The freeze-all strategy after IVF: which indications?

The "freeze-all" strategy seems to improve the chances of birth in adenomyosis-affected women

OBJECTIVE

To compare assisted reproductive technologies (ARTs) outcomes between fresh vs. freeze-all strategies in infertile women affected by adenomyosis.

DESIGN

A single-center observational study.

SETTINGS

University hospital-based research center.

PATIENTS

Adenomyosis-affected women undergoing blastocyst embryo transfer after in vitro fertilization and intracytoplasmic sperm injection between January 1, 2018, and November 31, 2021. The diagnosis of adenomyosis was based on imaging criteria (i.e., transvaginal ultrasound and/or magnetic resonance imaging).

INTERVENTION(S)

Women who underwent a freeze-all strategy were compared with those who underwent a fresh embryo transfer (ET) strategy.

MAIN OUTCOME MEASURE(S)

Cumulative live birth rate (LBR).

RESULTS

A total of 306 women were included in the analysis: 111 in the fresh ET group and 195 in the freeze-all group. The adenomyosis phenotype (internal diffuse adenomyosis, external focal adenomyosis, and adenomyoma) was not significantly different between the two groups. The cumulative LBR (86 [44.1%] vs. 34 [30.6%], respectively), and the cumulative ongoing pregnancy rate (88 [45.1%] vs. 36 [32.4%], respectively) were significantly higher in the freeze-all group compared with the fresh ET group. After multivariate logistic regression analysis, the freeze-all strategy in women with adenomyosis was associated with significantly higher odds of live birth compared with fresh ET (odds ratio = 1.80; 95% confidence interval = 1.02-3.16).

CONCLUSION

The freeze-all strategy in women afflicted with adenomyosis undergoing ART was associated with significantly higher cumulative LBRs. Our preliminary results suggest that the freeze-all strategy is an attractive option that increases ART success rates. Additional studies, with a randomized design, should be conducted to further test whether the freeze-all strategy enhances the pregnancy rate in adenomyosis-affected women.

PGT and deferred embryo transfer: Is blastocyst biopsy more effective than cleaved embryo biopsy?

OBJECTIVE

Blastocyst biopsy has recently been implemented in our laboratory for PGT with a "freeze all" indication. The aim of this study is to compare PGT results between embryos biopsied at the cleaved and embryos biopsied at the blastocyst stage.

STUDY DESIGN

This is a retrospective cohort study conducted from January 2017 to December 2022 in France. All couples with a "freeze all" indication the day of hCG trigerring during the study period were included in the study. Patients were retrospectively assigned in one group of two groups based on the day of embryo biopsy: the cleavage group if a blastomere biopsy was performed on day 3/4 or the blastocyst group if a trophectoderm biopsy was performed on day 5/6. We evaluated and compared the results between the two groups for biological parameters and clinical outcomes.

RESULTS

In total, 325 PGT cycles (291 patients) were included in our study. Frozen-thawed embryo transfer was performed for 285 cycles, 122 in the blastocyst group and 163 in the cleavage group. The number of biopsied embryos per cycle is significantly higher in the cleavage group with a mean of 7.2 ± 4.1 embryos biopsied per cycle vs. 2.9 ± 2.8 embryos in the blastocyst group (p < 0.001). The rate of the useful embryos was similar between the two groups with 14.6 % of frozen healthy embryos among the 1352 cleaved embryos obtained in blastocyst group, compared to 17.1 % in the cleavage group. No significant differences in clinical pregnancy rate per transfer and implantation rate were observed between the blastocyst and cleavage groups (36.4% vs. 40.4 % and 33.1% vs. 33.2 % respectively).

CONCLUSIONS

For "freeze all" PGT cycles, the day of embryo biopsy (cleaved vs blastocyst biopsy) does not impact pregnancy outcomes. Knowing how to perform embryo biopsy at different stages helps to better organize daily laboratory activity and to rescue some undiagnosed embryos after day 3 biopsy.

Endometriosis-related infertility: severe pain symptoms do not impact assisted reproductive technology outcomes

STUDY QUESTION

Do severe endometriosis-related painful symptoms impact ART live birth rates?

