Colonic Crohn's disease and use of oral contraception.

The prevalence of use of oral contraception before the onset of disease was established in 100 consecutive women attending follow up clinics for inflammatory bowel disease. A significant excess of women with Crohn's disease confined to the colon had taken oral contraceptives in the year before developing symptoms (10/16 (63%] compared with women with small-intestinal Crohn's disease (12/49 (24%); p less than 0.02) and women with ulcerative colitis (3/35 (9%); p less than 0.0005). When the patient groups were matched for age and year of onset of disease usage of oral contraception before the onset of disease was still more common among women with isolated colonic Crohn's disease (9/12, 75%) than among those with ulcerative colitis (2/12 (17%); p less than 0.02) and was also more common than would be expected from reported figures for oral contraception in England and Wales (31.4% of women aged under 41; p less than 0.005). A survey of current patient records showed that isolated colonic disease was at least twice as common among women with Crohn's disease (63/218, 29%) compared with men (25/181, 14%; p less than 0.001). These data support the suggestion made previously that oral contraceptives may predispose to a colitis that resembles colonic Crohn's disease.