Adverse Pregnancy Outcomes in Solid Organ Transplant Recipients: A Systematic Review and Meta-Analysis

IMPORTANCE Transplant recipients experience high rates of adverse pregnancy outcomes; however, contemporary estimates of the association between solid organ transplantation and adverse pregnancy outcomes are lacking. OBJECTIVE To evaluate the association between solid organ transplantation and adverse pregnancy outcomes and to quantify the incidence of allograft rejection and allograft loss during pregnancy. DATA SOURCES PubMed/MEDLINE, EMBASE and Scopus databases were searched from January 1, 2000, to June 20, 2024, and reference lists were manually reviewed. STUDY SELECTION Cohort and case-control studies that reported at least 1 adverse pregnancy outcome in pregnant women with solid organ transplantation vs without solid organ transplant or studies that reported allograft outcomes in pregnant women with solid organ transplantation were included following independent dual review of abstracts and full-text articles. DATA EXTRACTION AND SYNTHESIS Two investigators abstracted data and independently appraised risk of bias using the Newcastle Ottawa Scale. A random-effects model was used to calculate overall pooled estimates using the DerSimonian-Laird estimator. Reporting followed the Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline. MAIN OUTCOMES AND MEASURES Primary pregnancy outcomes were preeclampsia, preterm birth (<37 weeks), and low birth weight (<2500 g). Secondary pregnancy outcomes were live birth rate, gestation, very preterm birth (<32 weeks), very low birth weight (<1500 g), and cesarean delivery. Allograft outcomes were allograft loss and rejection during pregnancy. RESULTS Data from 22 studies and 93 565 343 pregnancies (4786 pregnancies in solid organ transplant recipients) were included; 14 studies reported adverse pregnancy outcomes, and 13 studies provided data for allograft outcomes. Pregnancies in organ transplant recipients were associated with significantly increased risk of preeclampsia (adjusted odds ratio [aOR], 5.83 [95% CI, 3.45-9.87]; I² = 77.4%), preterm birth (aOR, 6.65 [95% CI, 4.09-12.83]; I² = 81.8%), and low birth weight (aOR, 6.51 [95% CI, 2.85-14.88]; I² = 90.6%). The incidence of acute allograft rejection was 2.39% (95% CI, 1.20%-3.96%; I² = 68.5%), and the incidence of allograft loss during pregnancy was 1.55% (95% CI, 0.05%-4.44%; I² = 69.2%). CONCLUSIONS AND RELEVANCE In this systematic review and meta-analysis, pregnancies in recipients of a solid organ transplant were associated with a 4 to 6 times increased risk of preeclampsia, preterm birth, and low birth weight during pregnancy. There was a low overall risk of graft rejection or loss during pregnancy.