Study shows how saliva could reveal mental health struggles during pregnancy

The study, published in BMJ Mental Health, is the first to examine the link between the oral microbiome—microorganisms in the mouth and throat—and maternal mental health. Researchers discovered that saliva samples from pregnant women experiencing high stress or mental health symptoms showed significant differences in microbial diversity compared to those with fewer or no symptoms.

Joseph Lonstein, professor of psychology at Michigan State University and lead researcher, explains:

Positive mental health is crucial for mothers’ well-being and their ability to sensitively care for infants. We hope our study will stimulate future research on how microbes in and on our body, other than those in our gastrointestinal tract that are already often studied, are associated with mental health in mothers and even people who are not mothers.

The study analysed saliva samples from 224 women in their second trimester as part of the Michigan Prenatal Stress Study. Participants were assessed for life stress and symptoms of anxiety, depression, and PTSD.

Here’s what they found:

• Alpha diversity: Women with high levels of anxiety or depression had oral microbiomes with many types of microbe species present in relatively even amounts.
• Beta diversity: Women with severe PTSD symptoms had saliva microbiomes significantly different in composition from those with lower levels of PTSD.
• Specific mental health traits were linked to the presence of certain microbe species in saliva.

These findings suggest that the oral microbiome may offer clues to understanding the biological mechanisms of mental health struggles during pregnancy.

The researchers propose that targeting the oral microbiome could pave the way for new interventions. This might include probiotic treatments, dietary changes, or even tailored oral health recommendations to improve maternal mental health.

“Successful targeting of the gut microbiome with probiotic treatment to improve maternal mental health could be extended in future studies to target oral cavity microbes,” the research team suggests.

While gut health and its link to mental health have been widely studied, this research highlights a lesser-known area: the mouth.

Pregnancy can be a time of immense joy but also stress and emotional challenges. Studies like this underscore the importance of mental health during pregnancy, not just for mothers but also for their babies.

While the idea of “treating stress through spit” may still be in its early stages, the findings offer hope for new ways to support mums who are struggling. As this field of research grows, it could lead to accessible and non-invasive treatments that make a real difference during pregnancy.

This fascinating link between saliva and mental health is another reminder of how interconnected our bodies are—and how even small insights could lead to big breakthroughs in maternal health care.

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