Bifidobacteria is a key marker of a healthy gut flora in infants. A Brazilian study of 49 newborns — 24 full-term and 25 pre-term (31.2 weeks) — explored the prevalence and concentration of bifidobacteria in stools of one-month-old newborns using qPCR.
Bifidobacterium genus and B. longum species were present in all stool samples at one month of age. Counts were higher in full-term (8.3 log cells/g) than in pre-term (7.1), and prevalence of other species were different. Counts of B. longum species were also higher after vaginal (8.5) than after caesarean (6.9) delivery in full-term newborns.
The authors concluded that gestational age might influence bacterial numbers and species in a broad way, while mode of delivery might impact bifidobacteria specifically. They suggest that specific probiotics may compensate for the lower amount of bifidobacteria in some newborns.