Skip to main content
Log in

Preparation of endometrium for frozen embryo replacement cycles: a systematic review and meta-analysis

  • Review
  • Published:
Journal of Assisted Reproduction and Genetics Aims and scope Submit manuscript

Abstract

Purpose

The purpose of this study was to evaluate the best protocol to prepare endometrium for frozen embryo replacement (FER) cycles.

Methods

This study is a systematic review and meta-analysis. Following PubMed and OvidSP search, a total of 1166 studies published after 1990 were identified following removal of duplicates. Following exclusion of studies not matching our inclusion criteria, a total of 33 studies were analyzed. Primary outcome measure was live birth. The following protocols, including true natural cycle (tNC), modified natural cycle (mNC), artificial cycle (AC) with or without suppression, and mild ovarian stimulation (OS) with gonadotropin (Gn) or aromatase inhibitor (AI), were compared.

Results

No statistically significant difference for both clinical pregnancy and live birth was noted between tNC and mNC groups. When tNC and AC without suppression groups are compared, there was a statistically significant difference in clinical pregnancy rate in favor of tNC, whereas it failed to reach statistical significance for live birth. When tNC and AC with suppression groups are compared, there was a statistically significant difference in live birth rate favoring the latter. Similar pregnancy outcome was noted among mNC versus AC with or without suppression groups. Similarly, no difference in clinical pregnancy and live birth was noted when ACs with or without suppression groups are compared.

Conclusions

There is no consistent superiority of any endometrial preparation for FER. However, mNC has several advantages (being patient-friendly; yielding at least equivalent or better pregnancy rates when compared with tNC and AC with or without suppression; may not require LPS). Mild OS with Gn or AI may be promising.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

Similar content being viewed by others

References

  1. D’Angelo A. Ovarian hyperstimulation syndrome prevention strategies: cryopreservation of all embryos. Semin Reprod Med. 2010;28(6):513–8. doi:10.1055/s-0030-1265679.

    Article  PubMed  Google Scholar 

  2. Taylor TH, Patrick JL, Gitlin SA, Michael Wilson J, Crain JL, Griffin DK. Outcomes of blastocysts biopsied and vitrified once versus those cryopreserved twice for euploid blastocyst transfer. Reprod Biomed Online. 2014;29(1):59–64. doi:10.1016/j.rbmo.2014.03.001.

    Article  PubMed  Google Scholar 

  3. Bourgain C, Devroey P. The endometrium in stimulated cycles for IVF. Hum Reprod Update. 2003;9(6):515–22.

    Article  PubMed  Google Scholar 

  4. European IVFMC, European Society of Human R, European IVFMC, European Society of Human R, Embryology, Kupka MS, D’Hooghe T, Ferraretti AP, et al. Assisted reproductive technology in Europe, 2011: results generated from European registers by ESHRE. Hum Reprod. 2016;31(2):233–48. doi:10.1093/humrep/dev319.

    Google Scholar 

  5. Kupka MS, Ferraretti AP, de Mouzon J, Erb K, D’Hooghe T, Castilla JA, et al. Assisted reproductive technology in Europe, 2010: results generated from European registers by ESHREdagger. Hum Reprod. 2014;29(10):2099–113. doi:10.1093/humrep/deu175.

    Article  CAS  PubMed  Google Scholar 

  6. CDC. Assisted reproductive technology, National summary report. 2013.

  7. Glujovsky D, Dominguez M, Fiszbajn G, Papier S, Lavolpe M, Sueldo C. A shared egg donor program: which is the minimum number of oocytes to be allocated? J Assist Reprod Genet. 2011;28(3):263–7. doi:10.1007/s10815-010-9511-7.

    Article  PubMed  Google Scholar 

  8. Groenewoud ER, Cantineau AE, Kollen BJ, Macklon NS, Cohlen BJ. What is the optimal means of preparing the endometrium in frozen-thawed embryo transfer cycles? A systematic review and meta-analysis. Hum Reprod Update. 2013;19(5):458–70. doi:10.1093/humupd/dmt030.

    Article  PubMed  Google Scholar 

  9. Andersen AG, Als-Nielsen B, Hornnes PJ, Franch AL. Time interval from human chorionic gonadotrophin (HCG) injection to follicular rupture. Hum Reprod. 1995;10(12):3202–5.

    CAS  PubMed  Google Scholar 

  10. Park SJ, Goldsmith LT, Skurnick JH, Wojtczuk A, Weiss G. Characteristics of the urinary luteinizing hormone surge in young ovulatory women. Fertil Steril. 2007;88(3):684–90. doi:10.1016/j.fertnstert.2007.01.045.

