A heatmap of the gut microbiota of the preterm children receiving placebo.
breast milk
The counts of the bacterial groups have been converted into relative abundances, then CLR-transformed for the samples, and Z-transformed for the features (taxa) so that the heatmap is distributed around 0. The The effect of possible confounding factors on the gut microbiota.The R2 values that describe to what extent the gestational age, delivery mode, and sex of the child explain the variance in different bacterial taxonomic levels in the gut microbiota. In brackets, the All children received their own mothers’ breastmilk. On average, they started to receive it at the age of 1.3 days. All but one child (in group M -LGG + Bb12) received additionally donor breast milk, commonly starting on the day they were born, except for one child who was given donor milk at the age of 3 days (in group C -LGG + Bb12). Five children received formula at discharge, but this happened after the faecal samples were obtained at the age of 7 days. These were subjects from groups C -LGG, Placebo (3 children), and C -LGG + Bb12. According to the hospital guideline, all children with birth weight below 1800 g received breast milk fortifier until their weight was ca. 3500 g.The children and their mothers received antibiotics if needed according to the hospital’s protocol, which are well in line with the current clinical practice. Consequently, only 3 of 68 children (in groups C -LGG, M -LGG, and Placebo) did not receive any antibiotics during the study. The children usually received benzylpenicillin with gentamicin. The mothers of 43 children received intrapartum antibiotics, the most common reason being prophylaxis (usually benzylpenicillin or cefuroxime with or without azithromycin) due to caesarean section. The number of the children whose mothers received intrapartum antibiotics in each group were: C -LGG: 7/13 children, M -LGG + Bb12: 8/10 children, M -LGG: 10/17 children, Placebo: 8/14 children, C -LGG + Bb12: 10/14 children.The choice of the probiotic strain and the route of administration had a definite effect on the children’s gut microbiota. The gut microbiota compositions of the children directly receiving the probiotic combination (LGG + Bb12), in particular, were significantly different from those of the children receiving the other intervention modes or placebo (