INTRODUCTION: Women with inflammatory bowel disease (IBD) who have IBD surgery before pregnancy have an increased risk of adverse maternal and fetal outcomes. Very few studies have examined the risks of gastrointestinal complications during pregnancy in this group of women. METHODS: Using the Danish national registries, we identified live born children of mothers with ulcerative colitis (UC) or Crohn's disease (CD) who had IBD surgery before pregnancy. We compared the outcomes of ileus/bowel obstruction during pregnancy in women with UC or CD who had surgery compared with women with UC or CD who did not have surgery before pregnancy. RESULTS: IBD surgery before pregnancy was more common in women with CD than in women with UC (31.5% vs 6.3%). For live births, 7.1% of mothers with UC surgery and 1.8% of mothers with CD surgery had a diagnosis of ileus/bowel obstruction during pregnancy. Patients who had UC surgery had an adjusted odds ratio (aOR) of 71.98 (95% confidence interval [CI] 33.13-156.39) of an ileus/bowel obstruction compared with those with UC who had not had surgery. For UC: permanent ileostomies: aOR 128.69 (95% CI 57.57-287.63) and ileal pouch-anal anastomosis with diverting ostomy: aOR 40.14 (95% CI 11.19-143.96). Patients who had CD surgery had an aOR of 10.00 (95% CI 4.64-21.55). For CD: intestinal surgery (no stoma): aOR 7.96 (95% CI 3.48-18.22) and intestinal surgery (with stoma): aOR 43.89 (95% CI 17.40-110.69). DISCUSSION: There is a significant risk of ileus/bowel obstruction during pregnancy in women who had IBD surgery before pregnancy.