Background: The inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC) have been associated with an increased risk of preterm birth.
Material and methods: We identified all 246 singleton preterm births among women with IBD between July 2006 and December 2010 as cases and an equal number of controls with IBD from the Swedish national health registers, matched by maternal age, parity and IBD diagnosis (CD/UC). From register data and medical charts, we obtained information on reproductive history, comorbidity, disease activity and drug treatment (corticosteroids, 5-aminosalicylates, sulfasalazine, thiopurines and anti-TNF) as risk factors for preterm birth. Associations were estimated using conditional logistic regression and results were presented as odds ratios (OR) with 95% confidence intervals (CI).
Results: Previous preterm birth was more common among cases, OR 6.13 (95%CI: 2.51-15.01). Significant activity at any time during pregnancy (OR: 2.20; 95%CI: 1.37-3.53), and in particular both in early and in late pregnancy, was more common for cases (OR: 4.78 95%; CI: 2.10-10.9). The OR for immunosuppressive treatment with thiopurines or anti-TNF was 1.88 (1.04-3.39) without significant activity and 12.78 (95%CI: 3.68-44.72) with. The risk for women who discontinued thiopurines was 6.56 (1.44-29.82).
Conclusions: Significant activity and immunosuppressive treatment was associated with preterm birth, particularly in women with both. The existing recommendations to aim at maintaining quiescent disease during pregnancy, even if it means continuing immunosuppressive treatment, are rational.
Keywords: Crohn’s disease; IBD; inflammatory bowel disease; pregnancy; preterm birth; ulcerative colitis.