Abstract: Objective To study the effect of umbilical vein catheterization on intestinal flora of very low birth weight infants. Methods A total of 41very low birth weight infants hospitalized in NICU from June 2019 to June2020 were enrolled. According to the umbilical vein catheterization status, they were divided into umbilical vein catheterization group (n=24) and nonumbilical vein catheterization group (n=17). Fecal samples were collected on day 1, 3 and 7 after birth. In order to study the effect of umbilical vein catheterization on intestinal flora, the diversity and relative abundance of intestinal flora between two groups at different times, Illumina high-throughput sequencing technology was used to sequence 16S gene. Results The detection rate of intestinal flora at the first day was low, so we did not compare the difference between the two groups. At the third day, there was no significant difference between the two groups in the Shannon index and relative abundance of all bacteria (P>0.05). At the seventh day, the Shannon index in umbilical vein catheterization group was significantly lower than that of non-umbilical vein catheterization group (P

Key words: umbilical vein catheterization; very low birth weight infants; intestinal flora