    Article  CAS  PubMed  Google Scholar 

  11. Bjuresten K, Landgren BM, Hovatta O, Stavreus-Evers A. Luteal phase progesterone increases live birth rate after frozen embryo transfer. Fertil Steril. 2011;95(2):534–7. doi:10.1016/j.fertnstert.2010.05.019.

    Article  CAS  PubMed  Google Scholar 

  12. Fauser BC, de Jong D, Olivennes F, Wramsby H, Tay C, Itskovitz-Eldor J, et al. Endocrine profiles after triggering of final oocyte maturation with GnRH agonist after cotreatment with the GnRH antagonist ganirelix during ovarian hyperstimulation for in vitro fertilization. J Clin Endocrinol Metab. 2002;87(2):709–15. doi:10.1210/jcem.87.2.8197.

    Article  CAS  PubMed  Google Scholar 

  13. Casper RF, Yanushpolsky EH. Optimal endometrial preparation for frozen embryo transfer cycles: window of implantation and progesterone support. Fertil Steril. 2016;105(4):867–72. doi:10.1016/j.fertnstert.2016.01.006.

    Article  CAS  PubMed  Google Scholar 

  14. Eftekhar M, Rahsepar M, Rahmani E. Effect of progesterone supplementation on natural frozen-thawed embryo transfer cycles: a randomized controlled trial. Int J Fertil Steril. 2013;7(1):13–20.

    PubMed  PubMed Central  Google Scholar 

  15. Dal Prato L, Borini A, Cattoli M, Bonu MA, Sciajno R, Flamigni C. Endometrial preparation for frozen-thawed embryo transfer with or without pretreatment with gonadotropin-releasing hormone agonist. Fertil Steril. 2002;77(5):956–60.

    Article  PubMed  Google Scholar 

  16. van de Vijver A, Polyzos NP, Van Landuyt L, De Vos M, Camus M, Stoop D, et al. Cryopreserved embryo transfer in an artificial cycle: is GnRH agonist down-regulation necessary? Reprod Biomed Online. 2014;29(5):588–94. doi:10.1016/j.rbmo.2014.08.005.

    Article  PubMed  Google Scholar 

  17. Van der Auwera I, Meuleman C, Koninckx PR. Human menopausal gonadotrophin increases pregnancy rate in comparison with clomiphene citrate during replacement cycles of frozen/thawed pronucleate ova. Hum Reprod. 1994;9(8):1556–60.

    PubMed  Google Scholar 

  18. Peeraer K, Couck I, Debrock S, De Neubourg D, De Loecker P, Tomassetti C, et al. Frozen-thawed embryo transfer in a natural or mildly hormonally stimulated cycle in women with regular ovulatory cycles: a RCT. Hum Reprod. 2015;30(11):2552–62. doi:10.1093/humrep/dev224.

    Article  PubMed  Google Scholar 

  19. Ezoe K, Daikoku T, Yabuuchi A, Murata N, Kawano H, Abe T, et al. Ovarian stimulation using human chorionic gonadotrophin impairs blastocyst implantation and decidualization by altering ovarian hormone levels and downstream signaling in mice. Mol Hum Reprod. 2014;20(11):1101–16. doi:10.1093/molehr/gau065.

    Article  PubMed  Google Scholar 

  20. Horcajadas JA, Minguez P, Dopazo J, Esteban FJ, Dominguez F, Giudice LC, et al. Controlled ovarian stimulation induces a functional genomic delay of the endometrium with potential clinical implications. J Clin Endocrinol Metab. 2008;93(11):4500–10. doi:10.1210/jc.2008-0588.

    Article  CAS  PubMed  Google Scholar 

  21. Glujovsky D, Pesce R, Fiszbajn G, Sueldo C, Hart RJ, Ciapponi A. Endometrial preparation for women undergoing embryo transfer with frozen embryos or embryos derived from donor oocytes. Cochrane Database Syst Rev. 2010;1:CD006359. doi:10.1002/14651858.CD006359.pub2.

    PubMed  Google Scholar 

  22. El Bahja D. Frozen embryo transfer protocol: does spontaneous cycle give good results? Gynecol Obstet Fertil. 2012.

  23. Yishia D. Do we need to artificially prepare the endometrium for frozen embryo transfer in normal cycling women? A controlled study. Fertil Steril. 2001;76:112.

