This article reviews the pregnancy microbiota literature published between April 2020 and March 2021. The literature spans exploration of the microbiota during healthy pregnancies, and those with complications such as Gestational Diabetes Mellitus (GDM), preeclampsia (PE) and pre-term birth (PTB). Additionally, oral and vaginal microbial health, hypothyroidism, fertility and pregnancy loss were also studied. The predominant sequencing methodology used was 16S rRNA with only one human study using shotgun metagenomic sequencing. In addition to traditional microbiome papers defining the microbiome, microbial metabolites were also studied and included within this review.

Of the 70 identified papers, 41 articles contained original research: 25 observational human studies, 16 animal gestational mechanistic, associative studies in mice, rats and one porcine study. Twenty-nine review articles were also published during this period and are not included in this review.

The major findings within the past year support the notions of gut, oral and vaginal microbial stability during pregnancy. Variations in the microbiome being associated with different pregnancy complications, including species level stool microbiota differences in women with and without gestational diabetes, which may in future have value for monitoring of gestational diabetes. The presence of individual-specific microbial signatures preserved throughout the pregnancy has also been noted and the focus of the field has shifted to the functional aspects of the microbiome, its metabolites and their function.