Over a 13-year period, the course of 109 pregnancies in 68 women with Crohn's disease was studied. A total of 76 children were delivered. There were no gemellary deliveries, and none of the children had congenital malformations. Pregnancy entailed no increased risk of an exacerbation of the bowel disease. As compared with the reference population and with women with ulcerative colitis, the total material showed an increased risk of premature delivery and spontaneous abortion, but a further analysis showed that this was due only to an increased risk in women with active disease at the time of conception and in women who had undergone bowel resection during pregnancy. Birth weight and birth length corresponded to those in the reference population. The frequency of neonatal hyperbilirubinaemia was not higher in children of mothers with Crohn's disease than in children of healthy mothers. Treatment with sulphasalazine, salazosulphadimidine, and corticosteroids did not influence the course of pregnancy or the frequency of neonatal jaundice or malformations. Consequently, in Crohn's disease a pregnant woman should be given the same medical treatment as when not pregnant. Generally, the women should be advised preferably to conceive at a time when their bowel disease is inactive. The risk groups should be followed up with frequent obstetrical examinations throughout pregnancy.