Pregnant individuals with inflammatory bowel disease (IBD) have higher levels of pro-inflammatory immune molecules, known as cytokines, in their vaginal mucosa than their healthy counterparts, according to a new study published January 14, 2026 in the open-access journal PLOS One by Ana Maldonado-Contreras of University of Massachusetts Chan Medical School, U.S., and colleagues. However, the study also suggested that higher-quality diets, with more vegetables and fewer added sugars, are associated with lower levels of pro-inflammatory cytokines in pregnant women both with and without IBD.
Pregnant individuals with IBD are known to face increased risks of adverse pregnancy outcomes, including preterm birth. These individuals are also more likely to have bacterial vaginosis; a condition linked to poor pregnancy outcomes. However, little was known about the vaginal environment in pregnant IBD patients compared to their healthy counterparts.
In the new study, researchers recruited a total of 48 pregnant individuals in their third trimester: 23 with diagnosed IBD (18 with Crohn's disease and 5 with ulcerative colitis) and 25 healthy. More than half of the IBD participants were in remission at the time of recruitment. Participants provided vaginal swabs and completed three interviewer-led nutrition assessments of their dietary intake.
The researchers found that pregnant individuals with IBD, despite having similar bacteria in the vaginal mucosa as healthy individuals, had higher expression of pro-inflammatory cytokines, specifically IL-6, IL-8, and IL-17, and lower expression of a immune-regulating cytokine: IFN-γ and anti-inflammatory cytokine: IL-4. Across all women, those with and without IBD, a higher intake of vegetables or lower intake of added sugars was associated with higher levels of the beneficial microbe Lactobacillus crispatus, lower levels of the pro-inflammatory IFN-γ and increased levels of anti-inflammatory IL-4.
The study was limited by its modest sample size, and the fact that samples were collected only in the third trimester, preventing assessment of changes throughout pregnancy or conclusions about causation. However, the authors state that pregnant individuals with IBD have a pro-inflammatory vaginal environment even when in remission, which may help explain their increased risk of preterm birth.
In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/493F7g4
Citation: Vargas-Robles D, Yap YR, Singha B, Tien J, Purandare M, Rojas-Correa M, et al. (2026) Association of vaginal IL-4, IL-6, IL-8, IL-17, IFN-γ, and dietary intake with IBD status and vaginal microbiota in pregnant individuals. PLoS One 21(1): e0335178. https://doi.org/10.1371/journal.pone.0335178
Author countries: U.S.
Funding: We obtained financial support from The Leona M. and Harry B. Helmsley Charitable Trust to complete the study described in the manuscript. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