SUMMARY ANSWER

Severe pain symptoms are not associated with reduced ART live birth rates in endometriosis patients.

WHAT IS KNOWN ALREADY

ART is currently recognized as one of the main therapeutic options to manage endometriosis-related infertility. Presently, no data exist in the literature regarding the association between the core symptom of the disease, e.g. pain and ART reproductive outcomes.

STUDY DESIGN, SIZE, DURATION

Observational cohort study of 354 endometriosis patients, who underwent ART at a tertiary care university hospital, between October 2014 and October 2021. Diagnosis of endometriosis was based on published imaging criteria using transvaginal sonography and magnetic resonance imaging, and histologically confirmed in women who had a previous history of endometriosis surgery (n = 127, 35.9%).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The intensity of painful symptoms related to dysmenorrhea (DM), dyspareunia (DP), noncyclic chronic pelvic pain, gastrointestinal (GI) pain, or lower urinary tract pain was evaluated using a 10-point visual analog scale (VAS), before ART. Severe pain was defined as having a VAS of 7 or higher for at least one symptom. The main outcome measure was the cumulative live birth rate (CLBR) per patient. We analyzed the impact of endometriosis-related painful symptoms on ART live births using univariable and multivariate analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Three hundred and fifty-four endometriosis patients underwent 711 ART cycles. The mean age of the population was 33.8 ± 3.7 years, and the mean duration of infertility was 3.6 ± 2.1 years. The distribution of the endometriosis phenotypes was 3.1% superficial endometriosis, 8.2% ovarian endometrioma, and 88.7% deep infiltrating endometriosis. The mean VAS scores for DM, DP, and GI pain symptoms were 6.6 ± 2.7, 3.4 ± 3.1, and 3.1 ± 3.6, respectively. Two hundred and forty-two patients (68.4%) had severe pain symptoms. The CLBR per patient was 63.8% (226/354). Neither the mean VAS scores for the various painful symptoms nor the proportion of patients displaying severe pain differed significantly between patients who had a live birth and those who had not, based on univariate and multivariate analyses (P = 0.229). The only significant factors associated with negative ART live births were age >35 years (P < 0.001) and anti-Müllerian hormone levels <1.2 ng/ml (P < 0.001).

LIMITATIONS, REASONS FOR CAUTION

The diagnosis of endometriosis was based on imaging rather than surgery. This limitation is, however, inherent to the design of most studies on endometriosis patients reverting to ART first.

WIDER IMPLICATIONS OF THE FINDINGS

Rather than considering a single argument such as pain, the decision-making process for choosing between ART and surgery in infertile endometriosis patients should be based on a multitude of aspects, including the patient's choice, the associated infertility factors, the endometriosis phenotypes, and the efficiency of medical therapies in regard to pain symptoms, through an individualized approach guided by a multidisciplinary team of experts.

STUDY FUNDING/COMPETING INTEREST(S)

No funding; no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Assisted Reproductive Technology in the Presence of Polycystic Ovary Syndrome: Current Evidence and Knowledge Gaps

OBJECTIVE

In this narrative review, we discuss the current evidence as well as the knowledge gaps concerning assisted reproductive technology (ART) indications, protocols, and results in the presence of polycystic ovary syndrome (PCOS).

METHODS

An electronic literature search was performed for English-language publications in the last decade in databases such as PubMed, Medline, the Web of Sciences, Embase, and Scopus.

RESULTS

We found evidence that ovarian steroidogenesis and folliculogenesis are deeply altered by PCOS; however, the oocyte quality and pregnancy rates after ART are not affected. Patients with PCOS are more sensitive to the action of exogenous gonadotropins and more likely to develop ovarian hyperstimulation syndrome. This risk can be mitigated by the adoption of the gonadotropin-releasing hormone antagonist protocols for pituitary blockade and ovarian stimulation, along with frozen embryo transfer, without compromising the odds of achieving a live birth. Pregnancy complications, such as miscarriage, gestational diabetes, preeclampsia, and very preterm birth, are more frequent in the presence of PCOS, requiring more intense prenatal care. It remains uncertain whether weight reduction or insulin sensitizers used before ART are beneficial for the treatment outcomes.

