Data for: Major gut microbiota perturbations in firstborn infants compared to those with older siblings soon after delivery

The dataset includes variables on: Host factors and early life exposures: sex, delivery mode (caesarian section or vaginal), older siblings (yes or no), exposure to antibiotics during delivery (intrapartum antibiotics, yes or no) and breastfeeding. Gut microbiota development: presence and population counts of selected bacterial groups at 9 timepoints between 3 days and 18 months of age.

These data were obtained using quantitative bacterial culture of fecal samples, targeting key facultative and anaerobic bacteria of the infant gut (exception: samples obtained at 3 days of age were not cultured quantitatively and targeted facultative bacteria only).