Safety Prediction of Infants Born to Mothers with Crohn's Disease Treated with Biological Agents in the Late Gestation Period.

Objectives: Knowledge gaps exist in the use of biologics for pregnant patients with Crohn's disease (CD), especially the usage of ustekinumab (UST) and infliximab (IFX) infusion during the late gestation period. In this case series, we investigated perinatal and neonatal outcomes and pharmacokinetics of these biologics in pregnant CD patients.

Methods: Pregnant CD patients under treatment with IFX or UST during January 2017 to December 2019 were monitored. Growth and development of their babies were followed up to six months. Drug concentrations were measured in maternal peripheral and cord blood at delivery and infants' blood at six months of age.

Results: Four cases were kept IFX treatment until late gestation (median last dose: 31.2 weeks). One case received UST until 23 weeks of gestation. All cases were in clinical remission but moderately undernourished. Babies were delivered by cesarean section at full term without any complications or congenital abnormalities. No growth or developmental defects and no susceptibility to infections were observed by six months. However, two babies whose mothers received IFX after 30 weeks of gestation were detected IFX in their blood at six months of age (0.94 and 0.24 pg/ml). Concentrations of UST in maternal and cord blood were 267.7 and 756.5 ng/ml, respectively. UST was not detected in the infant at six months of age.

Conclusions: Administration of UST or IFX to pregnant patients with CD is safe, particularly IFX to be given in the late gestation period. Understanding of the pharmacokinetics of biologics in maternal-infant interactions may improve the management of pregnant CD patients.