Placental inflammation is not increased in inflammatory bowel disease

Women with inflammatory bowel disease (IBD) are at increased risk for adverse birth outcomes such as preterm delivery and small for gestational age (SGA) infants. Most recognized cases of fetal growth restriction in singleton pregnancies have underlying placental causes. However, studies in IBD examining poor birth outcomes have focused on maternal factors. We examined whether women with IBD have a higher rate of placental inflammation than non-IBD controls.

Between 2008 and 2011, the placental tissue of 7 ulcerative colitis, 5 Crohn's disease, and 2 IBD-unclassified subjects enrolled in the Pregnancy in Inflammatory Bowel Disease and Neonatal Outcome (PIANO) registry were evaluated for villitis, deciduitis, and chorioamnionitis with/without a fetal inflammatory response. The history and birth outcomes of all IBD subjects were reviewed and matched to 26 non-IBD controls by gestational age at delivery.

Of women with IBD, 29% delivered preterm infants and 21% delivered SGA infants. Half of the IBD patients had mild-moderate disease flares during pregnancy. Five (36%) patients required corticosteroids, 2 (14%) were maintained on an immunomodulator, and 3 (21%) others received tumor necrosis factor-alpha inhibitors during their pregnancy. Chorioamnionitis was the only identified placental pathology present in the placentas reviewed, occurring less frequently in cases compared to controls (7% vs. 27%, P=0.32).

Placental inflammatory activation does not appear to be responsible for the increase in adverse birth outcome in women with IBD. Further studies are necessary to validate these findings in IBD to explain poor birth outcomes.