CONCLUSION

Although PCOS is not a drawback for ART treatments, the patients need special care to avoid complications. More in-depth studies are needed to uncover the mechanisms of follicular growth, gamete maturation, and endometrial differentiation during ART procedures in the presence of PCOS.

Development and validation of a nomogram for predicting ongoing pregnancy in single vitrified-warmed blastocyst embryo transfer cycles

Introduction

The global adoption of the "freeze-all strategy" has led to a continuous increase in utilization of single vitrified-warmed blastocyst embryo transfer (SVBT) owing to its clinical effectiveness. Accurate prediction of clinical pregnancy is crucial from a patient-centered perspective. However, this remains challenging, with inherent limitations due to the absence of precise and user-friendly prediction tools. Thus, this study primarily aimed to develop and assess a nomogram based on quantitative clinical data to optimize the efficacy of personalized prognosis assessment.

Materials and methods

We conducted a retrospective cohort analysis of ongoing pregnancy data from 658 patients with infertility who underwent SVBT at our center between October 17, 2017, and December 18, 2021. Patients were randomly assigned to the training (n=461) or validation (n=197) cohort for nomogram development and testing, respectively. A nomogram was constructed using the results of the multivariable logistic regression (MLR), which included clinical covariates that were assessed for their association with ongoing pregnancy.

Results

The MLR identified eight significant variables that independently predicted ongoing pregnancy outcomes in the study population. These predictors encompassed maternal physiology, including maternal age at oocyte retrieval and serum anti-Müllerian hormone levels; uterine factors, such as adenomyosis; and various embryo assessment parameters, including the number of fertilized embryos, blastocyst morphology, blastulation day, blastocyst re-expansion speed, and presence of embryo string. The area under the receiver operating characteristic curve in our prediction model was 0.675 (95% confidence interval [CI], 0.622-0.729) and 0.656 (95% CI, 0.573-0.739) in the training and validation cohorts, respectively, indicating good discrimination performance in both cohorts.

Conclusions

Our individualized nomogram is a practical and user-friendly tool that can provide accurate and useful SVBT information for patients and clinicians. By offering this model to patients, clinical stakeholders can alleviate uncertainty and confusion about fertility treatment options and enhance patients' confidence in making informed decisions.

Oocyte Cryopreservation in Women with Ovarian Endometriosis

Ovarian endometriosis is a gynecological condition that is closely associated with infertility-from its pathogenesis to treatment modalities, this condition presents a challenge both for patients and clinicians alike when seeking conception, due to low AMH levels, peritoneal inflammation, and the inadvertent removal of healthy ovarian parenchyma at surgery. In fact, around half of endometriosis patients seeking fertility require tertiary-level assisted reproduction techniques to achieve a live birth. Oocyte cryopreservation, a procedure initially designed for oncology patients, has emerged over recent years as a very promising treatment strategy for patients who have been diagnosed with ovarian endometriosis in order to preserve their fertility and obtain a live birth at a later stage in their lives. Counseling patients about oocyte preservation techniques at an early stage in the diagnosis, ideally before the age of 35 and especially prior to any surgical treatment, provides an excellent opportunity to discuss future fertility and the benefits associated with oocyte cryopreservation.

The destinies of human embryos reaching blastocyst stage between Day 4 and Day 7 diverge as early as fertilization

STUDY QUESTION

What clinical and laboratory differences emerge from parallel direct comparison of embryos reaching the blastocyst stage between Days 4, 5, 6, and 7 (Days 4-7)?

SUMMARY ANSWER

Increasing times to blastocyst formation are associated with a worse clinical outcome and perturbations in developmental patterns appear as early as the fertilization stage.

