Metagenomic characterization of the maternal prenatal gastrointestinal microbiome by pregravid BMI.

Abstract

The incidence of women entering into pregnancy with BMI indicating overweight or obesity is rising with concurrent increases in adverse complications such as gestational diabetes. Although several studies have examined the compositional changes to the microbiome across BMI classifications, there has been no investigation regarding changes in microbial function during pregnancy. A total of 105 gastrointestinal microbiome biospecimens were used in this analysis. Biospecimens were sequenced by using the Illumina NovaSeq 6000 shotgun metagenomics platform. Findings indicate an enrichment in microbiota from the phylum Firmicutes across all pregravid BMI groups with a decrease in α diversity in groups with BMI indicating obesity or overweight compared with a group with BMI indicating normal weight (p = 0.02). More specifically, women with BMI indicating obesity or overweight had enrichment in Bifidobacterium bifidum and B. adolescentis. Women with BMI > 25 kg/m² had a higher abundance of microbiota that support biotin synthesis and regulate epithelial cells in the lower gastrointestinal tract. These epithelial cells are responsible for host adaptability to dietary lipid variation and caloric absorption. Our analysis suggests that there are differences in microbial composition and function between BMI groups. Future research should consider how these changes contribute to specific clinical outcomes during pregnancy.