Gestational Weight Gain and Birth Outcomes in a Large Canadian Cohort of Pregnant Persons with Inflammatory Bowel Disease

Introduction Pregnant persons with inflammatory bowel disease (IBD) are at increased risk of preterm delivery. We sought to characterize gestational weight gain (GWG) in this population and whether it is associated with birth outcomes. Methods Pregnant patients with ulcerative colitis (UC), Crohn’s disease (CD), and IBD-unclassified (IBD-U) were retrospectively identified at Mount Sinai Hospital from 2016 to 2020. Total GWG during pregnancy was categorized as inadequate, adequate, or excessive based on pre-pregnancy body mass index. Birth outcomes, including preterm delivery, small for gestational age (SGA) and large for gestational age (LGA), were recorded. Outcomes were compared amongst GWG groups. The association between gestational weight gain and outcomes was assessed using multiple logistic regression while controlling for confounders. Results 225 pregnancies were included (110 UC/IBD-U and 115 CD). The proportion of patients with inadequate, adequate, and excessive GWG was 21.3%, 40.4%, and 38.2%, respectively. The likelihood of preterm delivery did not differ among those with inadequate, adequate, and excessive GWG. The likelihood of SGA was lower in those with excessive GWG compared with those with inadequate and adequate GWG (7% vs. 21% and 20% respectively, P = 0.02). After adjusting confounders, the reduced odds of SGA associated with excessive GWG were only statistically significant among those with UC (adjusted odds ratio, 0.14; 95% CI: 0.03—0.74). Conclusions Both inadequate and adequate GWG are common in pregnant persons with IBD. In our cohort, inadequate GWG was not associated with adverse birth outcomes, while excessive GWG appears to be protective against SGA.