Objectives: To examine the association between early-life smoking exposure and later risk of inflammatory bowel disease [IBD]. Methods: We followed 115663 participants from the Norwegian Mother, Father and Child [MoBa] and All Babies in Southeast Sweden [ABIS] cohorts from birth [1997–2009] through 2021. IBD was identified through national patient registers. Validated questionnaire data defined maternal smoking during pregnancy, maternal environmental tobacco smoke [ETS] exposure during pregnancy, and child ETS exposure by ages 12 and 36 months. Cox regression was used to estimate adjusted hazard ratios [aHRs] for sex, maternal age, education level, parental IBD, and origin. Cohort-specific estimates were pooled using a random-effects model. Results: During 1 987 430 person-years of follow-up, 444 participants developed IBD [ABIS, 112; MoBa, 332]. Any vs no maternal smoking during pregnancy yielded a pooled aHR of 1.30 [95% CI = 0.97–1.74] for offspring IBD. Higher level of maternal smoking during pregnancy (compared with no smoking, average ≥6 cigarettes/day: pooled aHR = 1.60 [95% CI = 1.08–2.38]) was associated with offspring IBD, whereas a lower smoking level was not (average 1–5 cigarettes/day: pooled aHR = 1.09 [95% CI = 0.73–1.64]). Child ETS exposure in the first year of life was associated with later IBD (any vs no ETS, pooled aHR = 1.32 [95% CI = 1.03–1.69]). Estimates observed for child ETS exposure by 36 months were similar but not statistically significant. Conclusions: In this prospective Scandinavian cohort study, children exposed to higher levels of maternal smoking during pregnancy or ETS during the first year of life were at increased risk of later IBD.

Background and Objective: Retrospective data have linked adult physical activity (PA) to reduced risk of inflammatory bowel disease (IBD). We aimed to prospectively examine the association of PA and screen time (ST) in childhood with later risk of IBD, for which data are scarce.Methods: Using two population‐based birth cohorts (All Babies in Southeast Sweden [ABIS] and Norwegian Mother, Father, and Child Cohort Study [MoBa]), we retrieved parent‐reported data on PA and ST degree at ages 3 and 8 years. Data were modelled as binary (high vs. low) and numerical (hours/day) exposures. Inflammatory bowel disease was defined as ≥2 diagnostic records in national health registers. Cox regression estimated hazard ratios adjusted for potential confounding from parental IBD, country of origin, education, and smoking habits (Adjusted hazard ratio (aHR)). Our 8‐year analyses included a 2‐year lag period to reduce the risk of reverse causation. Cohort‐specific estimates were pooled using random‐effects model.Result: Among 65,978 participants from ABIS (n = 8810) and MoBa (n = 57,168) with available data, 266 developed IBD. At 3 years, children with high versus low PA had an aHR of 1.12 for IBD (95%CI = 0.87–1.43); high versus low ST showed an aHR of 0.91 (95%CI = 0.71–1.17). Conversely, at 8 years, high versus low ST was associated with increased risk of later IBD (aHR = 1.51; 95%CI = 1.02–2.25), but PA at 8 years, was not linked to IBD (aHR = 1.19; 95%CI = 0.80–1.76). Subtype‐specific analyses for Crohn's disease and ulcerative colitis did not differ appreciably.Conclusion: Acknowledging possible confounding variables, children with high versus low ST at 8 years were at increased risk of IBD. In contrast, PA degree was not linked to IBD at any age category.

Background: Ecological observations suggest a negative relationship between childhood socioeconomic status (SES) and inflammatory bowel disease (IBD) risk. Individual-level analyses have been inconsistent and mostly lacked refined assessments of SES. We aimed to comprehensively study the association between early-life SES and later IBD. Methods: This study included 117 493 participants from the Norwegian Mother, Father and Child cohort and Swedish All Babies in Southeast Sweden cohorts. Participants were followed from birth (1997-2009) through 2021. IBD was identified through national patient registers. Questionnaire and register data were used to define parental educational level, employment, and household income level. Cox regression estimated adjusted hazard ratios (aHRs), accounting for other SES exposures and covariates (eg, parental IBD). Cohort-specific estimates were pooled using a random-effects model. Results: During 2 024 299 person-years of follow-up, 451 participants were diagnosed with IBD (All Babies in Southeast Sweden cohort, n = 113 and Norwegian Mother, Father and Child cohort, n = 338). Early-life maternal, but not paternal, educational level was associated with later IBD (low vs high educational level; pooled aHR, 1.81; 95% confidence interval [CI], 1.16-2.82; and pooled aHR, 1.20; 95% CI, 0.80-1.80; respectively). Having a nonworking mother or father was not significantly associated with IBD (pooled aHR, 0.69; 95% CI, 0.47-1.02; pooled aHR, 0.79; 95% CI, 0.45-1.37). High vs low household income level yielded a pooled aHR of 1.33 (95% CI, 0.94-1.89). Overall, results were largely consistent across cohorts. Conclusions: In this prospective Scandinavian cohort study, low maternal educational level was, independent of other SES and covariates, significantly associated with later IBD in her child. Further research is needed to elucidate factors that may mediate this relationship.

