We studied the clinical courses of 70 pregnancies in 47 women with ulcerative colitis (UC) and 18 pregnancies in 12 women with Crohn's disease (CD) retrospectively. We concluded as follows. 1. Pregnancy has less influence on the course of UC. 2. The patients with UC who kept remission for more than 1 year before conception have less risk of relapse and severity during pregnancy. 3. The patients with active UC at the time of conception tend to worsen during pregnancy. The patients whose onset of UC is during pregnancy tend to worsen. 4. UC has a little influence on the course of pregnancy except severe active disease. 5. It is not obtained that pregnancy becomes a relapsing factor of CD. 6. CD during pregnancy has little influences on the course of pregnancy, if it is remitted. 7. Salazosulfapyridine and corticosteroids therapy has less influence on the fetus and the course of pregnancy.