The ART of frozen embryo transfer: back to nature!

Lawrenz, Barbara; Coughlan, Carol; Melado, Laura; Fatemi, Human M.

doi:10.1080/09513590.2020.1740918

Cited by 38 publications

(34 citation statements)

References 54 publications

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“…There are a number of recommendations regarding the management of cycles with frozen/thawed embryos, regarding endometrial preparation, progesterone supplementation, cycle monitoring, and implantation window assessment 52‐56 . Nonetheless, there is no agreement concerning the usefulness of delaying ET.…”

Section: Discussionmentioning

confidence: 99%

Meta‐analysis of the embryo freezing transfer interval

Matorras

Pijoán

Pérez-Ruiz

et al. 2021

Reprod Medicine & Biology

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Background The decision of whether frozen embryo transfer (FET) should be performed in the cycle immediately after OPU or at least one cycle later is controversial. FET could improve pregnancy rates in IVF; however, how much time is needed for the endometrium to return to optimal receptivity after ovarian stimulation is not known. Methods Electronic search in MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials to identify studies providing data on the influence of the interval between embryo freezing (or OPU) and FET in FET cycles published between January 1, 2007, and February 1, 2020. Main findings Data analyzed indicated that in the immediate FET cycles, there was a trend to an increased biochemical pregnancy rate (RR = 1.08; CI = 1.00‐1.18), whereas the clinical pregnancy rate was somewhat higher, but without reaching statistical significance (RR = 1.07; CI = 0.99‐1.15). The live birth rate was similar in the two groups (RR = 1.05; CI = 0.95‐1.15), as was the implantation rate (RR = 0.98; CI = 0.83‐1.16). Stratifying by embryo stage or FET type (freeze‐all or FET after failed fresh transfer) showed no differences. Conclusion Systematically delaying FET does not offer benefits to IVF outcomes. In addition, immediate transfer is associated with a nonsignificant trend to better clinical pregnancy rate and it also avoids the psychological effects of prolonging the stress on prospective parents.

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Section: Discussionmentioning

confidence: 99%

Meta‐analysis of the embryo freezing transfer interval

Matorras

Pijoán

Pérez-Ruiz

et al. 2021

Reprod Medicine & Biology

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“…There are different options described to prepare the endometrium for FET, including a natural cycle (NC-FET) based on the detection of the endogenous Luteinizing hormone (LH) surge in the blood, a modified natural cycle using human Chorion Gonadotropin (hCG) for final oocyte maturation, and artificial cycle (AC-FET) based on an hormonal replacement treatment with or without co-treatment with a Gonadotropin releasing hormone (GnRH) analog, and a stimulated cycle with antiestrogens, aromatase inhibitors or gonadotropins (Lawrenz et al, 2020). The most commonly used type of endometrial preparation is the AC-FET (Lawrenz et al, 2020), in which the administration of estrogens trying to mimic the changes generated by steroids of ovarian origin on the natural cycle. Endometrial thickness and pattern are monitored by vaginal ultrasound and progesterone administration is usually started from an endometrial thickness of approximately 7-8 mm (Liu et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Lower risk of adverse perinatal outcomes in natural versus artificial frozen–thawed embryo transfer cycles: a systematic review and meta-analysis

Moreno-Sepúlveda

Espinós

Checa

2021

Reproductive BioMedicine Online

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“…With all given increased maternal and obstetric risk factors, some authors suggested a "back to nature" attitude, advocating for more t-NC and modified-NC in future (194).…”

Section: Maternal and Obstetric Outcomes After Different Fet Protocolsmentioning

confidence: 99%

Preparation of the Endometrium for Frozen Embryo Transfer: A Systematic Review

et al. 2021

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Despite the worldwide increase in frozen embryo transfer, the search for the best protocol to prime endometrium continues. Well-designed trials comparing various frozen embryo transfer protocols in terms of live birth rates, maternal, obstetric and neonatal outcome are urgently required. Currently, low-quality evidence indicates that, natural cycle, either true natural cycle or modified natural cycle, is superior to hormone replacement treatment protocol. Regarding warmed blastocyst transfer and frozen embryo transfer timing, the evidence suggests the 6th day of progesterone start, LH surge+6 day and hCG+7 day in hormone replacement treatment, true natural cycle and modified natural cycle protocols, respectively. Time corrections, due to inter-personal differences in the window of implantation or day of vitrification (day 5 or 6), should be explored further. Recently available evidence clearly indicates that, in hormone replacement treatment and natural cycles, there might be marked inter-personal variation in serum progesterone levels with an impact on reproductive outcomes, despite the use of the same dose and route of progesterone administration. The place of progesterone rescue protocols in patients with low serum progesterone levels one day prior to warmed blastocyst transfer in hormone replacement treatment and natural cycles is likely to be intensively explored in near future.

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The ART of frozen embryo transfer: back to nature!

Cited by 38 publications

References 54 publications

Meta‐analysis of the embryo freezing transfer interval

Meta‐analysis of the embryo freezing transfer interval

Lower risk of adverse perinatal outcomes in natural versus artificial frozen–thawed embryo transfer cycles: a systematic review and meta-analysis

Preparation of the Endometrium for Frozen Embryo Transfer: A Systematic Review

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