Background: Neither conceptions and pregnancy outcomes nor the safety of medications for childbearing inflammatory bowel disease (IBD) patients has been investigated in Asia. The aim of this study is to analyse conception and pregnancy outcomes of Japanese female IBD patients. Methods: We conducted a retrospective cohort study of pregnant IBD patients at 6 institutions. The incidences of abortion, Caesarean delivery, low birth weight (LBW) (< 2500. g), and congenital malformation were analysed in these patients. Risk factors associated with adverse outcomes in IBD patients were also assessed. Results: A total of 325 patients experienced 534 conceptions. Among these, 303 conceptions (57%) were observed during/after disease onset. Although conceptions and pregnancy outcomes after disease onset were comparable to the observed levels prior to disease onset in UC patients, the incidences of spontaneous abortion (OR 5.3; 95%CI 1.1-25.0) and Caesarean delivery (OR 4.8; 95%CI 1.5-15.0) were significantly higher in Crohn's disease (CD) patients whose conceptions occurred after disease onset compared to CD patients whose conceptions occurred before disease onset. The incidences of spontaneous abortion, LBW, and Caesarean delivery were higher in CD patients who had a history of surgery for perianal lesions than in those who did not have perianal lesions or who had ulcerative colitis (UC). In the IBD patients studied after disease onset, independent risk factors for spontaneous abortions included a history of previous treatment for sterility (OR 2.9; 95%CI 1.2-7.0). Independent risk factors for Caesarean operation (OR 4.1, 95% CI: 1.7-10.1) and LBW (OR 3.5, 95% CI: 1.3-9.1) included a history of bowel resection for the treatment of IBD. Congenital malformation was not associated with the factors of type of disease, smoking, and previous surgery. Conclusion: In Japanese UC patients, conception and pregnancy outcomes after disease onset were comparable to the outcomes observed prior to disease onset, whereas CD appeared to be associated with adverse outcomes. Caesarean operation and LBW were more frequently observed in CD patients who had a history of surgery for perianal lesions and bowel resection.
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