New Insights into Vaginal Environment During Pregnancy

Area of Science:

• Reproductive biology and microbiology
• Maternal-fetal medicine
• Biochemistry and metabolomics

Background:

• The vaginal ecosystem undergoes significant transformations during pregnancy, characterized by increased Lactobacillus spp. and altered metabolic profiles.
• Understanding these changes is crucial for pregnancy physiology and identifying risks for complications like preterm birth and miscarriage.

Purpose of the Study:

• To characterize the vaginal ecosystem in normal pregnancy and spontaneous miscarriage.
• To identify potential biomarkers for early pregnancy loss and understand pregnancy-related vaginal changes.

Main Methods:

• Assessed vaginal bacterial composition (Nugent score) and metabolic profiles (1H-NMR spectroscopy) in pregnant women and those with miscarriage.
• Measured vaginal levels of cytokines (IL-6, IL-8) and correlated findings with clinical data.

Main Results:

• Vaginal microbiota became less diverse and dominated by lactobacilli during pregnancy, associated with reduced dysbiosis metabolites and increased healthy metabolites like lactate and glycine.
• Lower glucose levels indicated a normal vaginal environment. IL-6 and IL-8 levels correlated with leukocytes and symptoms, not dysbiosis, but IL-8 predicted Candida presence.
• Spontaneous abortions were linked to abnormal vaginal microbiomes and specific metabolite elevations, without increased pro-inflammatory cytokines.

Conclusions:

• Pregnancy-specific vaginal microbiome and metabolome shifts occur, with distinct profiles associated with normal pregnancy versus miscarriage.
• Metabolite alterations, rather than pro-inflammatory cytokines, appear more indicative of miscarriage risk.
• The study identifies potential novel biomarkers for early pregnancy loss diagnosis.