WHAT IS KNOWN ALREADY

Previous evidence indicates that later times to blastocyst development are associated with a worse clinical outcome. However, the vast majority of these data concern Day 5 and Day 6 blastocysts, while Day 4 and Day 7 blastocysts remain less thoroughly investigated. In addition, studies comparing in parallel the developmental patterns and trajectories of Day 4-7 blastocysts are lacking. This leaves unanswered the question of when and how differences among such embryos emerge. Acquisition of such knowledge would significantly contribute to understanding the relative impact of intrinsic and extrinsic causes of embryo developmental kinetics and competence.

STUDY DESIGN, SIZE, DURATION

This retrospective study involved time-lapse technology (TLT) monitoring of Day 4 (N = 70), Day 5 (N = 6147), Day 6 (N = 3243), and Day 7 (N = 149) blastocysts generated in 9450 ICSI cycles. Oocyte retrievals were carried out after clomiphene citrate-based minimal ovarian stimulation, between January 2020 and April 2021.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Couples included in the study presented with different diagnoses, mainly male factor and unexplained infertility. Cases involving cryopreserved gametes or surgically retrieved sperm were excluded. Microinjected oocytes were assessed by a combined TLT-culture system. Day 4-7 blastocyst groups were compared in terms of morphokinetics (pronuclear dynamics, cleavage patterns and timings, and embryo quality) and clinical outcome. Clinically usable blastocysts were cryopreserved and transferred in single vitrified-warmed blastocyst transfers (SVBT).

MAIN RESULTS AND THE ROLE OF CHANCE

From 19 846 microinjected oocytes, 17 144 zygotes (86.4%) were obtained. Overall, the blastocyst development rate was 56.0%. Rates of blastocysts formation on Days 4, 5, 6, and 7 were 0.7%, 64.0%, 33.8%, and 1.6%, respectively. The average expanded blastocyst development times were 98.4 ± 0.4, 112.4 ± 0.1, 131.6 ± 0.1, and 151.2 ± 0.5 h in the Day 4-7 groups, respectively. Female age was positively associated with longer times to blastocyst development. Rates of both inner cell mass (ICM) and trophectoderm (TE) morphological grade A blastocysts were negatively associated with the day of blastocyst development (P < 0.0001). The differences in development times and intervals increased progressively until blastocyst expansion (P < 0.0001 for all development times). Strikingly, such differences were already markedly evident as early as the time of pronuclear fading (tPNf) (20.6 ± 0.3, 22.5 ± 0.0, 24.0 ± 0.0, 25.5 ± 0.3; Days 4-7, respectively; P < 0.0001). Rates of cleavage anomalies (tri-/multi-chotomous mitosis or rapid cleavage) occurring at the first or second/third division cycles were also positively associated with longer times to blastocyst development. Implantation, ongoing pregnancy, and live birth rates were progressively reduced with increasing blastocyst development times (P < 0.0001), even after stratification for maternal age. When controlled for female age, male age, number of previous embryo transfer cycles, morphological grade of the ICM and TE, and progesterone supplementation, the probabilities of implantation, clinical, and ongoing pregnancy and live birth were significantly decreased in Day 6 blastocysts in comparison to Day 5 blastocysts. Follow-up data on birth length, weight, and malformations were comparable among the four blastocyst groups.

LIMITATIONS, REASONS FOR CAUTION

The study is limited by its retrospective design. Having been obtained from a single centre, the data require independent validation.

WIDER IMPLICATIONS OF THE FINDINGS

This study extends previous data on the relation between time of blastocyst formation and clinical outcome. It also indicates that differences in developmental times and patterns of Day 4-7 blastocysts occur as early as the fertilization stage, possibly dictated by intrinsic gamete-derived factors.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the participating institutions. The authors have no conflict of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

