Long-term impact of pregnancy on mortality and graft outcomes in kidney transplant recipients: a systematic review and meta-analysis

Abstract

Background and aim Pregnancy in kidney transplant recipients involves complex physiological changes that could potentially impact long-term graft function and survival. Despite some evidence suggesting minimal long-term effects on graft survival, conflicting results on graft function and timing-related risks highlight the need for a comprehensive review. This systematic review and meta-analysis aims to evaluate long-term impact of pregnancy on patient survival, graft failure, serum creatinine levels, estimated glomerular filtration rate (eGFR), and proteinuria in kidney transplant recipients. Materials and methods We conducted a systematic review and meta-analysis adhering to PRISMA guidelines and registered with PROSPERO (CRD42024569702). We searched PubMed, Scopus, Web of Science, Cochrane Library, and Ovid MEDLINE. Studies were eligible if they provided data on adult kidney transplant recipients (> 18 years) who became pregnant post-transplant and included a control group of non-pregnant or non-conceived individuals. Results Among the 6118 results screened, 19 studies met the eligibility criteria and were included in the meta-analysis. The risk of allograft failure or graft loss was similar between pregnant and non-pregnant controls (OR 1.13, 95% CI 0.83-1.53, p = 0.43), with a slightly higher adverse outcome rate in pregnant patients (25.4 vs. 19.8%). All-cause mortality risk was also comparable (OR 0.63, 95% CI 0.38-1.07, p = 0.09), with low heterogeneity (I-2 = 12%). Creatinine levels were significantly lower before pregnancy compared to after delivery (SMD - 0.33, 95% CI - 0.52 to - 0.14, p = 0.0008). Conclusion Pregnancy in kidney transplant recipients leads to increased creatinine levels in postpartum but does not significantly affect long-term graft survival. While creatinine levels generally decrease during pregnancy, they show variability by trimester. The risk of allograft failure and mortality is similar between pregnant and non-pregnant recipients though adverse outcomes are slightly more frequent in pregnant patients, emphasizing the need for an optimal follow-up protocol of pregnant transplant recipients that takes trimester-specific graft function variations into consideration and that establishes clear thresholds for further evaluation and timely intervention.