1. Oral contraceptive use and smoking are risk factors for relapse in Crohn's disease 
Antje Timmer*, Lloyd R. Sutherland*,‡, Francois Martin§ 
Gastroenterology 
Volume 114, Issue 6, Pages (June 1998)
DOI: /S (98)
Copyright © 1998 American Gastroenterological Association Terms and Conditions

2. Fig. 1 Kaplan–Meier survival curves for relapse by smoking status.
Gastroenterology  , DOI: ( /S (98) )
Copyright © 1998 American Gastroenterological Association Terms and Conditions

3. Fig. 2 Kaplan–Meier survival curves for relapse by OC use.
Gastroenterology  , DOI: ( /S (98) )
Copyright © 1998 American Gastroenterological Association Terms and Conditions

4. Fig. 3 Combined effect of smoking and use of OCs.
Gastroenterology  , DOI: ( /S (98) )
Copyright © 1998 American Gastroenterological Association Terms and Conditions