P786 Mode of delivery and risk of inflammatory bowel disease

Abstract

Background: Recent evidence suggests that early life exposures known to influence microbiome development (eg, breastfeeding, exposure to antibiotics, etc.) may also affect the risk of developing IBD. Mode of delivery is one of the major factors impacting the newborn's microbiome development, and specifically, Caesarean-section (C-section), which has been associated with altered colonisation of commensal gut flora, is thought to predispose to immune-mediated diseases later in life. The relation between C-section and IBD is not yet well characterised with different studies showing conflicting results. Therefore, we performed a meta-analysis to evaluate the risk of IBD, Crohn's disease (CD) and ulcerative colitis (UC) according to mode of delivery (C-section vs. vaginal delivery). Methods: A systematic search was performed in PubMed and Scopus. Case-control and cohort studies were included. The primary outcome was the risk of IBD in individuals delivered vaginally compared with those born by C-section. Secondary outcomes were UC and CD risk according to mode of delivery and IBD risk in individuals born by emergent compared with elective C-section. Heterogeneity between the studies was assessed. Publication bias was evaluated by funnel plots and Egger's test. Study's quality was characterised using the Newcastle Ottawa Scale (NOS). Analysis was conducted using Comprehensive Meta-Analysis v2. Results: 11 studies fulfilled the inclusion criteria, of which 6 were population-based. All the studies were from developed countries (UK, Denmark, Australia, USA, Germany, Canada, Scotland, Norway, Sweden) and 5 were limited to paediatric age. No publication bias was detected. Overall, the total number of IBD patients was 15,292 that were compared with 6,981,080 controls. When looking at all studies together, C-section was not associated with a higher risk of IBD (OR 1.02 [95% CI 0.84-1.24], p = 0.86). We observed a trend towards an increased risk for CD in individuals born by C-section compared with those vaginally delivered, without significant results (OR 1.39 [95% CI 0.99-1.71], p = 0.06). No association was found between C-section and UC (OR 0.99 [95% CI 0.76-1.30], p = 0.94). No differences were found in IBD risk when comparing elective and emergent C-section (OR 1.05, [95% CI 0.59-1.87], p = 0.87). Conclusions: Overall, the risk of developing IBD was not affected by mode of delivery. Likewise, the setting of C-section (emergent vs. elective) did not affect IBD risk. Individuals born by C-section may have a higher risk for CD.