To determine the safety of corticosteroids and sulfasalazine in pregnancy associated with inflammatory bowel disease, we reviewed the outcome of 531 such pregnancies in a national survey. Two hundred eighty-seven pregnancies (172 ulcerative colitis and 115 Crohn's disease) were treated with either or both drugs, whereas 244 (137 ulcerative colitis and 107 Crohn's disease) received neither. The frequency of fetal complications was significantly lower in both "treated" and "untreated" groups, as compared with the reported rates in the general pregnant population. We conclude: 1. Inflammatory bowel disease, except for severe active Crohn's disease, does not seem to affect the outcome of concurrent pregnancy adversely. 2. The use of corticosteroid and sulfasalazine in pregnancy associated with ulcerative colitis is unlikely to increase the fetal morbidity or mortality. 3. Patients with severe Crohn's disease requiring corticosteroid and/or both drugs experience more complications than the "untreated" ones, but still fewer than the prevailing rates in the general pregnant population. The higher complication rate seems to be associated more with disease-related factors than the use of these drugs. 4. In the management of inflammatory bowel disease associated with pregnancy, either or both drugs may be used just as in the nonpregnant patients.