Maternal diet in pregnancy and the risk of inflammatory bowel disease in the offspring: a prospective cohort study

Background: Diet has been hypothesized as a risk factor for development of inflammatory bowel disease (IBD).

Objective: To explore associations between maternal diet diversity and quality in pregnancy and the offspring's risk of IBD.

Methods: We used data from a nationwide cohort study on 85,129 Norwegian children followed from birth (1999-2009) with information on maternal diet in pregnancy from validated food frequency questionnaires. Hazard ratios (aHRs) for IBD, Crohn's disease (CD), and ulcerative colitis (UC) by maternal diet diversity, quality and intake amounts of individual food groups were adjusted for maternal body mass index, parental IBD, and socio-demographic factors. Sensitivity analyses adjusted for the child's early-life diet quality and antibiotic treatment. Dietary exposures were classified into tertiles, comparing low (reference) to medium, and high levels.

Results: During a mean follow-up time of 16.1 years (1,367,837 person-years of follow-up), 268 children developed IBD (CD, n=119; UC, n=76; IBD-unclassified, n=73). High compared with low diet diversity in pregnancy was associated with a lower risk of UC in the offspring (aHR 0.46, 95% confidence interval 0.25-0.87), with consistent findings after further adjustment for the child's early-life diet quality and antibiotic treatment. High compared with low diet diversity in pregnancy yielded aHRs of 0.81 for CD (0.51-1.28) and 0.75 for any IBD (0.55-1.02) in the offspring. A high compared with low diet quality in pregnancy or intakes of specific food groups were not associated with the offspring's risk of IBD or its subtypes.

Conclusions: Our findings suggest that a higher maternal diet diversity in pregnancy may be associated with a lower risk of UC in the offspring.