Efficacy of platelet-rich plasma or plasma rich in growth factors in the treatment of thin endometrium: a systematic review and meta-analysis of randomized controlled trials.

Background: Thin endometrium is a recognized cause of implantation failure in assisted reproduction, and conventional treatments are frequently disappointing. Intrauterine infusion of autologous platelet-rich plasma (PRP) or plasma rich in growth factors (PRGF) has emerged as a candidate therapy, but the randomized evidence remains limited and inconsistent. Objective: To synthesize the randomized controlled evidence on the efficacy of intrauterine PRP or PRGF for women with thin endometrium, with clinical pregnancy as the primary outcome and biochemical pregnancy, endometrial thickness change, and cycle cancellation as secondary outcomes. Design: Systematic review and random-effects meta-analysis of randomized controlled trials (RCTs). Methods: PubMed, EMBASE, the Cochrane Library, and Web of Science were searched from inception to 30 April 2026. RCTs comparing intrauterine PRP or PRGF against a non-PRP control in women with thin endometrium were eligible. Risk of bias was appraised with the Cochrane RoB 2 tool and certainty of evidence with GRADE. Dichotomous outcomes were pooled as risk ratios (RR) and endometrial thickness change as a mean difference (MD), using random-effects models with the Hartung-Knapp adjustment. Heterogeneity was quantified with the I-squared statistic, and leave-one-out sensitivity analyses were performed. Results: Seven RCTs were included. For clinical pregnancy, five trials (343 participants) yielded a pooled RR of 2.32 (95% CI 1.02-5.31; p=0.047; I-squared=23.0%). PRP or PRGF significantly increased endometrial thickness (six trials, 370 participants; MD 0.94 mm, 95% CI 0.34-1.55; p=0.010) but with very high heterogeneity (I-squared=90.5%). Biochemical pregnancy (four trials, RR 2.32, 95% CI 0.71-7.52; p=0.108) and cycle cancellation (three trials, exploratory; RR 0.44, 95% CI 0.00-203.51; p=0.622) did not differ significantly. Leave-one-out analysis showed that the clinical-pregnancy result lost statistical significance when any of several trials was removed. Certainty of evidence was very low for pregnancy and thickness outcomes. Conclusion: Intrauterine PRP or PRGF reliably increases endometrial thickness and shows a marginally significant, fragile improvement in clinical pregnancy, without demonstrable benefit for biochemical pregnancy or cycle cancellation. Given the small number of trials, high risk of bias, and very low certainty of evidence, these findings should be regarded as preliminary and require confirmation in larger, rigorously designed RCTs. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/home, identifier CRD420261383681.