# The Stool Volatile Metabolome of Pre-Term Babies
## 2 Results
### Metabolomic Profile of Stool Samples from Pre-Term Babies
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Compound** & \multicolumn{2}{c}{**Postnatal Age (Days)**} & \multicolumn{2}{c}{**Gestational Age (Weeks)**} & \multicolumn{2}{c}{**Delivery Mode**} \\ \hline  & **Slope** & \(p\)**-Value** & **Parameter** & \(p\)**-Value** & **Parameter** & \(p\)**-Value** \\ \hline \multicolumn{5}{c}{**Short chain fatty acids**} \\ Butanoic acid & 0.28 & *** & \(-\) & \(-\) & \(-\) & \(-\) \\ Acetic acid & 0.08 & * & \(-\) & \(-\) & \(-\) & \(-\) \\ Propionic acid & 0.15 & * & \(-\) & \(-\) & \(-\) & \(-\) \\ \hline \multicolumn{5}{c}{**Branched chain fatty acids**} \\ Isovaleric acid & 0.2 & ** & \(-\) & \(-\) & \(-\) & \(-\) \\
2-methylbutanoic acid & 0.24 & *** & \(-\) & \(-\) & \(-\) & \(-\) \\ \hline \multicolumn{5}{c}{**Esters**} \\ Ethyl acetate & 0.19 & ** & 0.87 & * & \(-\)4.07 & * \\ Propyl acetate & 0.36 & *** & 1.15 & * & \(-\) & \(-\) \\ Ethyl propionate & 0.27 & *** & 0.88 & * & \(-\) & \(-\) \\ Propyl propionate & 0.36 & *** & 1.02 & * & \(-\) & \(-\) \\ \hline \multicolumn{5}{c}{**Aldehydes**} \\ Heptanal & 0.11 & * & \(-\) & \(-\) & \(-\) & \(-\) \\ Octanal & 0.13 & * & \(-\) & \(-\) & 3.17 & * \\ Nonanal & 0.14 & ** & \(-\) & \(-\) & \(-\) & \(-\) \\ Benzaldehyde & 0.15 & ** & \(-\) & \(-\) & \(-\) & \(-\) \\ Phenylacetaldehyde & 0.2 & *** & \(-\) & \(-\) & \(-\) & \(-\) \\ \hline \multicolumn{5}{c}{**Alcohals**} \\ Propanol & 0.38 & *** & \(-\) & \(-\) & \(-\) & \(-\) \\
1-decen-3-ol & \(-\) & \(-\) & \(-\)0.76 & * & 3.45 & ** \\ \hline \multicolumn{5}{c}{**Ketones/diketones**} \\
2-heptanone & \(-\) & \(-\) & \(-\) & \(-\) & 3.95 & ** \\
4-heptanone & \(-\) & \(-\) & \(-\)\(-\).38 & *** & \(-\) & \(-\) \\
6-methyl-5-hepten-2-one & 0.18 & *** & \(-\) & \(-\) & \(-\) & \(-\) \\ Acetoin & 0.18 & ** & \(-\) & \(-\) & \(-\) & \(-\) \\
2,3-butanedione & 0.27 & *** & \(-\) & \(-\) & \(-\) & \(-\) \\ \hline \multicolumn{5}{c}{**Others**} \\
2-ethylfuran & \(-\) & \(-\) & \(-\) & \(-\) & 2.66 & * \\
2-pentylfuran & \(-\) & \(-\) & \(-\) & \(-\) & 4.11 & ** \\ Methoxy-phenyl-oxime & 0.15 & ** & \(-\) & \(-\) & \(-\) & \(-\) \\ \hline \hline \end{tabular} A positive slope for infant age (days) indicates an increase in the compound over time; a positive value for gestational age indicates that babies born later had none of that compound; a positive value for delivery mode means that babies born through a caesarean section had more of that compound, opposite to a negative slope that refers to a compound being more prevalent in babies born by vaginal delivery. Values that were not significant are not shown (\(-\)). Significance codes: \(-p\) not significant, *\(p\) \(<\) 0.05, **\(p\) \(<\)0.01, **\(p\) \(<\) 0.001. All samples were included, n = 152.  
\end{table} 
Table 4: List of volatile organic compounds (VOCs) that were influenced by relevant variables obtained with linear mixed-effects (LME) analysis. Figure 3: Boxplots for a selection of compounds (abundance/gestational age and delivery mode). Each boxplot represents a compound, and these are grouped according to the variable of interest (gestational age and delivery mode). All samples were included, n = 152.