Autologous platelet-rich plasma on endometrial growth and reproductive outcomes in women with thin endometrium: a multicenter cohort study

OBJECTIVE: To evaluate the effect of intrauterine autologous platelet-rich plasma (PRP) instillation on endometrial thickness and reproductive outcomes in women with thin endometrium undergoing embryo transfer. DESIGN: Retrospective multicenter observational cohort study. SUBJECTS: A total of 280 embryo transfer cycles performed in women diagnosed with thin endometrium (3-6.9 mm). PATIENTS: Women treated across a multicenter network of in vitro fertilization clinics in Spain and Italy between January 2020 and January 2024. EXPOSURE: Intrauterine autologous PRP instillation during hormone replacement therapy cycles, compared with standard management without PRP treatment. MAIN OUTCOME MEASURES: Change in endometrial thickness between the previous cycle and the study cycle, and rates of biochemical pregnancy, clinical pregnancy, ongoing pregnancy, and live birth. RESULTS: Intrauterine autologous PRP instillation was associated with a significantly greater increase in endometrial thickness compared with non-PRP (0.95 ± 0.99 mm vs. 0.16 ± 0.77 mm). In multivariable logistic regression analyses adjusting for age, embryo-related factors, oocyte origin, pretreatment endometrial thickness, preimplantation genetic testing for aneuploidy use, and number of embryos transferred, PRP treatment was not independently associated with biochemical pregnancy, clinical pregnancy, ongoing pregnancy, or live birth. CONCLUSION: Intrauterine autologous PRP was associated with a significant increase in endometrial thickness in women with thin endometrium, including those with less favorable baseline characteristics. However, no corresponding improvement in reproductive outcomes was observed, indicating that embryo-related factors may play a more important role than endometrial thickness in determining treatment success.