Background: Research has revealed associations between microbes of the gastrointestinal tract and stress, anxiety and depression in pregnant or postpartum women. While these studies suggest a gut-brain-behaviour axis, no studies have examined microbes of the oral cavity in relation to maternal mental health.
Objective: To explore a potential oral-brain-behaviour axis related to maternal mental health.
Methods: Microbes were measured in saliva obtained from 224 second-trimester (mean±SD = 17±2 weeks) women oversampled for stress. Oralome data were associated with women's recent or cumulative pregnancy stress, trait and state anxiety, depression symptoms and post-traumatic stress disorder (PTSD) symptoms. Covariates explored included age, income, alcohol and tobacco use, dental issues and physical health problems.
Results: Pregnant women in the high trait anxiety or depression symptom groups had higher oral alpha diversity, indicating higher richness of species within samples. Groups with high and low PTSD symptoms differed in beta diversity, reflecting differences in community composition. Linear discriminant analysis showed differently abundant microbes in women with high stress versus low life stress, anxiety, depression, and PTSD, with the affected microbes mostly differing by symptom. Notably, members of phylum Proteobacteria were more abundant in women with high recent life stress and Spirochaetes was more abundant in women with high depression symptoms. Members of phylum Firmicutes were more abundant in the high trait anxiety and high depression groups. Genus Dialister (previously found to be lower in the gut of depressed non-pregnant people) was higher in women experiencing either high trait or state anxiety, or experiencing high depression symptoms, while genus Eikenella was elevated with high trait anxiety, depression or PTSD.
Conclusions: The oral microbiome is associated with stress and mental health in pregnant women, in ways different from the gut microbiome or what has been found in non-pregnant people.
Clinical implications: Understanding oral microbiome-mental health relations may reveal future microbial targets to improve maternal psychological well-being.
Keywords: Adult psychiatry; Anxiety disorders; Depression.
© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. Published by BMJ.