Delayed versus immediate frozen embryo transfer after oocyte retrieval: a systematic review and meta-analysis

Huang, Jialyu; Lin, Jiaying; Lü, Xuefeng; Cai, Renfei; Song, Ning

doi:10.1007/s10815-020-01857-9

Cited by 10 publications

(7 citation statements)

References 36 publications

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“…In our study, an immediate FET did not improve nor worsen the clinical outcome, but it shortened the time patients wait to be pregnant successfully, which alleviated their anxiety compared with those in the postponed FET group. Our results were consistent with two recently published meta-analysis that did not find any association between the timing of FET and pregnancy outcomes ( 11 , 32 ).…”

Section: Discussionsupporting

confidence: 93%

“…However, another study favored delaying FET ( 10 ). Recently, several investigations found that the interval between oocyte pickup (OPU) and FET did not affect LBR ( 11 – 13 ). These conflicting results may be attributed to different study designs, complex confounding factors such as controlled ovarian hyperstimulation (COH) protocols, endometrial preparation regimes, ovarian response, etc.…”

Section: Introductionmentioning

confidence: 99%

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It is not worth postponing frozen embryo transfers after oocyte pickup: A retrospective cohort study based on propensity score matching

Jin

Guo

et al. 2022

Front. Endocrinol.

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This study was to explore whether postponing frozen embryo transfers (FET) after oocyte pickup (OPU) improves clinical and neonatal outcomes. From May 2018 to Dec 2020, a total of 1109 patients underwent their first OPU cycles adopting a non-selective freeze-all policy were included in this retrospective cohort study. In the immediate group (n=219), patients underwent FET in the first menstrual cycle after OPU, and patients in the postponed group (n=890) waited for more than 1 menstrual cycle after OPU to perform FET. A propensity score matching (PSM) model was used to evaluate the clinical outcomes and neonatal outcomes between the two groups. There were 209 patients in the immediate group and 499 patients in the postponed one after PSM. Patients waited for a significantly shorter period for FET in the immediate group (30.74 ± 3.85 days) compared with the postponed group (80.39 ± 26.25 days, P<0.01). The clinical pregnancy rate (CPR) and live birth rate (LBR) in the immediate group were 58.4% and 48.3%, respectively, which were comparable to those of the postponed one (58.1%, 49.7%, P > 0.05). No statistical significance was found in the average birth weight (3088.82 ± 565.35 g vs 3038.64 ± 625.78 g, P > 0.05) and height (49.08 ± 1.87 cm vs 49.30 ± 2.52 cm) of neonates between the two groups. The gender ratio, the incidence of macrosomia and low birth weight did not differ significantly between the two groups. In conclusion, postponing FET does not improve clinical and neonatal outcomes. If patients have no contraindications, FETs should be carried out immediately after OPU.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

It is not worth postponing frozen embryo transfers after oocyte pickup: A retrospective cohort study based on propensity score matching

Jin

Guo

et al. 2022

Front. Endocrinol.

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“…Lattes et al reported that there were no differences on the first FET and subsequent FET cycles after oocyte retrieval [ 23 ]. A retrospective study by Huang et al demonstrated that immediate FET was associated with a higher live birth than delayed FET [ 24 ], and meta-analysis indicated that immediate FET was not associated with negative pregnancy outcomes [ 25 ]. In our retrospective study, we only selected the HOR population who adopted HRT as the endometrial preparation protocol in the past five years and found no significant differences for CPR, SAR, and LBR between the immediate and delayed FET groups.…”

Section: Discussionmentioning

confidence: 99%

Effects of immediate versus delayed frozen embryo transfer in high responder patients undergoing freeze-all cycles

