Both ulcerative colitis and Crohn’s disease have a predilection for young adults, with peak occurrence between the second and fourth decade of life. It is therefore not at all uncommon to encounter a woman with inflammatory bowel disease (IBD) who is pregnant or who wishes to become pregnant. The issues of particular interest to both the patient with IBD and her physician are the ability to conceive, the influence of IBD on pregnancy, the influence of pregnancy on the underlying bowel disease, and the effect of therapy on the fetus.

Fertility. Ulcerative colitis appears to have little effect on fertility. Crohn’s disease, however, has been associated with decreased fertility rates. Though reported fertility rates vary by study, most agree that conception among women with Crohn’s disease generally occurs during periods of disease remission. In addition, surgical removal of diseased bowel has been associated with restoration of normal fertility, with postoperative rates of conception approximating those of the population at large. Other factors that contribute to diminished fertility in Crohn’s disease include adnexal involvement by the chronic inflammatory process resulting in tubal occlusion, decreased libido associated with the systemic illness, nutritional deficiencies, and the presence of perineal disease, which may result in a physical or psychologic impediment to intercourse.

Influence of IBD on Pregnancy. In general, ulcerative colitis and Crohn’s disease do not have a detrimental effect on the outcome of pregnancy. The incidence of live births, congenital anomalies, spontaneous abortions, and stillbirths is similar to that in pregnancies without associated IBD. Exceptions to these optimistic findings indicate that the risk of spontaneous abortion and prematurity may be greater in women whose disease is active at the time of conception than in those who conceive when their disease is quiescent. Women with IBD who experience severe exacerbations during pregnancy and those in whom Crohn’s disease develops for the first time during gestation may also have increased fetal risk.

Previous bowel resection or proctocolectomy with ileostomy does not affect the course of pregnancy. The mode of delivery should be based on obstetric indications. Displacement, enlargement, and prolapse of the ileal stoma can occur, however.

Influence of Pregnancy on IBD. The effect of pregnancy on IBD is variable and appears to be related to disease activity at the time of conception. Of patients whose IBD is quiescent at the onset of pregnancy, approximately 75% remain free of symptoms throughout gestation. If relapse does occur, it usually does so during the first trimester in both ulcerative colitis and Crohn’s disease. In the less common situation in which pregnancy occurs in the presence of active disease, the prognosis is less favorable. Approximately 70% of these women show no improvement in their disease or become worse as gestation progresses. Although many reports suggest that women who manifest the onset of IBD during pregnancy have the highest risk of serious problems, more recent clinical data do not unanimously reflect this experience. When IBD does first arise during pregnancy, it is most likely to do so in the first or second trimester. Disease behavior during one pregnancy is not predictive of behavior during subsequent pregnancies.

Treatment. The management of IBD differs little during pregnancy. Maintenance therapy with sulfasalazine can be continued throughout pregnancy in women who have taken it before conception. The drug may also be initiated to treat exacerbations. There is no evidence that the medication should be discontinued near the time of delivery, nor that use during breast-feeding harms the newborn. If necessary, corticosteroids may be used to manage IBD during pregnancy and lactation. In general, patients on chronic corticosteroid therapy are given increased doses for labor and delivery. Metronidazole and the immunosuppressives 6-mercaptopurine and azathioprine should be avoided during pregnancy because of possible teratogenic effects of these agents.