Article| Volume 46, ISSUE 3, P527-535, March 2023

Agonist long protocol improves outcomes of vitrified-warmed embryo transfer in repeatedly thin endometrium

Published:December 07, 2022DOI:


      Research question

      Does follicular stimulation using human menopausal gonadotrophin (HMG) after pituitary down-regulation by a GnRH agonist improve endometrial thickness (EMT) and clinical outcomes of frozen-thawed embryo transfer (FET; using vitrified-warmed embryos) in women with thin endometrium after intensified oestrogen administration (IOA)?


      This was a retrospective study. A total of 627 patients attempted 683 FET cycles with at least one previous history of thin endometrium. None of the cycles reached over 7 mm EMT after using oral and vaginal oestradiol for more than 21 days (IOA protocol). A total of 129 cycles proceeded with FET, 305 cycles were cancelled, and 249 cycles involved administration of HMG following GnRH agonist pituitary down-regulation (GnRH agonist + HMG protocol) for further endometrial preparation.


      EMT became significantly greater (7.18 ± 1.14 mm versus 6.13 ± 0.63 mm, P < 0.001) using GnRH agonist + HMG compared with previous IOA cycles, but this was not related to serum oestrogen concentrations. A total of 213 cycles after the GnRH agonist + HMG protocol proceeded with FET, showing a significantly increased clinical pregnancy rate, implantation rate and live birth rate compared with those after IOA.


      The GnRH agonist + HMG protocol for endometrial preparation in FET cycles improves EMT in women with a thin endometrium after IOA and showed significantly better clinical outcomes than IOA. The authors suggest that the GnRH agonist + HMG protocol should be used for EMT that is less than 7 mm after there has been no optimal response to IOA.


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      Peiyu Wang, MD, received her medical degree in obstetrics and gynaecology in 2010 and has worked at the Reproductive Medicine Center, The First Affiliated Hospital of Wenzhou Medical University, China, for 12 years. Her special research interests are treatment for thin endometrium, recurrent miscarriage and repeated implantation failure.
      Key message
      Follicular stimulation using human menopausal gonadotrophin after pituitary down-regulation by gonadotrophin-releasing hormone agonists can be used for endometrial preparation in frozen-thawed embryo transfer cycles to improve endometrial thickness and clinical outcomes when endometrial thickness is less than 7 mm after intensified oestrogen administration.