Prognostic significance of the microbial factor in patients with miscarriage in early pregnancy registration

Background: The role of the microbial factor in the genesis of early miscarriages (up to 10 weeks of pregnancy) has not been established. However, disruption of the vaginal microbiota may be associated with the occurrence of late miscarriage.

Aim: The aim of this study was to evaluate the frequency of early and late miscarriages and to determine the prognostic significance of the microbial factor in early pregnancy registration.

Materials and methods: This study involved 113 pregnant women registered before 10 weeks of gestation, who were divided into two study groups. Group I consisted of 22 women whose pregnancy ended in miscarriage before 22 weeks (subgroup IA of 19 patients with early miscarriage and subgroup IB of three patients with late miscarriage). Group II comprised 91 women whose pregnancy ended in term delivery. Vaginal microflora was investigated using microscopic and molecular biological methods.

Results: The frequency of miscarriages among the examined women was 20.4%. The proportion of early miscarriages was 86.4% and late miscarriages 13.6%. In Group I, the number of births in the anamnesis was higher than in Group II. The average rate of births per woman was 2.0 in Group I and 0.9 in Group II (p = 0.037); the number of previous pregnancy loss per woman was 1.2 in Group I and 0.5 in Group II (p = 0.019). Lactobacilli were detected in the vaginal biotope of all pregnant women. Lactobacillus iners and Lactobacillus crispatus were the most frequently occurring species. In subgroup IA and Group II, opportunistic pathogenic microorganisms were detected with equal frequency at first pregnancy examination and did not alter the existing vaginal microbiocenosis. In subgroup IB, Gardnerella vaginalis, Atopobium vaginae, Enterobacteriaceae, Staphylococcus spp., Streptococcus spp., Mycoplasma hominis or Ureaplasma spp. were detected simultaneously in early pregnancy, with Lactobacillus cristatus predominating.

Conclusions: The proportion of early miscarriages was six times higher than that of late miscarriages. We have not found an association between the quantitative and qualitative compositions of vaginal microorganisms in the first trimester of pregnancy and early miscarriages. The microbial factor was established to be important in late miscarriages. Further studies are needed to assess the prognosis of late miscarriages at the time of pregnancy registration.