Study design for longitudinal examination of nutritional exposures on preterm infant microbiome. Infants grouped by one of three feeding groups: mothers breast milk (MBM), pasteurized human donor milk (PDMH), and infant formula (IF). Samples analyzed on days indicated with an “X”. Feeding code for each day as follows: gray = NPO, red = MBM, blue = PDHM, yellow = IF. Days when a combination of feeding types were fed indicated in purple (MBM/PDHM), orange (MBM/IF), green (PDHM/IF), or brown (MBM, PDHM, IF). Birth delivery mode indicated by cesarean section (CS) or vaginal (V). Maternal antibiotics during labor and birth indicated by yes (Y). (PDF 2210 kb)