@Stewart_Barker here, very happy to be running the 50th meeting of the #MicroTwJC!

I will be tweeting from @MicroTwJC on the night (10th June, 8pm GMT), please remember to use #MicroTwJC on all tweets!

I stuck with the paper’s original title (I mean how can you re-word that?!), which can be found here: http://www.plosone.org/article/fetchObject.action?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0098514&representation=PDF

Although some may flinch at the term ‘vaginal microbiome’, it is an important area of cross-interdisciplinary study that has implications for infections during pregnancy. This study looks at n=12 caucasian women, and compares to a ‘complementary study’ on african-american women.

The usual questions apply!:

  1. Is the paper easy to understand?
  2. Are the methods used suitable and correct?
  3. Is the data well presented and analysed?
  4. Does the paper achieve what the authors set out to do?
  5. What further work can be carried out?



Objective: To assess the vaginal microbiome throughout full-term uncomplicated pregnancy.

Methods: Vaginal swabs were obtained from twelve pregnant women at 8-week intervals throughout their uncomplicated
pregnancies. Patients with symptoms of vaginal infection or with recent antibiotic use were excluded. Swabs were obtained
from the posterior fornix and cervix at 8–12, 17–21, 27–31, and 36–38 weeks of gestation. The microbial community was
profiled using hypervariable tag sequencing of the V3–V5 region of the 16S rRNA gene, producing approximately 8 million
reads on the Illumina MiSeq.

Results: Samples were dominated by a single genus, Lactobacillus, and exhibited low species diversity. For a majority of the
patients (n = 8), the vaginal microbiome was dominated by Lactobacillus crispatus throughout pregnancy. Two patients
showed Lactobacillus iners dominance during the course of pregnancy, and two showed a shift between the first and
second trimester from L. crispatus to L. iners dominance. In all of the samples only these two species were identified, and
were found at an abundance of higher than 1% in this study. Comparative analyses also showed that the vaginal
microbiome during pregnancy is characterized by a marked dominance of Lactobacillus species in both Caucasian and
African-American subjects. In addition, our Caucasian subject population clustered by trimester and progressed towards a
common attractor while African-American women clustered by subject instead and did not progress towards a common

Conclusion: Our analyses indicate normal pregnancy is characterized by a microbiome that has low diversity and high
stability. While Lactobacillus species strongly dominate the vaginal environment during pregnancy across the two studied
ethnicities, observed differences between the longitudinal dynamics of the analyzed populations may contribute to
divergent risk for pregnancy complications. This helps establish a baseline for investigating the role of the microbiome in
complications of pregnancy such as preterm labor and preterm delivery