Active Inflammatory Bowel Disease on Intestinal Ultrasound During Pregnancy Is Associated With an Increased Risk of Adverse Pregnancy and Neonatal Outcomes Independent of Clinical and Biochemical Disease Activity

Abstract

Background & aims: Clinically active inflammatory bowel disease (IBD) is associated with an increased risk of adverse pregnancy outcomes. However, the validity of clinical scores to assess antenatal disease activity is questionable. We aimed to assess whether active disease defined by intestinal ultrasound (IUS) may predict adverse pregnancy outcomes.

Methods: This international prospective cohort study recruited pregnant individuals with IBD from 2017 to 2023 from 3 specialist IBD pregnancy services. Participants underwent clinical assessments and fecal calprotectin (FCP) testing in the first (T1), second (T2), and third (T3) trimesters, and 6 weeks postpartum. IUS was performed in T1 or T2 when referral timing allowed. Univariable and multivariable log-binomial regression analyses were used to estimate the impact of IUS activity on pregnancy outcomes. Cohen's κ coefficients were used to determine agreement between FCP, IUS, and clinical disease activity.

Results: The study recruited 377 participants, 198 with Crohn's disease (CD), and 234 women underwent an IUS during pregnancy. A maximal bowel wall thickness (BWT) >6 mm in T2 was associated with a 4-fold increased risk of prematurity (relative risk [RR], 4.01; 95% confidence interval [CI], 1.26-12.72; P = .018) and 2-fold increased risk of low-birth-weight delivery (RR, 2.19; 95% CI. 1.01-4.72; P = .046). Hyperemia on IUS in T2 was associated with a 3-fold increase in preeclampsia risk (RR, 3.46; 95% CI, 1.03-11.12; P = .046). Each 1-mm increase in BWT in T2 was estimated to increase the risk of gestational diabetes (RR, 1.08; 95% CI, 1.088-1.089; P < .001) Agreement between clinical (Harvey Bradshaw index or Simple Clinical Colitis Activity Index) and IUS/FCP activity during pregnancy was weak, particularly for CD.

Conclusions: Active IBD on IUS in pregnancy is associated with an increased risk of adverse pregnancy outcomes, independent of clinical activity and FCP. Use of IUS monitoring antenatally should be considered to guide therapeutic decision-making.

Keywords: Fecal Calprotectin; Inflammatory Bowel Disease; Intestinal Ultrasound; Obstetric Outcomes; Pregnancy.