Selected Vaginal Bacteria and Risk of Preterm Birth: An Ecological Perspective

Abstract

We examined the community ecology of vaginal microbial samples taken from pregnant women with previous preterm birth experience to investigate whether targeted pathogenic and commensal bacteria are related to risk of preterm birth in the current pregnancy. We found a significant correlation between the community structure of selected bacteria and birth outcome, but the correlation differed among self-reported racial/ethnic groups. Using a community ordination analysis, we observed infrequent co-occurrence of Mycoplasma and bacteria vaginosis associated bacteria 3 (BVAB3) among black and Hispanic participants. In addition, we found that the vaginal bacteria responded differently in different racial/ethnic groups to modifications of maternal behavioral (ie, douching and smoking) and biological traits (ie, body mass index [BMI]). Even after accounting for these maternal behaviors and traits, the selected vaginal bacteria was significantly associated with preterm birth among black and Hispanic participants. By contrast, white participants did not exhibit significant correlation between microbial community and birth outcome. Findings from this study affirm the necessity of considering women's race/ethnicity when evaluating the correlation between vaginal bacteria and preterm birth. The study also illustrates the importance of studying the vaginal microbiota from an ecological perspective, and demonstrates the power of ecological community analysis to improve understanding of infectious disease.

Epidemiologic Factors and Urogenital Infections Associated With Preterm Birth in a Midwestern U.S. Population

“…In contrast, a recent Brussels study (28) of nearly 2000 pregnancies found Ureaplasma species to be a significant risk for preterm birth, and a commensurate risk of preterm birth was associated with abnormal flora, but only if Ureaplasma species was culture positive. These variable results may be related to differences in vaginal ecologies as recently described in studies of high-risk pregnancies (29,30). …”

Vaginal microbiome profiles of pregnant women in Korea using a 16S metagenomics approach

“…Romero et al detected no difference in the microbial profiles of women who subsequently delivered term or preterm, whereas others reported differences in the prevalence and abundance of organisms such as Leptotrichia / Sneathia (bacteria associated with vaginosis), Mobiluncus spp., and Mycoplasma spp. in the vaginal microbiomes of women who delivered preterm . However, no comparative study has characterized the vaginal microbiome of pregnant women in Korea.…”

Mycoplasma, bacterial vaginosis–associated bacteria BVAB3, race, and risk of preterm birth in a high-risk cohort

“…Total bacterial load was estimated using a broad coverage universal bacterial primer for the 16S rrn gene. Primer sequences and conditions used for individual taxa were reported previously 13 . The limit of detection was 100 copies and readings lower than the limit were considered negative.…”