Background: Patients undergoing pelvic radiotherapy are often advised to omit fiber-rich foods from their diet to reduce the adverse effects of treatment. Scientific evidence supporting this recommendation is lacking, and recent studies on animals and humans have suggested that there is a beneficial effect of dietary fiber for the alleviation of symptoms. Randomized controlled studies on dietary fiber intake during pelvic radiotherapy of sufficient size and duration are needed. As preparation for such a large-scale study, we evaluated the feasibility, compliance, participation rate, and logistics and report our findings here in this preparatory study.Methods: In this preparatory study of a fiber intervention trial, Swedish gynecological cancer patients scheduled for radiotherapy were recruited between January 2019 and August 2020. During the intervention, the participants filled out questionnaires and used an application. They also consumed a fiber supplement at first in powder form, later in capsules. Blood- and fecal samples were collected. The study is registered in clinicaltrials.gov (https://clinicaltrials.gov/ct2/show/NCT04534075?cond=fidura&draw=2&rank=1).Results: Among 136 approached patients, 57 started the study and the participation rate for primary outcomes was 63% (third blood sample) and 65% (third questionnaire). Barely half of the participants provided fecal samples. Providing concise and relevant information to the patients at the right time was crucial in getting them to participate and stay in the study. The most common reasons for declining participation or dropping out were the expected burden of radiotherapy or acute side effects. Tailoring the ambition level to each patient concerning the collection of data beyond the primary endpoints was an important strategy to keep the dropout rate at an acceptable level. Using capsules rather than psyllium in powder form made it much easier to document intake and to create a control group. During the course of the preparatory study, we improved the logistics and for the last 12 participants included, the participation rate was 100% for the earliest primary outcome.Conclusion: A variety of adjustments in this preparatory study resulted in an improved participation rate, which allowed us to set a final protocol and proceed with the main study.

We have developed a mobile phone application for measuring the intake of dietary fiber and validated the ability of the application to accurately capture this intake against measurements registered by a dietary record. We also investigated what food groups contributed most to the total, soluble, and insoluble dietary fiber intake. Twenty-six randomly selected Swedish women aged 35–85 years were included and randomized to either start to register dietary intake in the application or by a dietary record, during three consecutive days. After a washout period of at least two weeks, the participants used the other method. We found that the difference in measured mean fiber intake between the dietary record and the application was two grams independent of the total intake per day. A statistically significant correlation between fiber intake as measured by the two methods was found (rho = 0.65, p < 0.001). Vegetables and roots were the predominantly contributing foods to total and soluble fiber intake. Bread and crackers contributed most to insoluble fiber intake. In conclusion, the application may be considered as a useful and easy-to-use method to measure dietary fiber intake.

Background: Complementary feeding (ie, food introduction besides formula or breast milk) imprints on the developing gut microbiome and immune system, which may have durable influences on disease risk. This study aimed to prospectively assess the association between the timing of complementary feeding and subsequent inflammatory bowel disease (IBD) risk. Methods: We followed 94 238 participants from the All Babies in Southeast Sweden (ABIS) (n = 11 947) and the Norwegian Mother, Father and Child (MoBa) (n = 82 291) cohorts from birth (1997-2009) through 2023 (mean age 16.5 [MoBa] to 25.2 [ABIS] years). National patient registers identified IBD diagnoses. The timing of complementary food introduction (<4, 4-5, or ≥6 months) was assessed using early-life food diaries and questionnaires. Latent class analyses identified 4 patterns across introductions of major food groups (eg, cereals and dairy). Cox regression estimated hazard ratios (aHRs) for IBD adjusted for socio-demographics and parental IBD. Sensitivity analysis additionally adjusted for breastfeeding duration, formula feeding, and perinatal factors. Results: Over 1 562 350 person-years of follow-up, 400 participants developed IBD (ABIS, n = 124; MoBa, n = 276). Overall timing of complementary food introduction was not associated with IBD (<4 months: aHR, 1.04 [95% CI, 0.67-1.60]; 4-5 months: aHR, 0.83 [95% CI, 0.63-1.10] vs ≥6 months). Also, aHRs for IBD by latent class analyses–defined introduction patterns approached 1. Results were consistent across cohorts, sensitivity analyses, and Crohn’s disease and ulcerative colitis subtypes. Conclusions: The findings from this binational birth cohort study indicate that neither the timing nor the pattern of complementary food introduction is a major risk factor for later development of IBD.