IVF/ICSI Outcomes After a Freeze-All Strategy: an Observational Cohort Study

In order to inform patients undergoing ART regarding their chances for motherhood, it seems useful to describe "freeze all" outcomes according to the different potential indications. The goal of this study was to examine the impact of a "freeze-all approach" on the cumulative live birth rate (cLBR) according to the indication. It is a cohort study including women who had undergone ovarian stimulation (OS) using an antagonist protocol with GnRH agonist triggering between 09.2016 and 09.2018 followed by a freeze-all cycle of blastocyst embryos. The ART outcomes were compared between the two main indications of the freeze-all strategy which were in our cohort: risk of ovarian hyperstimulation syndrome (OHSS) and endometriosis. The ART outcomes were also described for the others indications (inadequate endometrium and/or premature progesterone elevation at trigger day, two or more previous ART failures, and autoimmune disease and/or a high risk of thromboembolic disease (AI and/or TE risk)). In total, 658 women were included. The cLBR in the total population was 37.7% (248/658). The cLBR was significantly higher in the "OHSS risk" group (133/281, 47.3%) than in the "endometriosis" group (69/190, 36.3%) (p = 0.017). No significant differences were noted regarding perinatal outcomes, except a significantly higher risk of placenta praevia (PP) observed in the "endometriosis" group (10.1%) (p = 0.002). The "freeze-all approach" yielded good results in terms of the cLBR and especially in case of OHSS risk. These data should be taken into account when informing patients about the ART strategy and their chances of motherhood.

Ovulatory-cycle frozen embryo transfer: spontaneous or triggered ovulation and the impact of LH elevation at hCG triggering

The effect of the luteinizing hormone (LH) elevation before the human chorionic gonadotropin (hCG) trigger in ovulatory frozen-thawed embryo transfer (Ovu-FET) cycles has not been determined. We aimed to investigate whether triggering ovulation in Ovu-FET cycles affects the live birth rate (LBR), and the contribution of elevated LH at the time of hCG trigger. This retrospective study included Ovu-FET cycles performed in our center from August 2016 to April 2021. Modified Ovu-FET (hCG trigger) and true Ovu-FET (without hCG trigger) were compared. The modified group was divided according to whether hCG was administered, before or after LH increased to > 15 IU/L and was twice the baseline value. The modified (n = 100) and true (n = 246) Ovu-FET groups and both subgroups of the modified Ovu-FET, those who were triggered before (n = 67) or after (n = 33) LH elevation, had comparable characteristics at baseline. Comparison of true vs. modified Ovu-FET outcomes revealed similar LBR (35.4% vs. 32.0%; P = 0.62), respectively. LBR were similar between the modified Ovu-FET subgroups regardless of the hCG trigger timing (31.3% before vs. 33.3% after LH elevation; P = 0.84). In conclusion, LBR of Ovu-FET were not affected by hCG trigger or whether LH was elevated at the time of hCG trigger. These results add reassurance regarding hCG triggering even after LH elevation.

Effectiveness of progesterone rescue in women presenting low circulating progesterone levels around the day of embryo transfer: a systematic review and meta-analysis

IMPORTANCE

Over the last decade, frozen embryo transfer (FET) has been increasingly used in contemporary fertility units. Despite the rapid increase in FET, there is still insufficient evidence to recommend an optimized protocol for endometrial preparation especially in patients with lower progesterone (P4) levels. Previous studies have concluded that P4 levels <10 ng/mL are associated with poorer pregnancy outcomes than those reported with high levels of circulating P4.

OBJECTIVE

To identify whether rescue P4 dosing in patients with low P4 can salvage adverse outcomes associated with low P4 levels, resulting in outcomes comparable to patients with adequate progesterone.

DATA SOURCES

The study was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-analyses guidelines and prospectively registered under the PROSPERO database (CRD42022357125). Six databases (Embase, MEDLINE, APA PsycInfo, Global Health, HMIC Health Management Information Consortium, and Google Scholar) and 2 additional sources were searched from inception to August 29, 2022.

STUDY SELECTION AND SYNTHESIS

Prospective and retrospective cohort studies, reporting the association between rescue progesterone and one or more pregnancy outcomes, were included. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS), while the quality of evidence by the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. Summative and subgroup data as well as heterogeneity were generated by the Cochrane platform RevMan (V. 5.4).

MAIN OUTCOME MEASURE(S)

To compare ongoing pregnancy rate as primary outcome and clinical pregnancy rate, miscarriage rate, and live birth rate as secondary outcomes between patients with low (<10 ng/mL) receiving rescue progesterone vs. those with adequate levels of P4 (≥10 ng/mL).

