Acknowledgements
The authors thank the staff from Northwest Women’s and Children’s Hospital for their assistance with the data collection.
R eferences
  1. Zhu, D, Zhang J, Cao S, et al. Vitrified-warmed blastocyst transfer cycles yield higher pregnancy and implantation rates compared with fresh blastocyst transfer cycles–time for a new embryo transfer strategy? Fertil Steril. 2011; 95(5): p. 1691-5.
  2. Loutradi, K.E, Kolibianakis EM, Venetis CA, et al. Cryopreservation of human embryos by vitrification or slow freezing: a systematic review and meta-analysis. Fertil Steril. 2008; 90(1): p. 186-93.
  3. Belva, F, Bonduelle M, Roelants M, et al. Neonatal health including congenital malformation risk of 1072 children born after vitrified embryo transfer. Hum Reprod. 2016; 31(7): p. 1610-20.
  4. Ghobara T, Gelbaya TA, Ayeleke RO. Cycle regimens for frozen-thawed embryo transfer. The Cochrane database of systematic reviews. 2017; 7(7): Cd003414.
  5. Lathi, R.B, Chi YY, et al. 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): p. 1057-62.
  6. Agha-Hosseini, M, Hashemi L, Aleyasin A, et al. Natural cycle versus artificial cycle in frozen-thawed embryo transfer: A randomized prospective trial. Turk J Obstet Gynecol. 2018; 15(1): p. 12-17.
  7. Jing, S, Li XF, Zhang S, et al. Increased pregnancy complications following frozen-thawed embryo transfer during an artificial cycle. J Assist Reprod Genet. 2019; 36(5): p. 925-933.
  8. Zhao J, Zhang Q, Wang Y, et al. Endometrial pattern, thickness and growth in predicting pregnancy outcome following 3319 ivf cycle. Reproductive biomedicine online 2014; 29(3): 291-298.
  9. Zegers-Hochschild, F, Adamson GD, Dyer S, et al. The International Glossary on Infertility and Fertility Care, 2017. Hum Reprod 2017; 32(9): p. 1786-1801.
  10. American College of O, Gynecologists’ Committee on Practice BO. Practice Bulletin No. 171: Management of Preterm Labor. Obstet Gynecol 2016; 128(10): e155-e164.
  11. Gelbaya TA, Nardo LG, Hunter HR, et al. Cryopreserved-thawed embryo transfer in natural or down-regulated hormonally controlled cycles: a retrospective study. Fertility and sterility. 2006;85(3):603–9.
  12. Hancke K, More S, Kreienberg R, et al. Patients undergoing frozen-thawed embryo transfer have similar live birth rates in spontaneous and artificial cycles. J Assist Reprod Genet. 2012;29(5):403–407.
  13. Tomas C, Alsbjerg B, Martikainen H, et al. Pregnancy loss after frozen-embryo transfer–a comparison of three protocols. Fertility and sterility 2012;98(5):1165–1169.
  14. HillMJ, 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. Fertility and sterility. 2010;93(2):416–422.
  15. Zheng Y, Li Z, XiongM, et al. Hormonal replacement treatment improves clinical pregnancy in frozen thawed embryos transfer cycles: a retrospective cohort study. Am J Transl Res 2014;6(1):85–90.
  16. Cerrillo M, Herrero L, Guillen A, et al. Impact of endometrial preparation protocols for frozen embryo transfer on live birth rates. Rambam Maimonides medical journal. 2017; 8(2): e0020.
  17. Givens CR, Markun LC, Ryan IP, et al. Outcomes of natural cycles versus programmed cycles for 1677 frozen-thawed embryo transfers. Reproductive biomedicine online. 2009; 19(3): 380-384.
  18. Lyall F, Robson SC, Bulmer JN. Spiral artery remodeling and trophoblast invasion in preeclampsia and fetal growth restriction: relationship to clinical outcome. Hypertension 2013; 62(6): p. 1046-54.
  19. Hiura H, Hattori H, Kobayashi N, et al. Genome-wide microRNA expression profiling in placentae from frozen-thawed blastocyst transfer. Clin Epigenetics. 2017; 9(3): p. 79.
  20. Rizzo, G, Aiello E, Pietrolucci ME, et al. Are There Differences in Placental Volume and Uterine Artery Doppler in Pregnancies Resulting From the Transfer of Fresh Versus Frozen-Thawed Embryos Through In Vitro Fertilization. Reprod Sci. 2016; 23(10): p. 1381-6.
  21. Fritz R, Jindal S, Feil H, et al. Elevated serum estradiol levels in artificial autologous frozen embryo transfer cycles negatively impact ongoing pregnancy and live birth rates. J Assist Reprod Genet. 2017; 34(12): 1633-1638.
  22. Patel S, Kilburn B, Imudia A, et al. Estradiol elicits proapoptotic and antiproliferative effects in human trophoblast cells. Biol Reprod. 2015; 93(3): 74.
  23. Shavit T, Oron G, Weon-Young S, et al. Vitrified-warmed single-embryo transfers may be associated with increased maternal complications compared with fresh single-embryo transfers. Reprod Biomed Online. 2017;35(1):94-102.
  24. Sites CK, Wilson D, Barsky M, et al. Embryo cryopreservation and preeclampsia risk. Fertility and sterility. 2017; 108(5): 784-790.
Table 1. Baseline characteristics between different endometrial preparation groups