Crohn's disease and pregnancy. Seventy-eight pregnancies in 50 patients were reviewed to evaluate the effects of Crohn's disease on the outcome of pregnancy and the influence of the pregnancy on the course of Crohn's disease. Overall, 21 pregnancies (27 percent) had abnormal outcomes including spontaneous abortions (9), infants small for gestational age (6), premature infants (5), and infants who developed respiratory distress (1). Eight (50 percent) patients with active disease compared with 13 (21 percent) patients with inactive disease at conception had abnormal outcomes (P less than 0.05). During pregnancy 15 (55 percent) with active disease and 6 (12 percent) with inactive disease had an abnormal outcome (P less than 0.001). Neither medical nor surgical treatment, independent of disease activity, appeared to affect the outcome adversely. Eighteen of 73 (25 percent) patients with quiescent or mild disease relapsed, and seven of 16 patients with some disease activity improved (44 percent). Of 34 patients on medication, nine relapsed (27 percent), and of 39 patients not on medication, nine relapsed (24 percent) (P = N.S.). These results suggest that the outcome of pregnancy is not adversely affected by Crohn's disease. However, patients with active disease at conception and/or during the pregnancy have poorer outcomes independent of the use of medication or requirement of surgery. Neither pregnancy nor medications taken affect the course of the disease. 