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

OBJECTIVE: To evaluate the effect of intrauterine autologous platelet-rich plasma instillation on endometrial thickness and reproductive outcomes in women with thin endometrium undergoing embryo transfer. DESIGN: Retrospective multicentre observational cohort study. SUBJECTS: A total of 280 embryo transfer cycles performed in women diagnosed with thin endometrium (3-6.9 mm). PATIENT(S): Women treated across a multicentre network of in vitro fertilization clinics in Spain and Italy between January 2020 and January 2024. EXPOSURE: Intrauterine autologous platelet-rich plasma instillation during hormone replacement therapy cycles, compared with standard management without platelet-rich plasma treatment. MAIN OUTCOME MEASURE(S): Change in endometrial thickness between the previous cycle and the study cycle, and rates of biochemical pregnancy, clinical pregnancy, ongoing pregnancy, and live birth. RESULT(S): 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; p < 0.0001). In multivariable logistic regression analyses adjusting for age, embryo-related factors, oocyte origin, pre-treatment endometrial thickness, preimplantation genetic testing for aneuploidy use, and number of embryos transferred, platelet-rich plasma treatment was not independently associated with biochemical pregnancy, clinical pregnancy, ongoing pregnancy, or live birth. CONCLUSION(S): Intrauterine autologous platelet-rich plasma was associated with a significant increase in endometrial thickness in women with thin endometrium, including those with less favourable 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.