integrity of the oral barrier was weakened, leaving the mouth more vulnerable during early development.

Researchers also discovered that maternal antibodies specifically target harmful oral bacteria, including members of the Pasteurellaceae family, which are linked to aggressive forms of gum disease.

One of the most important potential applications is maternal vaccination during pregnancy. The researchers suggest that strengthening specific antibodies in expectant mothers could help “pre-program” the infant immune system to better control harmful oral bacteria, potentially reducing lifelong risk of gum disease such as periodontitis.

The study also suggests that antibiotic use during breastfeeding or infancy may unintentionally interfere with how breast milk antibodies help build and stabilize the mouth’s protective lining. This could lead to more careful and targeted use of antibiotics during these sensitive stages.

The study was published in the peer-reviewed Nature Communications.