Fig. 1

Composition of gut microbiota at phylum level in all subjects studied during the three trimesters of pregnancy. Histogram of gut microbiota (GM) composition in each subject at phylum level during the first trimester (T1), the second trimester (T2) and the third trimester (T3) (A); Dynamic change in the abundance ratio of Bacteroidetes/Firmicutes (B/F) in each subject from T1 to T3 (B). There was an overall increasing trend in B/F value from T1 (red), T2 (green) to T3 (blue) in 19 women, and no increasing trend from T1 (yellow), T2 (green) to T3 (blue) in the rest 11 women