    Google Scholar 

  24. Belaisch-Allart J. Clinical management of a frozen–thawed embryo transfer cycle. Abstracts of the 10th Annual Meeting of the ESHRE Brussels. 1994:138-9.

  25. Gonzales J. Natural cycle and hormonal replacement in FET: implantation and pregnancy rates. Abstract Book of the 48th Meeting of the American Fertility Society. 1992:42.

  26. Cattoli M. Arandomized prospective studyon cryopreserved-thawedembryo transfer: natural versus homrone replacement cycles. Abstracts of the 10th Annual Meeting of the ESHRE Brussels. 1994;356:139.

  27. Alama P. Higher ongoing pregnancy rates in blastocyst transfer of frozen-thawed embryos in natural cycles than in hormone replacement therapy cycles. Fertil Steril. 2007;88:161.

    Article  Google Scholar 

  28. Dolan P. Natural cycles and estrogen/progestone induced cycles produce an equallly receptive endometrium for implantation of cryopreserved embryos. Hum Reprod (Oxford, England) 1991:16.

  29. Lee S. Comparison of clinical outcome of frozen–thawed embryo transfer cycles between natural and artificial (hormone-treated) cycles. Hum Reprod. 2008;23:217.

    Article  Google Scholar 

  30. Spandorfer S. Blastocyst frozen embryo transfer (FET): comparison of outcome with replacement in natural or programmed/medicated cycle. Fertil Steril. 2004;82:154.

    Article  Google Scholar 

  31. Azimi Nekoo E, Chamani M, Shahrokh Tehrani E, Hossein Rashidi B, Davari Tanha F, Kalantari V. Artificial endometrial preparation for frozen-thawed embryo transfer with or without pretreatment with depot gonadotropin releasing hormone agonist in women with regular menses. J Fam Reprod Health. 2015;9(1):1–4.

    Google Scholar 

  32. Kawamura T, Motoyama H, Yanaihara A, Yoramitsu TAA, Karasawa K, et al. Clinical outcomes of two different endometrial preparation methods for cryopreserved-thawed embryo transfer in patients with a normal menstrual cycle. Reprod Med Biol. 2007;6(1):53–7.

    Article  Google Scholar 

  33. Fatemi HM, Kyrou D, Bourgain C, Van den Abbeel E, Griesinger G, Devroey P. Cryopreserved-thawed human embryo transfer: spontaneous natural cycle is superior to human chorionic gonadotropin-induced natural cycle. Fertil Steril. 2010;94(6):2054–8. doi:10.1016/j.fertnstert.2009.11.036.

    Article  CAS  PubMed  Google Scholar 

  34. Weissman A, Horowitz E, Ravhon A, Steinfeld Z, Mutzafi R, Golan A, et al. Spontaneous ovulation versus HCG triggering for timing natural-cycle frozen-thawed embryo transfer: a randomized study. Reprod Biomed Online. 2011;23(4):484–9. doi:10.1016/j.rbmo.2011.06.004.

    Article  CAS  PubMed  Google Scholar 

  35. Chang EM, Han JE, Kim YS, Lyu SW, Lee WS, Yoon TK. Use of the natural cycle and vitrification thawed blastocyst transfer results in better in-vitro fertilization outcomes : cycle regimens of vitrification thawed blastocyst transfer. J Assist Reprod Genet. 2011;28(4):369–74. doi:10.1007/s10815-010-9530-4.

    Article  PubMed  PubMed Central  Google Scholar 

  36. Tomas C, Alsbjerg B, Martikainen H, Humaidan P. Pregnancy loss after frozen-embryo transfer—a comparison of three protocols. Fertil Steril. 2012;98(5):1165–9. doi:10.1016/j.fertnstert.2012.07.1058.

    Article  PubMed  Google Scholar 

  37. Weissman A, Levin D, Ravhon A, Eran H, Golan A, Levran D. What is the preferred method for timing natural cycle frozen-thawed embryo transfer? Reprod Biomed Online. 2009;19(1):66–71.

    Article  PubMed  Google Scholar 

  38. Levron J, Yerushalmi GM, Brengauz M, Gat I, Katorza E. Comparison between two protocols for thawed embryo transfer: natural cycle versus exogenous hormone replacement. Gynecol Endocrinol : Off J Int Soc Gynecol Endocrinol. 2014;30(7):494–7. doi:10.3109/09513590.2014.900032.

