Risk of Inflammatory Bowel Disease According to Self-Rated Health, Pregnancy Course, and Pregnancy Complications: A Study within the Danish National Birth Cohort

Background: Poor self-rated health (SRH) has been connected to immunological changes, and pregnancy complications have been suggested in the etiology of autoimmune diseases including inflammatory bowel disease (IBD). We evaluated the impact of self-rated pre-pregnancy health and pregnancy course, hyperemesis, gestational hypertension, and preeclampsia on risk of IBD. Methods: Information was collected by questionnaires from The Danish National Birth Cohort (enrolment 1996-2002) at 16th and 30th week of pregnancy and 6 months postpartum. A total of 55,699 women were followed from childbirth until development of IBD (using validated National Hospital Discharge Register diagnoses), emigration, death, or end of follow-up, 31st of October, 2011. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated using Cox proportional hazards models adjusting for age and evaluating pre-pregnancy BMI, parity, alcohol and tobacco consumption, and socio-occupational status as potential confounders. Results: Risk of IBD increased with decreasing level of self-rated pre-pregnancy health (p = 0.002) and was elevated in women with poor self-rated pregnancy course (HR, 1.61, 95% CI 1.22-2.12). Associations persisted for more than 5 years postpartum. Hyperemesis and preeclampsia were not significantly associated with risk of IBD. Conclusions: This is the first prospective observational study to suggest that poor self-rated health - in general and in relation to pregnancy - is associated with increased risk of IBD even in the long term though results needs further confirmation. Symptoms of specific pregnancy complications were, on the other hand, not significantly associated with risk of IBD.