Prematurity, delivery method and infant feeding type are not associated with paediatric-onset inflammatory bowel disease risk: A Scottish retrospective birth cohort study

Background and Aims:
The incidence of paediatric-onset inflammatory bowel disease (PIBD) continues to rise globally. We aimed to determine whether mode of delivery, gestational age at birth, or type of infant feeding contribute to the development of PIBD in a nationwide cohort of Scottish children.
Methods:
All children born in Scotland between 1981-2017 were identified using linked health administrative data to determine mode of delivery, gestational age at birth, and type of infant feeding. PIBD cases were defined as onset of Crohn’s disease (CD), ulcerative colitis (UC) or IBD-unclassified (IBDU) before age 16 years. Validation was performed within an entire Scottish health board (16% of total population) via individual case-note verification. Hazard ratios (HR) were calculated for each exposure using Cox proportional hazards models.
Results:
A study population of 2,013,851 children was identified including 1,721 PIBD cases. Validation of 261 PIBD patients coded as CD and/or UC identified 242 (93%) as true positive. Children delivered vaginally did not have an altered risk of developing PIBD compared to those delivered by caesarean section; adjusted HR 0.95 [95% CI 0.84-1.08] (p=0.46). Compared to children born at term (≥37 weeks), children born prematurely did not have an altered risk of developing PIBD; 24-31 weeks gestation HR 0.99 [95% CI 0.57-1.71] (p=0.97); 32-36 weeks gestation HR 0.96 (95% CI 0.76-1.20] (p=0.71). Compared to children exclusively breast fed at age 6 weeks, children exclusively formula fed did not have an altered risk of developing PIBD; adjusted HR 0.97 [95% CI 0.81-1.15] (p=0.69).
Conclusions:
This population-based study demonstrates no association between mode of delivery, gestational age, or exclusive formula feeding at 6 weeks and the development of PIBD.