Gut microbiome differences after vaginal birth in relation to rupture of membranes at term: a prospective longitudinal cohort study of twins

The purpose of this study is to investigate the impact of intrapartum events, such as rupture of membranes and vaginal examinations, on the infant gut microbiome in twins born vaginally. This prospective longitudinal cohort study included pregnant women with twin pregnancies beyond 36 weeks of gestation undergoing vaginal births. Stool samples were collected from newborns on days 4 and 28 for gut microbiome analysis using 16S rDNA sequencing. The infants were followed for at least 1 year. Forty babies were followed in this study. Gestational age at birth was 37.07 (36.75-37.57) weeks. Significant differences were observed between the first and second twins in the number of vaginal examinations (5.50 (4.00-7.25) vs. 1.00 (1.00-1.00), P < 0.001) and the rupture of membranes to birth time (524 (324-734.5) vs. 7.5 (4.5-9.0) minutes, P < 0.001). Bifidobacterium spp. were present in all samples, with differing relative abundance profiles on day 4 and day 28. On day 4, the first twins had over 50% Bifidobacterium spp., while second twins had less than 25%. By day 28, 75% of samples showed similar Bifidobacterium spp. profiles. Microbiome changes over time were more significant in second twins. At the species level, 20-40% of samples exhibited significant Bifidobacterium longum on day 4, higher in first twins compared to second twins.

Differences in the microbiome and its evolution between first and second twins were noted within the first 4 and 28 days of life, influenced by membrane rupture duration and the number of vaginal examinations for the first twin.

•Differences in the gut microbiome have been shown between infants born via cesarean and vaginal birth. •Colonization by maternal microbiota at birth is influenced by multiple perinatal factors.

•Between twins born vaginally, the gut microbiome differs based on the duration of membrane rupture and the number of vaginal examinations. •This difference is noticeable on day 4 of life but ceases to be noticeable by day 28.