Both ulcerative colitis and Crohn's disease were more common among women currently using oral contraceptives than among those not doing so. Incidences per 1000 woman years for ulcerative colitis were 0.26 in users and 0.11 in non-users; for Crohn's disease the incidences were 0.13 and 0.07 respectively. Though the association between the use of oral contraceptives and chronic inflammatory bowel disease cannot be regarded as established, the effects of smoking have been shown consistently in many studies. This observation provides an important clue to the aetiology of chronic inflammatory bowel disease.
The above is from this link...
http://www.bmj.com/cgi/content/abstract/292/6528/1101
BCP can exacerbate IBD symptoms because of the bacterial imbalance from taking birth control pill which is why it's so important to be sure you're taking a good probiotic daily and indefinitely...but also with BCP it cause hormonal fluctuations that can also interfere with IBD (exacerbating symptoms in this way as well).
Check out this link too...
http://www.womens-health.co.uk/pill-ibd.html
BCP made my symptoms worse.
:)