Investigating prenatal and perinatal factors on meconium microbiota: a systematic review and cohort study

Abstract

Background The first-pass meconium has been suggested as a proxy for the fetal gut microbiota because it is formed in utero. This systematic review and cohort study investigated how pre- and perinatal factors influence the composition of the meconium microbiota. Methods We performed the systematic review using Covidence by searching PubMed, Scopus, and Web of Science databases with the search terms “meconium microbiome” and “meconium microbiota”. In the cohort study, we performed 16 S rRNA gene sequencing on 393 meconium samples and analyzed the sequencing data using QIIME2. Results Our systematic review identified 69 studies exploring prenatal factors, immediate perinatal factors, and microbial composition in relation to subsequent health of infants but gave only limited comparative evidence regarding factors related to the composition of the meconium microbiota. The cohort study pointed to a low-biomass microbiota consisting of the phyla Firmicutes, Proteobacteria and Actinobacteriota and the genera Staphylococcus, Escherichia-Shigella and Lactobacillus, and indicated that immediate perinatal factors affected the composition of the meconium microbiota more than did prenatal factors. Conclusions This finding supports the idea that the meconium microbiota mostly starts developing during delivery. Impact It is unclear when the first-pass meconium microbiota develops, and what are the sources of the colonization. In this systematic review, we found 69 studies exploring prenatal factors, immediate perinatal factors, and microbial composition relative to subsequent health of infants, but there was no consensus on the factors affecting the meconium microbiota development. In this cohort study, immediate perinatal factors markedly affected the meconium microbiota development while prenatal factors had little effect on it. As the meconium microbiota composition was influenced by immediate perinatal factors, the present study supports the idea that the initial gut microbiota develops mainly during delivery.

Comparison of gut microbiomes between neonates born by cesarean section and vaginal delivery: prospective observational study

“…The limitation of our study was the potential confounding effect of breastfeeding practices on a neonate's gut microbiome. Thus, collection of the first passing of meconium may represent an opportunity to access the neonatal gut microbiome directly after delivery (34) . Second, we have not stated the details of cesarean delivery, such as presenting with membrane rupture before cesarean delivery.…”

Winds of change a tale of: asthma and microbiome

“…They orally inoculated pregnant mice and successfully recovered the microorganism from the meconium and amniotic fluid of the cesarean-born animals ( Jiménez et al, 2008 ). However, a systematic review reports that the meconium microbiota in humans begins to develop after birth ( Turunen et al, 2023 ).…”

From Mother to Infant, from Placenta to Gut: Understanding Varied Microbiome Profiles in Neonates

“…This paradigm held validity because attempts were made to culture bacteria that were largely non-culturable. However, with the advent of molecular techniques, particularly those based on 16S rRNA, microorganisms have been identified in both meconium and amniotic fluid [26]. High-throughput meconial microbial sequencing has revealed a substantially distinct microbial taxonomy compared to that which could be attributed to potential cross-contamination from the anus or uterus.…”