Impact of Postpartum Hospital Length-of-Stay on Infant Gut Microbiota: A Comprehensive Analysis of Vaginal and Caesarean birth

Background: The primary concern with prolonged hospitalization following birth is the risk of acquiring hospital-acquired infections (HAIs) caused by opportunistic bacteria, which can alter the early establishment of gut microbiota.

Objective: This study aimed to assess the association between postpartum hospital length-of-stay (LOS) and the composition of gut microbiota at 3 and 12 months of age according to birth mode.

Methods: A total of 1313 Canadian infants from the CHILD Cohort Study were involved in this study. Prolonged hospital LOS was defined as > 2 days following vaginal and > 3 days after caesarean section (CS) birth. Infants' gut microbiota was characterized by Illumina 16S rRNA sequencing of faecal samples at 3-4 months and 12 months.

Findings: Following a prolonged hospital LOS, vaginally-delivered (VD) infants with no maternal intrapartum antibiotic (IAP) exposure had a higher abundance of bacteria in their gut known to cause HAIs, including Enterococcus at 3 and 12 months, Citrobacter at 3 months and C. difficile at 12 months. Enterococcus or Citrobacter abundance at 3 months significantly mediated the association between LOS, and low abundance of Bacteroidaceae, or higher Enterococcaeae/Bacteriodaceae or Enterobacteriaceae/Bacteroidaceae abundance ratios at 12 months of age in VD infants without IAP exposure. HAI-causing Enterobacteriaceae were also more abundant in later infancy with a longer hospital LOS following CS. In the absence of exclusive breastfeeding for 3 months or any breastfeeding at 12 months, the Porphyromonadaceae (of Bacteroidota) become depleted in CS infants with a prolonged LOS.

Conclusions: Prolonged hospital stay after birth is associated with infant gut dysbiosis.