Ethnic Background and Vaginal Microbiota

Written by
Fathalla Ali, Bsc MSc, MPH and PHD student UNSW

The vaginal microbiota is complex ecosystem influenced by ethnic background, genes, and environmental and behavioural factors. The healthy vagina is dominated by several Lactobacillus species that support the defence system against infection and dysbiosis (an imbalance in the microbial community that is associated with disease). The acidic metabolites of these species maintain the low pH and impair the colonization by aerobic and anaerobic acid sensitive bacteria. Consequently, maintaining low microbiota diversity in the vagina. High microbiota diversity in the vagina found to be associated with increased risk of bacterial infection known as bacterial vaginosis.

According to recent study published in Nature Medicine, Serrano et al. examined the vaginal microbiome of women in cross-sectional sampled cohort of 1,969 non-pregnant and 613 pregnant women of African, Hispanic or European ancestry and a longitudinal sampled cohort of 90 pregnant women of African and non-African ancestry.

  • In this study, the vaginal microbiota of pregnant women shifted toward Lactobacillus-dominated environment at the expense of microbiota associated with vaginal dysbiosis.
  • Additionally, the bacterial diversity in pregnant women was lower than of non-pregnant women.
  • Samples collected longitudinally across the pregnancy found that, the diversity of vaginal microbiota of African ancestry women was higher than that of non-African ancestry women, but the conversion toward Lactobacillus-dominated microbiota accompanied by a significant decrease in the diversity achieved as pregnancy progress in African ancestry women.
  • The prevalence of Lactobacillus-dominated microbiota in women of African ancestry was lower in the first than the later trimester, whereas women of non-African ancestry had higher prevalence Lactobacillus-dominated microbiota throughout pregnancy.
  • Therefore, this study provides evidence that gestational changes transform vaginal microbiota toward a bacterial community that promote anti-inflammatory and resistance to infection resulted in decrease disease risk and maximize health.

Keywords: Microbiota, Vaginal microbiota, ethnicity and microbiota, non-pregnant women, pregnant women


Serrano, M. G., Parikh, H. I., Brooks, J. P., Edwards, D. J., Arodz, T. J., Edupuganti, L., Huang, B., Girerd, P. H., Bokhari, Y. A., Bradley, S. P., Brooks, J. L., Dickinson, M. R., Drake, J. I., Duckworth, R. A., 3rd, Fong, S. S., Glascock, A. L., Jean, S., Jimenez, N. R., Khoury, J., Koparde, V. N., … Buck, G. A. (2019). Racioethnic diversity in the dynamics of the vaginal microbiome during pregnancy. Nature medicine, 25(6), 1001–1011. Click here