Pregnancy guidelines for women with inflammatory bowel disease [IBD] provide recommendations regarding anti-TNF cessation during pregnancy, in order to limit foetal exposure. Although infliximab [IFX] leads to higher anti-TNF concentrations in cord blood than adalimumab [ADA], the recommendations are similar. We aimed to demonstrate the effect of anti-TNF cessation during pregnancy on foetal exposure, for IFX and ADA separately.
We conducted a prospective single-center cohort study. Women with IBD, using IFX or ADA, were followed-up during pregnancy. In case of sustained disease remission, anti-TNF was stopped in the third trimester. At the birth, the anti-TNF concentration was measured in the cord blood. A linear regression model was developed to demonstrate anti-TNF concentration in cord blood at birth. In addition, outcomes such as disease activity, pregnancy outcomes and 1-year health outcomes of infants were collected.
We included 131 pregnancies that resulted in a live birth [73 IFX, 58 ADA]. At birth, 94 cord blood samples were obtained [52 IFX, 42 ADA], showing significantly higher levels of IFX than ADA [p < 0.0001]. Anti-TNF type and stop week were used in the linear regression model. During the third trimester, IFX transportation over the placenta increased exponentially; however, ADA transportation was limited and increased in a linear fashion. Overall, health outcomes were comparable.
Our linear regression model shows that ADA may be continued longer during pregnancy, because transportation over the placenta is lower than for IFX. This may reduce relapse risk of the mother, without increasing foetal anti-TNF exposure.