    Article  CAS  Google Scholar 

  39. Loh SK, Leong NK. Factors affecting success in an embryo cryopreservation programme. Ann Acad Med Singap. 1999;28(2):260–5.

    CAS  PubMed  Google Scholar 

  40. Morozov V, Ruman J, Kenigsberg D, Moodie G, Brenner S. Natural cycle cryo-thaw transfer may improve pregnancy outcome. J Assist Reprod Genet. 2007;24(4):119–23. doi:10.1007/s10815-006-9100-y.

    Article  PubMed  PubMed Central  Google Scholar 

  41. Orvieto R, Feldman N, Lantsberg D, Manela D, Zilberberg E, Haas J. Natural cycle frozen-thawed embryo transfer—can we improve cycle outcome? J Assist Reprod Genet. 2016;33(5):611–5. doi:10.1007/s10815-016-0685-5.

    Article  PubMed  Google Scholar 

  42. Veleva Z, Orava M, Nuojua-Huttunen S, Tapanainen JS, Martikainen H. Factors affecting the outcome of frozen-thawed embryo transfer. Hum Reprod. 2013;28(9):2425–31. doi:10.1093/humrep/det251.

    Article  PubMed  Google Scholar 

  43. Xiao Z, Zhou X, Xu W, Yang J, Xie Q. Natural cycle is superior to hormone replacement therapy cycle for vitrificated-preserved frozen-thawed embryo transfer. Syst Biol Reprod Med. 2012;58(2):107–12. doi:10.3109/19396368.2011.646047.

    Article  PubMed  Google Scholar 

  44. Mounce G, McVeigh E, Turner K, Child TJ. Randomized, controlled pilot trial of natural versus hormone replacement therapy cycles in frozen embryo replacement in vitro fertilization. Fertil Steril. 2015;104(4):915–20. doi:10.1016/j.fertnstert.2015.07.1131. e1.

    Article  CAS  PubMed  Google Scholar 

  45. Tanos V, Friedler S, Zajicek G, Neiger M, Lewin A, Schenker JG. The impact of endometrial preparation on implantation following cryopreserved-thawed-embryo transfer. Gynecol Obstet Investig. 1996;41(4):227–31.

    Article  CAS  Google Scholar 

  46. al-Shawaf T, Dave R, Harper J, Linehan D, Riley P, Craft I. Transfer of embryos into the uterus: how much do technical factors affect pregnancy rates? J Assist Reprod Genet. 1993;10(1):31–6.

    Article  CAS  PubMed  Google Scholar 

  47. Gelbaya TA, Nardo LG, Hunter HR, Fitzgerald CT, Horne G, Pease EE, et al. Cryopreserved-thawed embryo transfer in natural or down-regulated hormonally controlled cycles: a retrospective study. Fertil Steril. 2006;85(3):603–9. doi:10.1016/j.fertnstert.2005.09.015.

    Article  CAS  PubMed  Google Scholar 

  48. Hill MJ, Miller KA, Frattarelli JL. A GnRH agonist and exogenous hormone stimulation protocol has a higher live-birth rate than a natural endogenous hormone protocol for frozen-thawed blastocyst-stage embryo transfer cycles: an analysis of 1391 cycles. Fertil Steril. 2010;93(2):416–22. doi:10.1016/j.fertnstert.2008.11.027.

    Article  PubMed  Google Scholar 

  49. Queenan Jr JT, Veeck LL, Seltman HJ, Muasher SJ. Transfer of cryopreserved-thawed pre-embryos in a natural cycle or a programmed cycle with exogenous hormonal replacement yields similar pregnancy results. Fertil Steril. 1994;62(3):545–50.

    Article  PubMed  Google Scholar 

  50. Groenewoud ER, Cohlen BJ, Al-Oraiby A, Brinkhuis EA, Broekmans FJ, de Bruin JP, et al. A randomized controlled, non-inferiority trial of modified natural versus artificial cycle for cryo-thawed embryo transfer. Hum Reprod. 2016. doi:10.1093/humrep/dew120.

    PubMed  Google Scholar 

  51. Givens CR, Markun LC, Ryan IP, Chenette PE, Herbert CM, Schriock ED. Outcomes of natural cycles versus programmed cycles for 1677 frozen-thawed embryo transfers. Reprod Biomed Online. 2009;19(3):380–4.

    Article  PubMed  Google Scholar 

  52. Hancke K, More S, Kreienberg R, Weiss JM. Patients undergoing frozen-thawed embryo transfer have similar live birth rates in spontaneous and artificial cycles. J Assist Reprod Genet. 2012;29(5):403–7. doi:10.1007/s10815-012-9724-z.

