Maternal gut microbiota displays minor changes in overweight and obese women with GDM.

BACKGROUND AND AIMS: Previous literature have shown a diversity of findings regarding the relationship between the maternal gut microbiota and gestational diabetes mellitus (GDM). We investigated the gut microbiota of overweight and obese women with gestational diabetes mellitus (GDM) against matched euglycaemic women at 16 and 28-weeks' gestation. METHODS AND RESULTS: This study included women from the SPRING (Study of PRobiotics IN Gestational diabetes) cohort. Overweight and obese women with no impaired glucose tolerance or impaired fasted glucose were enrolled prior to gestational age <16 weeks. Participants with a diagnosis of GDM (n = 29) were matched with euglycaemic (n = 29) women for body mass index, probiotic or placebo intervention, maternal age, parity and ethnicity. Anthropometric, clinical and fecal microbiota (16S rRNA amplicon-based sequencing of V6-V8 region) data was assessed at 16 and 28-weeks' gestation. The relative abundances of key bacterial genera were not significantly altered between euglycaemic women and women with GDM. Occurrence of bacterial taxa was similar between groups at both timepoints. GDM was associated with decreased Shannon diversity (p = 0.02) without differentiated clustering measured by beta diversity at 28-weeks' gestation. CONCLUSIONS: Overweight and obese women with GDM demonstrate minor variation in the gut microbiota at 16 and 28-weeks' gestation compared with matched euglycaemic women. This study expands on previous literature concluding the microbiota does not likely have a disease-specific characterisation in GDM.