Early Establishment of Bifidobacterium-Dominant Microbiome in Planned Cesarean-Born Infants via Bifidobacterium breve strain Yakult Supplementation: A Randomized, Double-blind, Placebo-controlled, Parallel-group Pilot Study

AbstractObjectives To investigate the effects of Bifidobacterium breve strain Yakult (BbrY) administration immediately after birth on the microbiome of cesarean-born full-term infants with an immature microbiota at birth. Methods This single-center, placebo-controlled, randomized, double-blind, parallel-group intervention study included healthy, full-term Japanese infants born via planned cesarean section. Infants were administered either BbrY or placebo for the first month of life. The primary endpoint was the early establishment of a Bifidobacterium-dominant microbiome. Results This study included 26 infants (14 in the BbrY group and 12 in the placebo group). Compared with the placebo group, the BbrY group showed significantly increased detection rates and counts of BbrY from day three to six months post-birth, with the levels and proportion of Bifidobacterium and Bifidobacteriaceae remaining elevated until one month post-birth. Total bacterial counts and total organic acid concentrations, including acetic and lactic acids, were significantly higher in the BbrY group until the sixth day of life, concomitant with a decrease in fecal pH. At nine months, the BbrY group exhibited a significantly higher body weight than the placebo group, and the Kaup index remained within the normal range at six and nine months. Conclusions BbrY supplementation immediately after birth facilitated the early establishment of a Bifidobacterium-dominant microbiome and contributed to intestinal acidification in cesarean-born infants, indicating BbrY administration may support normal growth patterns during infancy.