Vaginal microbiota in term pregnant women with differences in cervical ripeness revealed by 2bRAD-M

Cervical ripening is a multifactorial outcome, and the association between cervical ripening and vaginal microbiota remains unexplored in term primiparous women. A new sequencing technology, microbiome 2bRAD sequencing (2bRAD-M) that provides a higher level of species discrimination compared to amplicon sequencing. We applied 2bRAD-M to analyze the vaginal microbiota in a population with variations in cervical ripeness and to explore potential microbiota factors influencing cervical ripening.

A total of 30 full-term primigravid women participated in this study, with 15 belonging to the low scoring group of cervical ripeness and 15 to the high scoring group. Clinical information was collected from the participants, and the vaginal microbiota and community structure of both groups were analyzed using 2bRAD-M sequencing. Microbiota diversity and differential analyses were conducted to explore potential factors influencing cervical ripening.

A total of 605 species were detected. There was no difference in vaginal microbiota diversity between the two groups, and the vaginal microbial composition was structurally similar. In the two groups, Lactobacillus crispatus and Lactobacillus iners were identified as the two pivotal species through random forest analysis. Concurrent, extensive and close connections between species within the two groups were observed in the correlation analysis, influencing the aforementioned two species. Pairwise comparisons showed that Sphingomonas (P = 0.0017) and three others were abundant in high scoring group, while Alloprevotella (P = 0.0014), Tannerella (P = 0.0033), Bacteroides (P = 0.0132), Malassezia (P = 0.0296), Catonella (P = 0.0353) and Pseudomonas (P = 0.0353) and so on showed higher abundance in low scoring group. Linear discriminant analysis effect size identified 29 discriminative feature taxa.

For the first time, vaginal microbiota was sequenced using 2bRAD-M. With a relatively simple structure, a more stable vaginal microbiota is associated with higher cervical ripeness, and certain microorganisms, such as Sphingomonas, may play a beneficial role in cervical ripening.