    Article  PubMed  PubMed Central  Google Scholar 

  53. Konc J, Kanyo K, Varga E, Kriston R, Cseh S. The effect of cycle regimen used for endometrium preparation on the outcome of day 3 frozen embryo transfer cycle. Fertil Steril. 2010;94(2):767–8. doi:10.1016/j.fertnstert.2009.09.053.

    Article  PubMed  Google Scholar 

  54. Lathi RB, Chi YY, Liu J, Saravanabavanandhan B, Hegde A, Baker VL. Frozen blastocyst embryo transfer using a supplemented natural cycle protocol has a similar live birth rate compared to a programmed cycle protocol. J Assist Reprod Genet. 2015;32(7):1057–62. doi:10.1007/s10815-015-0499-x.

    Article  PubMed  PubMed Central  Google Scholar 

  55. El-Toukhy T, Taylor A, Khalaf Y, Al-Darazi K, Rowell P, Seed P, et al. Pituitary suppression in ultrasound-monitored frozen embryo replacement cycles. A randomised study. Hum Reprod. 2004;19(4):874–9. doi:10.1093/humrep/deh183.

    Article  CAS  PubMed  Google Scholar 

  56. Nekoo EA, Chamani M, Tehrani ES, Rashidi BH, Tanha FD, Kalantari V. Artificial endometrial preparation for frozen-thawed embryo transfer with or without pretreatment with depot gonadotropin releasing hormone agonist in women with regular menses. J Fam Reprod Health. 2014;9(1):1–4.

    Google Scholar 

  57. Simon A, Hurwitz A, Zentner BS, Bdolah Y, Laufer N. Transfer of frozen-thawed embryos in artificially prepared cycles with and without prior gonadotrophin-releasing hormone agonist suppression: a prospective randomized study. Hum Reprod. 1998;13(1O):2712–7.

    Article  CAS  PubMed  Google Scholar 

  58. Dor J, Rudak E, Davidson A, Levran D, Ben-Rafael Z, Mashiach S. Endocrine and biological factors influencing implantation of human embryos following cryopreservation. Gynecol Endocrinol : Off J Int Soc Gynecol Endocrinol. 1991;5(3):203–11.

    Article  CAS  Google Scholar 

  59. Imthurn B, Macas E, Rosselli M, Keller PJ. Effect of a programmed short-term stimulation protocol on the replacement of cryopreserved embryos. J Assist Reprod Genet. 1996;13(9):709–12.

    Article  CAS  PubMed  Google Scholar 

  60. Li SJ, Zhang YJ, Chai XS, Nie MF, Zhou YY, Chen JL, et al. Letrozole ovulation induction: an effective option in endometrial preparation for frozen-thawed embryo transfer. Arch Gynecol Obstet. 2014;289(3):687–93. doi:10.1007/s00404-013-3044-0.

    Article  CAS  PubMed  Google Scholar 

  61. Yu J, Ma Y, Wu Z, Li Y, Tang L, Li Y, et al. Endometrial preparation protocol of the frozen-thawed embryo transfer in patients with polycystic ovary syndrome. Arch Gynecol Obstet. 2015;291(1):201–11. doi:10.1007/s00404-014-3396-0.

    Article  CAS  PubMed  Google Scholar 

  62. Griesinger G, Weig M, Schroer A, Diedrich K, Kolibianakis EM. Mid-cycle serum levels of endogenous LH are not associated with the likelihood of pregnancy in artificial frozen-thawed embryo transfer cycles without pituitary suppression. Hum Reprod. 2007;22(10):2589–93. doi:10.1093/humrep/dem207.

    Article  CAS  PubMed  Google Scholar 

  63. Groenewoud ER, Kollen BJ, Macklon NS, Cohlen BJ. Spontaneous LH surges prior to HCG administration in unstimulated-cycle frozen-thawed embryo transfer do not influence pregnancy rates. Reprod Biomed Online. 2012;24(2):191–6. doi:10.1016/j.rbmo.2011.11.003.

    Article  CAS  PubMed  Google Scholar 

  64. Brosens J, Verhoeven H, Campo R, Gianaroli L, Gordts S, Hazekamp J, et al. High endometrial aromatase P450 mRNA expression is associated with poor IVF outcome. Hum Reprod. 2004;19(2):352–6.

