Minor impact on fertility in men with inflammatory bowel disease : A National Cohort Study from Sweden

Background and Aims Onset of inflammatory bowel disease (IBD) in men is most common during childbearing age, but little is known about the impact on fertility. Previous studies of fertility in men were small, which justifies this large nation-based registry study. Methods Fertility was assessed in a national cohort of men with IBD aged 15-44 years in 1964-2014, identified from the Swedish National Patient Register, and in a reference cohort matched for age and place of residence (ratio 1:5). Information about childbirths was found in the Swedish Multi-Generation Register. Patients with indeterminate colitis or inconsistent IBD coding were classified as IBD-unclassified (IBD-U). Results The cohorts included 29,104 men with IBD and 140,901 matched individuals. IBD patients had a lower fertility rate (number of births per 1000 person years) compared with the matched individuals; 1.28 (SD 1.27) versus 1.35 (SD 1.31; p < 0.001). Fertility was somewhat impaired in all IBD subtypes compared with the matched cohort; ulcerative colitis (UC) (hazard ratio [HR] 0.93, 95% CI 0.91-0.96), Crohn's disease (CD) (HR 0.95, 95% CI 0.92-0.98) and IBD-U 0.92, 95% CI 0.89-0.95. The cumulated total parity and the parity progression were also decreased for all IBD subtypes. Within the IBD cohort disease severity, intensity of medical treatment (CD) and bowel surgery (IBD-U) were further associated with impaired fertility. Conclusions This nationwide cohort study shows only slightly impaired fertility in men with IBD