Ecological succession in the vaginal microbiota during pregnancy and birthOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study traced how the vaginal microbiota develops across the second half of pregnancy and birth, and how much it seeds the newborn. Vaginal samples were taken at pregnancy weeks 24 and 36 and at birth after rupture of membranes. Infant fecal and airway samples were collected one week after birth. All samples underwent 16S rRNA gene amplicon sequencing of the V4 region, with diversity, ordination and mother-to-child transfer analyses.
Who was studied?
The cohort was 57 women from the Danish COPSAC2010 mother-child birth cohort, sampled at pregnancy week 24 (n = 56), week 36 (n = 57), and at birth (n = 57). Samples were also collected from their singleton children one week after birth, from feces (n = 48) and airways (n = 39). Transfer analyses were restricted to the 49 vaginally delivered children, with 36 matching fecal and 45 matching airway samples available.
What were the most important findings?
Vaginal samples were dominated by Lactobacillus, which declined steadily from week 24 to birth. Its decline opened space for typical fecal, airway and skin taxa, raising diversity toward delivery. Faith's phylogenetic diversity rose between week 36 (median 5.90) and birth (8.59, p < 0.001). Each mother carried a strong individual signature, explaining about 60 percent of community variation. Vertical transfer was modest and spread across taxa rather than specific ones. The strongest transfer signals were for Clostridiales, then Lactobacillales and Enterobacteriales.
What are the greatest implications of this study?
The results show the perinatal vaginal microbiota develops gradually, not abruptly at labor, becoming more diverse and more like the neonatal gut and airways by birth. However, birth vaginal bacteria only modestly predicted the one-week infant microbiota. This suggests the newborn draws microbes from sources beyond the vagina, such as the maternal gut. The authors note they lacked maternal gut samples. They caution that species-level metagenomics is needed to map true mother-to-child transfer.