    Article  CAS  PubMed  Google Scholar 

  65. Madero S, Rodriguez A, Vassena R, Vernaeve V. Endometrial preparation: effect of estrogen dose and administration route on reproductive outcomes in oocyte donation cycles with fresh embryo transfer. Hum Reprod. 2016. doi:10.1093/humrep/dew099.

    PubMed  Google Scholar 

  66. Remohi J, Vidal A, Pellicer A. Oocyte donation in low responders to conventional ovarian stimulation for in vitro fertilization. Fertil Steril. 1993;59(6):1208–15.

    Article  CAS  PubMed  Google Scholar 

  67. van der Linden M, Buckingham K, Farquhar C, Kremer JA, Metwally M. Luteal phase support for assisted reproduction cycles. Cochrane Database Syst Rev. 2015;7:CD009154. doi:10.1002/14651858.CD009154.pub3.

    PubMed  Google Scholar 

  68. Haddad G, Saguan DA, Maxwell R, Thomas MA. Intramuscular route of progesterone administration increases pregnancy rates during non-downregulated frozen embryo transfer cycles. J Assist Reprod Genet. 2007;24(10):467–70. doi:10.1007/s10815-007-9168-z.

    Article  PubMed  PubMed Central  Google Scholar 

  69. Kaser DJ, Ginsburg ES, Missmer SA, Correia KF, Racowsky C. Intramuscular progesterone versus 8% Crinone vaginal gel for luteal phase support for day 3 cryopreserved embryo transfer. Fertil Steril. 2012;98(6):1464–9. doi:10.1016/j.fertnstert.2012.08.007.

    Article  CAS  PubMed  Google Scholar 

  70. Wang Y, He Y, Zhao X, Ji X, Hong Y, Wang Y, et al. Crinone gel for luteal phase support in frozen-thawed embryo transfer cycles: a prospective randomized clinical trial in the Chinese population. PLoS One. 2015;10(7):e0133027. doi:10.1371/journal.pone.0133027.

    Article  PubMed  PubMed Central  Google Scholar 

  71. Shapiro DB, Pappadakis JA, Ellsworth NM, Hait HI, Nagy ZP. Progesterone replacement with vaginal gel versus i.m. injection: cycle and pregnancy outcomes in IVF patients receiving vitrified blastocysts. Hum Reprod. 2014;29(8):1706–11. doi:10.1093/humrep/deu121.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  72. Leonard PH, Hokenstad AN, Khan Z, Jensen JR, Stewart EA, Coddington CC. Progesterone support for frozen embryo transfer: intramuscular versus vaginal suppository demonstrates no difference in a cohort. J Reprod Med. 2015;60(3-4):103–8.

    PubMed  Google Scholar 

  73. El-Toukhy T, Coomarasamy A, Khairy M, Sunkara K, Seed P, Khalaf Y, et al. The relationship between endometrial thickness and outcome of medicated frozen embryo replacement cycles. Fertil Steril. 2008;89(4):832–9. doi:10.1016/j.fertnstert.2007.04.031.

    Article  PubMed  Google Scholar 

  74. Gingold JA, Lee JA, Rodriguez-Purata J, Whitehouse MC, Sandler B, Grunfeld L, et al. Endometrial pattern, but not endometrial thickness, affects implantation rates in euploid embryo transfers. Fertil Steril. 2015;104(3):620–8. doi:10.1016/j.fertnstert.2015.05.036. e5.

    Article  PubMed  PubMed Central  Google Scholar 

  75. Balaban B, Urman B, Ata B, Isiklar A, Larman MG, Hamilton R, et al. A randomized controlled study of human Day 3 embryo cryopreservation by slow freezing or vitrification: vitrification is associated with higher survival, metabolism and blastocyst formation. Hum Reprod. 2008;23(9):1976–82. doi:10.1093/humrep/den222.

    Article  CAS  PubMed  Google Scholar 

  76. Cercas R, Villas C, Pons I, Brana C, Fernandez-Shaw S. Vitrification can modify embryo cleavage stage after warming. Should we change endometrial preparation? J Assist Reprod Genet. 2012;29(12):1363–8. doi:10.1007/s10815-012-9881-0.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Hakan Yarali.

Additional information

Capsule

There is no consistent superiority of any endometrial preparation for FER.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yarali, H., Polat, M., Mumusoglu, S. et al. Preparation of endometrium for frozen embryo replacement cycles: a systematic review and meta-analysis. J Assist Reprod Genet 33, 1287–1304 (2016). https://doi.org/10.1007/s10815-016-0787-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10815-016-0787-0

Keywords

Navigation