Inadequate Gestational Weight Gain, the Hidden Link Between Maternal IBD and Adverse Pregnancy Outcomes: Results from the Norwegian Mother and Child Cohort Study

Background: Patients with inflammatory bowel disease (IBD) are in general prone to weight loss. We explored the risk of inadequate gestational weight gain (GWG), and the impact of GWG on adverse pregnancy outcomes, among mothers with IBD in the Norwegian Mother and Child Cohort Study (MoBa). Methods: The MoBa with 95,200 mothers enrolled from 1999 to 2008, comprised 217 mothers with ulcerative colitis and 166 with Crohn's disease. Demographics were ascertained through a basic questionnaire before the first ultrasound visit and an IBD history and disease activity during pregnancy through a questionnaire mailed out in 2013. Inadequate GWG was based on the US Institute of Medicine recommendations. The associations between IBD and inadequate GWG or adverse pregnancy outcomes were explored, adjusted for diabetes, hypertension, smoking, maternal age, education, and disease activity. Results: Mothers with Crohn's disease (34.3%) and ulcerative colitis (26.7%) were more frequently exposed to inadequate GWG compared with non-IBD mothers (19.4%) (adjusted odds ratio [aOR] = 2.02, 95% confidence interval [CI], 1.42-2.86 and aOR = 1.46, 95% CI, 1.04-2.05, respectively). Mothers with IBD with inadequate GWG (exposed) had a 2-fold risk of small for gestational age infants compared with exposed non-IBD mothers (aOR = 1.93, 95% CI, 1.13-3.29). Exposed mothers with Crohn's disease and ulcerative colitis had a several-fold increased risk of small for gestational age compared with nonexposed IBD mothers (aOR = 4.5, 95% CI, 1.3-16.2, aOR = 5.5, 95% CI, 1.6-18.5). Disease activity was associated with reduced GWG (<13 kg compared with >17.5 kg) (aOR = 3.34, 95% CI, 1.33-8.38). Conclusions: Inadequate GWG should be considered as a risk factor for adverse pregnancy outcomes or as a marker of disease activity.