RESULT(S)

Overall, 7 observational studies were included in the analysis, with a total of 5927 patients of median age 34 (interquartile range [IQR]: 31.55, 37.13). Overall, patient group comparison, namely those with low P4 that received a rescue dose and those with adequate P4 levels, did not yield significant differences for either the primary or secondary outcomes. For ongoing clinical pregnancy, patients with low P4 receiving the rescue dose vs. those with adequate P4 levels was odds ratio (OR) 0.98 (95% CI: 0.78, 1.24; P = .86, I²: 41%), whereas for miscarriage events, OR was 0.98 (95% CI: 0.81, 1.17; P = .80, I²: 0). Equally, for clinical pregnancy, OR was 0.91 (95% CI: 0.78, 1.06; P = .24; I²: 33%), and for live birth, OR was 0.92 (95% CI: 0.77, 1.09; P = .33; I²: 43%). Subgroup analysis on the basis or rescue administration route successfully explained summative heterogeneity.

CONCLUSION(S)

Rescue P4 dosing in patients with low P4 results in ongoing pregnancy rate, clinical pregnancy and live birth rates were comparable to those of patients with adequate P4 levels. However, robust randomized controlled trials assessing rescue treatment in women with low P4 are needed to confirm these findings. Rescue P4 in patients with low circulating P4 around embryo transfer day may result in reproductive outcomes comparable to those with adequate P4 levels.

STUDY REGISTRATION

CRD42022357125 (PROSPERO).

Which sperm parameter limits could really guide the clinical decision in assisted reproduction?

BACKGROUND

The predictive role of sperm motility and morphology was recently detected in a large sample of more than 20000 assisted reproductive technology (ART) fresh cycles. However, the complete ART procedure consisted of both fresh and frozen-embryos transfers and only a comprehensive evaluation of the entire process could really confirm if these parameters really predict the ART success. The aim of the study was to evaluate which sperm parameter could predict the success of ART.

METHODS

A retrospective, real-world data analysis was performed, enrolling all couples attending ART from 2008 to 2021, including both fresh and frozen cycles and both in vitro fertilization (IVF) and intra-cytoplasmic sperm injection (ICSI) procedures.

RESULTS

Fresh cycles success (considering live birth rate) was predicted by female age (1.04 [1.02-1.06]), injected oocytes (0.96 [0.93-0.99]), embryo number (0.79 [0.75-0.83]) and progressive sperm motility (0.98 [0.97-0.99]). On the contrary, frozen cycle outcomes were predicted only by sperm motility (0.97 [0.95-0.99]). This prediction was confirmed in IVF but not in ICSI cycles.

CONCLUSION

Both female and male parameters predicted the ART success considering the entire path. However, frozen cycle success was predicted only by progressive sperm motility in IVF cycles, suggesting that the potential amelioration of this male parameter is relevant to improve ART success. Those couples expected to obtain the highest embryos after fertilization (low female age and better semen parameters) will have more attempts with frozen cycles and thus would benefit from a potential treatment focused to improve sperm parameters.

Post-Thaw Day 5 Blastocyst Culture Time Prior to Transfer Does Not Affect Assisted Reproduction Technology (ART) Outcomes in Frozen-Thawed Embryo Transfer Cycles

The frozen embryo transfer (FET) technique has been progressively used more worldwide due to improved culture conditions, as well as enhanced survival rates after vitrification. However, little is known about the effect of the post-thaw blastocyst culture duration prior to transfer on live birth rate in FET cycles. In this retrospective observational study, we evaluated the influence of two distinct post-thaw blastocyst culture spans (2-4 h versus 20-22 h) on clinical pregnancy and live birth rate. A total of n = 1927 frozen-warmed cycles were included in the analysis. Among those, n = 885 warmed blastocysts were cultured for 2-4 h, and n = 1029 were kept in culture for 20-22 h prior to transfer; the remaining blastocysts did not survive the warming protocol. We observed no significant differences in live birth and clinical pregnancy rates between the two groups. The blastocyst morphological evaluation at transfer improved following the longer culture time. No differences between the two groups were found also for gestational and neonatal outcomes. This work shows that different post-thaw embryo culture timings do not negatively impact pregnancy outcomes. Overall, these results are important in the context of the embryological laboratory in order to better organize the workflow and avoid unnecessary timing-related workload.

