Labor and Delivery Outcomes in Australian Mothers after Kidney Transplantation

Background: Factors influencing high cesarean section rates among mothers with a kidney transplant remain unclear. Methods: Using linked Australia and New Zealand Dialysis and Transplant Registry (1970-2016) and perinatal datasets (1991-2013), we compared deliveries of women with a functioning kidney transplant to those without kidney replacement therapy (non-KRT). Results: Of 2,946,851 babies (1,627,408 mothers), 211 were born to 137 mothers with a kidney transplant. Overall cesarean sections rates were doubled in transplant cohort (63% versus 26% non-KRT, p<0.001) across all gestational periods compared to non-KRT cohort, and highest in preterm births (≥37 weeks: 48% versus 25%, p<0.001, 33-36 weeks: 77% versus 40%, p<0.001, and <33 weeks: 75% versus 41%, p<0.001). Cesarean section rates remained higher after adjusting for maternal factors (incidence rate ratio: 1.5; 95% CI: 1.3-1.7). In post-transplant women with past pregnancy, 53% with no previous cesarean sections had a cesarean section in the current pregnancy (versus 19% non-KRT, p<0.001). Mothers with a kidney transplant had less spontaneous labor than non-KRT mothers (30% versus 63%, p<0.001) and more planned deliveries (induced or elective cesarean sections) (70% versus 36%, p<0.001). Nearly half of the women with transplantation (45%) delivered by non-labor cesarean sections, mostly occurring preterm (<37 weeks: 70% versus ≥37 weeks: 30%, p=0.002). In the transplant cohort, the main indications for non-labor cesarean sections were hypertensive disorders of pregnancy and breech presentation (>50% versus 18% non-KRT cohort, p<0.001) and were linked to gestational age. Non-labor cesarean sections for fetal distress were higher in women with transplantation (10% versus 4% non-KRT, p=0.029). In the non-KRT cohort, previous cesarean sections were the main indication for non-labor cesarean sections (40% versus 24% transplant; p=0.055). Post-partum hemorrhage (13% vs 7% non-KRT, p=0.003) and fetal distress (18% versus 10% non-KRT, p=0.001) were higher among the transplant cohort. Conclusions: Women with a kidney transplant have higher rates of cesarean sections delivery even after accounting for maternal factors, preterm delivery and past cesarean sections compared to non-KRT cohorts.