Figure 3 |. Microbe-metabolite correlations and metabolic models suggest sources for sPTB-associated metabolites.

a, A network of microbial correlations with metabolites associated with sPTB. Ellipses, microbial species; blue and red diamonds, metabolites enriched in TB and sPTB, respectively; blue and red edges, negative and positive Spearman correlations with FDR<0.1, |ρ| > 0.25, respectively; edge width, median ρ. See Extended Data Fig. 6a for the same network without grouped nodes. b,c, Box and swarm plots (line, median; box, IQR; whiskers, 1.5*IQR) of tyramine levels, as measured (b) and predicted with metabolic models (Methods; c), comparing preterm and term deliveries and stratifying by maternal self-identified race. White women who delivered preterm had lower measured vaginal levels of tyramine (p=0.0002), yet our metabolic models predict higher, albeit non-statistically significant, microbiome production of tyramine in women who delivered preterm (p=0.18 and p=0.26 for all and White women, respectively). p, Two-sided Mann-Whitney U. d, Tyramine production derived from microbiome metabolic models (NMPC; Methods; y-axis) plotted against measured tyramine levels (x-axis) and colored by race and birth outcome (legend). While our models are generally accurate for tyramine (Spearman ρ=0.62, p<10⁻¹⁰ across all women), the accuracy for White women who delivered preterm was significantly lower (Spearman ρ=0.19, p=0.02 for comparing correlation strength vs the correlation in other women, two-sided Fisher R-to-z transform), suggesting a difference in strains, functional capacity, or a non-microbial interaction not captured by our models.