Fig. 2

Differences in 16S rRNA gene microbial abundance in amniotic fluid samples from preterm deliveries and intact pregnancies. A Box plots show the gene copy numbers of 16S rRNA gene per mL of AF samples of intact pregnancy (red) and preterm delivery (blue) and prevailed a significantly higher bacterial load in AF samples of preterm deliveries. B Box plots of different alpha diversity indices show that richness and Shannon diversity was significantly reduced in AF samples of preterm deliveries while evenness did not differ. Statistical analysis was performed using Wilcoxon Rank-Sum test. C NMDS plot of weighted Unifrac distances shows significant (p < 0.05) altered bacterial 16S rRNA gene community composition for AF samples of preterm deliveries. Statistical analysis was performed using PERMANOVA with Benjamini–Hochberg correction for multiple comparisons. D Heat tree including genera ≥ 0.1% of all reads. The tree shows the taxonomic information (domain to genus) and represents a comparison between preterm AF samples and samples of intact pregnancies. Coloured taxa are more abundant (based on log2-transformed ratio of median proportions) in the samples indicated (red: increased in preterm, blue: increased in intact). Significant changes (p < 0.05 based on Wilcoxon-Rank-Sum test with FDR correction) are marked with asterisks