Microbiota and pregnancy

This article reviews the pregnancy microbiota literature published between April 2019 and March 2020. The literature this past year has been far reaching including research into pathological pregnancy outcomes, predominately; preeclampsia (PE), gestational diabetes mellitus (GDM) and preterm birth (PTB). Other conditions covered included preterm pre-labour rupture of membranes, bacterial vaginosis, miscarriage, fetal growth, allergies in the offspring, psychiatric disorders, and pregnancy after bariatric surgery. Of 94 identified papers, 21 were review papers and 19 papers were of mechanistic animal studies in mice, rats, cows and various other animals, including an attempt at elucidating the presence of a placental microbiome in animals and placental/endometrial microbiota in humans. Three human interventional trials were published, two probiotic interventions for vaginal microbiota alteration and one investigating whether antimicrobial toothpaste can change the oral microbiota. These were published along with two protocols for randomised control trials (RCT). Most papers focused on the bacterial component of the gut microbiota through 16S ribosomal RNA (rRNA) gene sequencing of the V4 hypervariable region. Three studies included metagenomic and multi-omic analysis, and 24 included vaginal, oral or blood microbiota analysis.