Breastfeeding factors and gut microbiota dynamics in infants during the first year: a Beijing cohort study

To clarify the impact of maternal nutrition and breastfeeding on infant gut microbiota development.

In a cohort of 67 mother-infant dyads, maternal diet and milk composition were analyzed alongside longitudinal infant fecal 16S rRNA profiling at 42 days, 6 months, and 12 months.

The infant gut microbiota underwent marked shifts over the first year, with increases in Firmicutes and Bacteroidota, decreases in Actinobacteriota and Proteobacteria, and increasing alpha diversity. Feeding mode was the strongest predictor of infant gut microbiota. Feeding mode, delivery mode, maternal dietary deficiency, complementary feeding timing, and breast-milk density were each associated with distinct microbial taxa, with 14 genus-/phylum-level associations identified.

Significant phylum-level shifts occurred over the first year, specifically increases in Firmicutes and Bacteroidota. Feeding mode was the dominant predictor of microbiota composition at 12 months, with additional associations for delivery mode, complementary feeding timing, maternal dietary deficiency, and breast-milk density.