Abstract
Vaginal dysbiosis has been identified to be associated with adverse pregnancy outcomes, such as preterm delivery and premature rupture of membranes. However, the overall structure and composition of vaginal microbiota in different trimesters of the pregnant women has not been fully elucidated. In this study, the physiological changes of the vaginal microbiota in healthy pregnant women were investigated. A total of 83 healthy pregnant participants were enrolled, who are in the first, second, or third pregnancy trimester. Quantitative real-time PCR was used to explore the abundant bacteria in the vaginal microbiota. No significant difference in the abundance of Gardnerella, Atopobium, Megasphaera, Eggerthella, Leptotrichia/Sneathia, or Prevotella was found among different trimesters, except Lactobacillus. Compared with the first pregnancy trimester, the abundance of L. iners decreased in the second and third trimester while the abundance of L. crispatus was increased in the second trimester. Moreover, we also found that vaginal cleanliness is correlated with the present of Lactobacillus, Atopobium, and Prevotella and leukocyte esterase is associated with Lactobacillus, Atopobium, Gardnerella, Eggerthella, Leptotrichia/Sneathia, and Prevotella. For those whose vaginal cleanliness raised or leukocyte esterase became positive, the richness of L. iners increased, while that of L. crispatus decreased significantly. Our present data indicated that the altered vaginal microbiota, mainly Lactobacillus, could be observed among different trimesters of pregnancy and L. iners could be considered as a potential bacterial marker for evaluating vaginal cleanliness and leukocyte esterase.
Highlights
Vaginal dysbiosis has been identified to be associated with adverse pregnancy outcomes, such as preterm delivery and premature rupture of membranes
Bacterial vaginosis (BV) is a condition in which the vaginal microbiota suffer a reduction in several species of probiotic Lactobacillus and an increase in the presence of anaerobes (Gardnerella vaginalis, Atopobium vaginae, and Mobiluncus sp.), which has been shown in our previous studies [18, 19]
Vaginal samples of 83 healthy pregnant women were analyzed. e varying gestational ages of the women screened were compared in terms of clinical characteristics, laboratory characteristics, and the presence of leukocyte esterase (Table 2). ere was no difference in the maternal ages, gravidity, or parity among the three trimester groups, indicating that the participants in each of the different groups had similar clinical characteristics and were comparable throughout this study
Summary
Vaginal dysbiosis has been identified to be associated with adverse pregnancy outcomes, such as preterm delivery and premature rupture of membranes. We found that vaginal cleanliness is correlated with the present of Lactobacillus, Atopobium, and Prevotella and leukocyte esterase is associated with Lactobacillus, Atopobium, Gardnerella, Eggerthella, Leptotrichia/Sneathia, and Prevotella For those whose vaginal cleanliness raised or leukocyte esterase became positive, the richness of L. iners increased, while that of L. crispatus decreased significantly. Healthy pregnancy is characterized by a temporary dynamic shift towards stable, reduced richness and low diversity in the community structures dominated by Lactobacillus spp. which aids in the prevention of pathogenic bacteria, different from the vaginal microbiota composition of nonpregnant women [16, 17]. It is hypothesized that colonization of the pathogenic bacteria in the vagina activates the local and upper (cervical and fetal membrane) innate immune system, drives an inflammatory cascade, and leads to a remodeling and disruption of membrane architecture and preterm delivery or PROM [20, 21]
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