Genomic composition of the vaginal microbiota in the first trimester and pregnancy outcomes

• Olga V. Budilovskaya
• Natalia R. Beliaeva
• Tatiana A. Husnutdinova
• Kira V. Shalepo
• Anna A. Krysanova
• Natalya I. Tapilskaya
• Alevtina M. Savicheva
• Igor Yu. Kogan

Abstract

The role of the vaginal microbiota during pregnancy acquires additional importance, acting as an anti-infective barrier for both mother and fetus. The change in the composition of the vaginal microbiota begins already from the first weeks of pregnancy. However, to date, the details of how changes in the composition and diversity of the vaginal microflora can affect pregnancy outcomes have not been sufficiently studied.

The aim of the study was to determine the genomic composition of the vaginal microbiota in the first trimester of pregnancy and to track pregnancy outcomes in different types of microbiocenosis.

Material and methods. 123 pregnant women who were registered in a women’s clinic for up to 12 weeks were examined. According to the outcome of pregnancy, all women were divided into 3 groups: group 1 – women who gave birth on time (n=91); group 2 – women who had premature birth (n=13); group 3 – women whose pregnancy was terminated before 22 weeks (n=19). At registration, a vaginal discharge was obtained in all pregnant women for microscopic and molecular biological assessment of microbiocenosis.

Results. The study of the genomic composition of the vaginal microbiota in the first trimester of pregnancy showed the presence of lactobacilli in all samples with the predominance of L. iners and L. crispatus species, while the L. iners species was more often found in pregnant women who gave birth prematurely. The dominance of the L. crispatus species was noted much more often in women who gave birth on time. Bacterial vaginosis was diagnosed in 11% of pregnant women, was asymptomatic and in no case was associated with premature birth. The detection of any conditionally pathogenic microorganisms, including mycoplasmas or ureaplasmas in early pregnancy, was also not associated with adverse pregnancy outcomes.

Conclusion. The dominance of lactobacilli, especially the L. crispatus species, is a favorable prognostic criterion for pregnancy, since it suppresses the diversity of the vaginal microbiota, reduces the risk of colonization by facultative and obligate anaerobes and potential pathogens, and also reduces the corresponding risk of premature birth.

Keywords: vaginal microbiota; vaginal lactobacilli; pregnancy outcomes; emergency delivery; premature birth; miscarriages

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