The maternal microbiome in normal pregnancy and at delivery by cesarean section and the early developmental phase of the neonatal microbiome—presentation of a longitudinal pilot study

Aim

In this study by Foessleitner et al., both the maternal microbiome in the third trimester of pregnancy and the factors that influence the development of the child’s microbiome after cesarean delivery were investigated.

Methods

Maternal vaginal and rectal swabs were collected at inclusion in the last trimester of pregnancy and on the day of the cesarean section. In addition, placental and intrauterine swabs as well as infant dermal, buccal, and meconium swabs were taken during the cesarean section immediately after birth and subsequently on the second/third day of life. All samples were analyzed for microbial composition using 16s rRNA amplicon sequencing.

Results

A total of 30 mothers and their newborns were included in the study, with microbiome samples available for all maternal, intrauterine cavity, and placenta samples, as well as for 18 out of the 30 newborns. The vaginal and rectal microbiome was stable over the course of the third trimester and showed no significant changes (permutational multivariate analysis of variance [PERMANOVA]; p > 0.05). Both the intraoperative samples (placental, intrauterine) and the neonatal swabs at the time of birth were consistently sterile. However, rapid infant microbial colonization subsequently occurred, with neonatal buccal mucosa and stool samples showing significantly different microbial colonization from their mothers as early as the second/third day of life (PERMANOVA; p < 0.01).

Conclusion

The conclusion of the presented study was therefore that the vaginal and rectal microbiome of healthy pregnant women does not change in the last trimester, the infant and the placenta are not microbially colonized at the time of birth, and the development of the newborn’s microbiome after birth appears to be influenced mainly by environmental exposure.