Zuo

Gao

et al. 2021

BMC Pregnancy Childbirth

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Background Frozen embryo transfer (FET) can greatly improve the pregnancy outcomes for high responder patients. However, it is not known whether the timing of FET is a risk factor on pregnancy outcomes in high responder patients undergoing freeze-all cycles. Methods A retrospective cohort study to compare the pregnancy outcomes of the immediate and delayed FET groups in high responder patients undergoing freeze-all cycles. The two groups were defined as that FET took place either within the first menstrual cycle following oocyte retrieval or afterwards. Propensity score matching was used to make the potential risk factors of the two groups comparable. Multivariable regression analysis was used to study the effect of the timing of FET on pregnancy outcomes in the entire cohort and propensity score-matched cohort, even in different controlled ovarian hyperstimulation protocol cohorts as subgroup analysis. Results We obtained 1130 patients in immediate FET group and 998 patients in delayed FET group, and the average age of the two groups were 30.30 and 30.63. We showed that the immediate FET group were equivalent to delayed FET group in the entire cohort [clinical pregnancy rate (CPR), 61.0% versus 63.4%, adjusted odd ratio (OR), 0.939, 95% confidence interval (CI), 0.781–1.129; spontaneous abortion rate (SAR), 10.1% versus 12.6%, adjusted OR, 0.831, 95% Cl (0.628–1.098); live birth rate (LBR), 49.9% versus 49.2%, adjusted OR, 1.056, 95% Cl (0.883–1.263)]. The same results were obtained by χ2 test in the propensity score-matched cohort (CPR, 60.5% versus 63.5%; SAR, 11.6% versus 12.3%; LBR, 48% versus 49.3%) (P > 0.05). Subgroup analysis indicated that pregnancy outcomes of immediate FET were no difference to delayed FET in gonadotropin-releasing hormone agonist (GnRH-a) protocol (P > 0.05). The SAR of the immediate FET group were lower than that of the delayed FET group in GnRH antagonist protocol (adjusted OR, 0.645, 95% CI, 0.430–0.966) (P < 0.05), no differences were observed in CPR and LBR (P > 0.05). Conclusions The pregnancy outcomes of immediate FET were no difference to delayed FET in high responder population undergoing freeze-all cycles.

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“…The reviews are based on retrospective data including a variety of FET protocols, hence, the presence of selection bias is apparent and the quality of evidence is low. Despite a significant overlap in studies included in the reviews, the results differ slightly, probably due to inclusion of unadjusted 14 versus adjusted 15 results. Huang et al reported no significant association between timing of FET and pregnancy outcomes; clinical pregnancy rate (CPR) (relative risk (RR) 0.94 (95% CI 0.87 to 1.03)) and live birth rate (LBR) (RR 0.94 (95% CI 0.85 to 1.03)) while Bergenheim et al found a slightly higher CPR (adjusted OR (aOR) 1.22 (95% CI 1.07 to 1.39)) and LBR (aOR 1.20 (95% CI 1.01 to 1.44)) in immediate versus postponed FET.…”

Section: Introductionmentioning

confidence: 92%

Immediate versus postponed single blastocyst transfer in modified natural cycle frozen embryo transfer (mNC-FET): a study protocol for a multicentre randomised controlled trial

et al. 2021

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Introduction Today, it is widespread practice to postpone frozen embryo transfer (FET) in a modified natural cycle (mNC) for at least one menstrual cycle after oocyte retrieval and failed fresh embryo transfer or freeze-all. The rationale behind this practice is the concern that suboptimal ovarian, endometrial or endocrinological conditions following ovarian stimulation may have a negative impact on endometrial receptivity and implantation. However, two recent systematic reviews and meta-analyses based on retrospective data did not support this practice. As unnecessary delay in time to transfer and pregnancy should be avoided, the aim of this study is to investigate if immediate single blastocyst transfer in mNC-FET is non-inferior to standard postponed single blastocyst transfer in mNC-FET in terms of live birth rate. Methods and analysis Multicentre randomised controlled non-blinded trial including 464 normo-ovulatory women aged 18–40 years undergoing single blastocyst mNC-FET after a failed fresh or freeze-all cycle. Participants are randomised 1:1 to either FET in the first menstrual cycle following the stimulated cycle (immediate FET) or FET in the second or subsequent cycle following the stimulated cycle (postponed FET). The study is designed as a non-inferiority trial and primary analyses will be performed as intention to treat and per protocol. Ethics and dissemination Ethical approval has been granted by the Scientific Ethical Committee of the Capital Region of Denmark (J-nr.: H-19086300). Data will be handled according to Danish law on personal data protection in accordance with the general data protection regulation. Participants will complete written consent forms regarding participation in the study and storage of blood samples in a biobank for future research. The study will be monitored by a Good Clinical Practice (GCP)-trained study nurse not otherwise involved in the study. The results of this study will be disseminated by publication in international peer-reviewed scientific journals. Trial registration number NCT04748874; Pre-results.

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Delayed versus immediate frozen embryo transfer after oocyte retrieval: a systematic review and meta-analysis

Cited by 10 publications

References 36 publications

It is not worth postponing frozen embryo transfers after oocyte pickup: A retrospective cohort study based on propensity score matching

It is not worth postponing frozen embryo transfers after oocyte pickup: A retrospective cohort study based on propensity score matching

Effects of immediate versus delayed frozen embryo transfer in high responder patients undergoing freeze-all cycles

Immediate versus postponed single blastocyst transfer in modified natural cycle frozen embryo transfer (mNC-FET): a study protocol for a multicentre randomised controlled trial

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