Pasvol TJ, Bloom S, Segal AW, et al. - Increasing duration of exposure to combined oral contraceptive pills (COCPs) was associated with an increase in the risk of inflammatory bowel disease (IBD). The results of this study are broadly consistent with a hypothesis that the oestrogen component of contraception may drive IBD pathogenesis.

• In this nested case–control study, women aged 15-49 years with a new diagnosis of IBD were matched with up to six controls by age, practice and year (4,932 incident cases of IBD matched to 29,340 controls).

• An association was found between use of COCPs and development of Crohn's disease and ulcerative colitis (odds ratios OR: 1.60 and 1.30, respectively).

• The observed risk of Crohn's disease and that of ulcerative colitis increased by 6.4% (5.1%-7.7%) and 3.3% (2.1%-4.4%), respectively, in relation to each additional month of COCP exposure per year of follow-up.

• There was no impact of progestogen-only pills on Crohn's disease risk (OR 1.09) but these pills were modestly related to ulcerative colitis (OR 1.35).

• No link was found between parenteral progestogen-only contraception and IBD.