Original Article Can autologous platelet rich plasma expand endometrial thickness and improve pregnancy rate during frozen-thawed embryo transfer cycle? A randomized clinical trial Maryam Eftekhar a , Nosrat Neghab a, * , Elham Naghshineh b , Parisa Khani a a Reasearch and Clinical Center for Infertility, Yazd Reproductive Sciences Institute, Shahid Sadoughi University of Medical Sciences, Yazd, Iran b Department of Obstetrics and Gynecology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran article info Article history: Accepted 3 July 2018 Keywords: Platelet-rich plasma Thin endometrium Pregnancy rate abstract Objective: One of the important aspects involved in achieving optimal outcomes after assisted repro- ductive treatment (ART) is the endometrium. Some cycles are cancelled due to inadequate endometrial growth in ART. In this clinical trial, we evaluated the effectiveness of platelet-rich plasma (PRP) in the treatment of thin endometrium. Materials and methods: In this randomized clinical trial, 83 women with poor endometrial response to standard hormone replacement therapy (HRT) (endometrium thickness < 7 mm) in the 13th day of the cycle in a frozen-thawed embryo transfer (FET) were entered in two groups. In the PRP group (n ¼ 40), in addition to HRT, 0.5e1 cc of PRP was infused into the uterine cavity on the 13th day of HRT cycle. The control group (n ¼ 43) was only received HRT. If endometrial thickness failed to increase after 48 h, PRP infusion was repeated in the same cycle. When the endometrium thickness reached 7 mm, embryo transfer was done. Finally, endometrial thickness, chemical, clinical, and ongoing pregnancy rates were compared between two groups. Results: Endometrial thickness increased significantly to 8.67 ± 0.64 in PRP group than in controls (p ¼ 0.001). This increase was higher in women who conceived in PRP group (p value: 0.031). The im- plantation rate and per-cycle clinical pregnancy rate were significantly higher in PRP group (p ¼ 0.002 and 0.044, respectively (p ¼ 0.002). Conclusion: PRP may be effective in improving the endometrial growth, and possibly pregnancy out- comes in women with a thin endometrium. © 2018 Taiwan Association of Obstetrics & Gynecology. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Introduction It was established that pregnancy rate was affected negatively by endometrial thickness <7 mm and thin endometrium resulted in significantly lower implantation and pregnancy rates and also correlated with a higher risk of miscarriage. Therefore, the thin endometrium is an extremely poor factor that interferes with an ongoing pregnancy [1,2]. Immunological mechanisms such as growth factors, hormones, and cytokines, which are produced by decidual cells have very important and crucial role in the implantation in the endometrium [2]. Some frozen-thawed embryo transfer (FET) cycles are cancelled due to the thin endometrium, and there is no conventional protocol for this condition. Hormonal manipulation like an extended dose of estrogen or improving endometrial perfusion by low dose aspirin, Pentoxifylline and vitamin E, Sildenafil, and new modalities like Granulocyte colony-stimulating factor (G-CSF) are used for endome- trial expansion [3]. Combined treatment with pentoxifylline and vitamin E, 6e9 months before embryo transfer, significantly improved the pregnancy rate by increasing endometrial thickness [4]. Intrauterine perfusion with -G-CSF has been used for thin endo- metrium, but there isn't any proved evidence in this treatment [5e7]. * Corresponding author. University of Medical Sciences and Health Services, Yazd Research and Clinical Centre for Infertility, Bouali Ave, Safaeyeh, Yazd, Iran. E-mail addresses: eftekhar@ssu.ac.ir (M. Eftekhar), nosrat20@yahoo.com, nosratneghab@ssu.ac.ir (N. Neghab), Naghshineh@med.mui.ac.ir (E. Naghshineh), pkhani55@ssu.ac.ir (P. Khani). Contents lists available at ScienceDirect Taiwanese Journal of Obstetrics & Gynecology journal homepage: www.tjog-online.com https://doi.org/10.1016/j.tjog.2018.10.007 1028-4559/© 2018 Taiwan Association of Obstetrics & Gynecology. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). Taiwanese Journal of Obstetrics & Gynecology 57 (2018) 810e813