Maternal obesity is associated with gut microbial metabolic potential in offspring during infancy

Children born to obese mothers are at increased risk for obesity, but the mechanisms behind this association are not fully understood. Our study aimed to investigate differences in the functions encoded by the microbiome of infants at 18 months of age when the transition from early infant-feeding to solid family foods is established. To investigate the impact of maternal prepregnancy body mass index on infants' gut microbiome, faecal samples from infants born to normoweight (n = 21) and obese mothers (n = 18) were analysed by 16S rRNA gene sequencing and a functional-inference-based microbiome analysis. Our results indicated that Firmicutes was significantly enriched in infants born to normoweight mothers whereas Bacteroidetes was significantly enriched in infants born to obese women. In both microbiomes, the greatest number of genes (>50%) that were assigned a function encoded for proteins involved in "metabolism" among tier 1 KEGG Orthology (KO) categories. At lower KO functional categories, the microbiome of infants born to normoweight mothers was characterized by a significant enrichment in the abundances of "pentose phosphate pathway" (p = 0.037), "lysine biosynthesis" (p = 0.043), "glycerolipid metabolism" (p = 0.042), and "C5-branched dibasic acid metabolism" (p = 0.045). Notably, the microbiome of infants born to obese mothers was significantly enriched in "streptomycin biosynthesis" (p = 0.047), "sulphur metabolism" (p = 0.041), "taurine and hypotaurine metabolism" (p = 0.036), and "lipopolysaccharide biosynthesis" (p = 0.043). In summary, our study showed that maternal prepregnancy obesity may imprint a selective gut microbial composition during late infancy with distinct functional performances.