Species composition of vaginal lactobacilli in the first, second and third trimester as a marker of pregnancy outcomes

Abstract

BACKGROUND: Lactobacilli are the main and most important component of the vaginal microbiota of reproductive-age women. During pregnancy, the composition of the vaginal microbiota changes and acquires additional significance, acting as a barrier against infection for both the mother and the fetus. Furthermore, the vaginal microbiota contributes to the normal course of pregnancy, postpartum recovery, and primary colonization of the newborn. Changes in the composition and number of vaginal lactobacilli during pregnancy can lead to serious disorders. Despite much research on the role of the vaginal microbiota, the details of how changes in lactobacilli composition and diversity may affect pregnancy outcomes are poorly understood. AIM: The aim of this study was to evaluate the vaginal lactoflora composition and stability in each trimester to predict pregnancy outcomes. MATERIALS AND METHODS: This open prospective study involved 100 women who had been registered at the dispensary in early pregnancy (up to 12 weeks). To determine the type of microbiocenosis and the species composition of lactobacilli, the vaginal discharge was examined microscopically and by real-time polymerase chain reaction. RESULTS: Normocenosis was identified in 86 (86%) pregnant women, the intermediate type of vaginal microbiocenosis in 4 (4%) pregnant women, and bacterial vaginosis in 10 (10%) pregnant women. The rate of negative pregnancy outcomes was 19%, of which 7% and 12% of women had premature births or miscarriages, respectively. The concentration of vaginal lactobacilli in each pregnant woman was relatively stable over the three trimesters. Among the dominant microflora, the frequency of Lactobacillus crispatus increased by the third trimester. Lactobacillus iners was associated with an increased incidence of premature birth and may be considered as a risk factor. CONCLUSIONS: Real-time PCR test for specific detection and quantification of vaginal lactobacilli in pregnant women has prognostic value and may be recommended as a possible screening test for women with high risk of adverse pregnancy outcomes.