Comparison of pregnancy outcomes in Dutch kidney recipients with and without calcineurin inhibitor exposure; a retrospective study.

Within pregnancies occurring between 1986-2017 in Dutch kidney transplant recipients (KTR), we retrospectively compared short-term maternal and fetal outcomes between patients on calcineurin inhibitor (CNI) based (CNI+) and CNI free -immunosuppression (CNI-). We identified 129 CNI+ and 125 CNI- pregnancies in 177 KTR. Demographics differed with CNI+ having higher body mass index (p=0.045), shorter transplant-pregnancy interval (p<0.01), later year of transplantation and -pregnancy (p<0.01). Serum creatinin levels were numerically higher in CNI+ in all study phases, but only reached statistical significance in third trimester (127 vs 105 µmol/L; p<0.01), where the percentual changes from preconceptional level also differed (+3.1% versus -2.2% in CNI-; p=0.05). Postpartum both groups showed 11-12% serum creatinin rise from preconceptional level. Incidence of low birth weight (LBW) tended to be higher in CNI+ (52% vs 46%; p=0.07). Both groups showed equal high rates of preterm delivery. Using CNIs during pregnancy lead to a rise in creatinin in the third trimester but does not negatively influence the course of graft function in the first year postpartum or direct fetal outcomes. High rates of preterm delivery and LBW in KTR, irrespective of CNI use, classify all pregnancies as high-risk.