This preliminary investigation from an ongoing birth cohort study examined associations between objectively measured physical activity (PA) via Fitbit Charge and gut microbiota composition in 68 pregnant women. Stool samples were collected in the third trimester. The primary outcome was gut microbiota composition, assessed by alpha diversity (richness, Pielou's evenness, Faith's phylogenetic diversity) and beta diversity (unweighted and weighted UniFrac, Canberra, Bray-Curtis).
None of the PA variables during the second or third trimester were associated with alpha diversity metrics. However, the proportion of sedentary time during the second trimester was significantly associated with stool microbiota composition (R2 = 0.038, p = 0.035 for weighted UniFrac). Similarly, sedentary time in the third trimester was associated (R2 = 0.025, p = 0.034 for Bray-Curtis), as was the proportion of time 'fairly' or 'very active' during the third trimester (R2 = 0.025, p = 0.047 for Bray-Curtis).
Women with higher sedentary time in the second and third trimesters had significantly lower abundances of Prevotella and Pasteurellaceae ASVs and higher abundances of Acidaminococcus and Finegoldia (pFDR < 0.05). Two specific ASVs (ASV_84 [Acidaminococcus intestine] and ASV_134 [Oscillospirales sp.]) were positively associated with sedentary behavior. No significant microbial changes were observed with time spent 'fairly' or 'very active' during the third trimester.
Safety and tolerability were not reported. Key limitations include the preliminary nature of the investigation and the small sample size from an ongoing cohort. The findings are associative and do not establish causation. Clinicians should interpret these results cautiously, as they are based on surrogate outcomes and require replication.
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BackgroundThis study investigated the relationship between objectively measured physical activity (PA) and gut microbiota composition during pregnancy.MethodsIn an ongoing birth cohort study, the Fitbit Charge wearable activity monitor was used to objectively measure PA during pregnancy. To profile the composition of gut bacterial microbiota, 16S rRNA sequencing was performed on a third trimester stool sample. Differences in alpha diversity metrics (richness, Pielou’s evenness, and Faith’s phylogenetic diversity) by PA were determined using linear regression, whereas beta diversity (unweighted and weighted UniFrac, Canberra, and Bray-Curtis) relationships were assessed using permutational multivariate analysis of variance (PERMANOVA). Differential abundance testing at both the amplicon sequence variants and genus level was conducted using Analysis of Compositions of Microbiomes with Bias Correction 2; tests were corrected for false discovery rate (FDR) and considered significant if pFDR < 0.05.ResultsThe analytic sample included 68 pregnant women with both PA and 16S rRNA sequencing data (median age [quartile 1; quartile 3] = 30.7 [26.6; 33.3] years; 56% Black). Women typically took around 5000 steps per day (second trimester median = 5486; third trimester median = 5074) and the majority of activity minutes were classified as sedentary (second trimester median = 77%; third trimester median = 78%). None of the PA variables during the second or third trimester were associated with gut microbiota richness, evenness, or diversity. After covariate adjustment, the proportion sedentary during the second (Weighted UniFrac p = 0.035, R2 = 0.038) and third (Bray-Curtis p = 0.034, R2 = 0.025) trimesters were significantly associated with stool microbiota composition. Additionally, the proportion “fairly” or “very active” during the third trimester was significantly associated with stool microbiota composition (PERMANOVA; Bray-Curtis p = 0.047, R2 = 0.025). These compositional differences were partly characterized by significantly lower abundances of Prevotella and Pasteurellaceae ASVs and higher abundances of Acidaminococcus and Finegoldia in pregnant women with higher second and third trimester sedentary time (pFDR < 0.05). Two specific 16S rRNA sequence variants (ASV_84 [Acidaminococcus intestine] and ASV_134 [Oscillospirales sp.]) were also positively associated with sedentary behavior. No significant microbial changes were observed with the proportion of time spent “fairly” or “very active” during the third trimester.ConclusionsThese findings highlight sedentary behavior as a potential modifiable factor related with maternal gut microbiota composition during pregnancy. This study forms the basis for future studies on the impact of sedentary time on gut microbiota during pregnancy.