The association between embryo storage time and treatment success in women undergoing freeze-all embryo transfer

OBJECTIVE

To investigate the relationship between the embryo frozen time and live birth rate (LBR) in women having a freeze-all cycle.

DESIGN

Retrospective cohort study.

SETTING

Academic hospital.

PATIENT(S)

Women who underwent their first vitrified-warmed cycles from January 2013 to December 2019.

INTERVENTION(S)

Embryo storage time.

MAIN OUTCOME MEASURE(S)

The primary outcome was the LBR.

RESULT(S)

A total of 14,928 women were eligible for the analysis. Women with the frozen time of transferred embryos for 2-5 months were associated with a higher LBR compared with other groups. The results were confirmed by an inverted U curve in the restricted cubic splines before as well as after adjustment for covariables, which suggested that an embryo storage time of 3-4 months was associated with the highest LBR. Subgroup analyses demonstrated that the inverted U curve relationship between embryo storage time and LBR was only observed in women with the high response. Sensitivity analyses in women with at least one good-quality embryo for transfer, in women aged <36 years at embryo transfer, or in women with double cleavage embryo transfer showed that the association remained valid. The association was weakened in women with single blastocyst transfer probably because of the small sample size in these women.

CONCLUSION(S)

An inverted U-shaped relationship was found between embryo storage time and treatment success in women with high ovarian response in freeze-all embryo transfer cycles. Prolonged storage time of >6 months was associated with reduced pregnancy rates.

Standardization of Post-Vitrification Human Blastocyst Expansion as a Tool for Implantation Prediction

The increased use of vitrified blastocysts has encouraged the development of various criteria for selecting the embryo most likely to implant. Post-thaw assessment methods and timetables vary among investigators. We investigated the predictive value of well-defined measurements of human blastocyst re-expansion, following a fixed incubation period. Post-thaw measurements were taken exactly at 0 and 120 ± 15 min. Minimum and maximum cross-sectional axes were measured. Three groups were defined: Group 1: embryos that continued to shrink by 10 µm or more; group 2: embryos that ranged from −9 to +9 µm; and group 3: re-expansion of 10 µm or more. Patient and morphokinetic data were collected and integrated into the analysis. A total of 115 cases were included. The clinical pregnancy rate for group 1 was 18.9%; group 2, 27%; and group 3, 51.2% (p = 0.007). Pre-thaw morphologic grading and morphokinetic scores of the study groups did not reveal differences. p-values were 0.17 for the pre-thaw morphologic score, 0.54 for KID3, and 0.37 for KID5. The patients’ demographic and clinical data were similar. The clinical pregnancy rate correlated with the degree of thawed blastocyst re-expansion measured 2 h after incubation. This standardized measure is suggested as a tool to predict the potential of treatment success before embryo transfer.

The Effect of Freezing Twice during Assisted Reproductive Technology on Perinatal and Neonatal Outcomes

Objective

The aim of this paper was to investigate whether two freeze-thaw cycles before embryo transfer may affect perinatal and neonatal outcomes.

Materials and Methods

A total of 8,028 frozen-thawed embryo transfer patients who became pregnant between March 2013 and September 2019 were included. The patients were divided into two groups: the oocyte cryopreservation (OC) group (N = 96) and the control group (N = 7932). Propensity score matching (PSM) was used to adjust the baseline characteristics of the two groups at a proportion of 1 : 4. There were 96 patients in the OC group and 369 patients in the control group after PSM. The pregnancy-related complications and neonatal conditions after delivery of the two groups were compared.

Results

The OC group had a higher stillbirth rate (3.1% vs. 0.3%, P = 0.029) than the control group after PSM. Moreover, a slightly higher pregnancy defect rate was found in the OC group. There was no significant difference in the rates of diabetes mellitus, hypertension during pregnancy, cesarean section, multiple births, low birth weight (LBW), or premature birth defects between the two groups.

Conclusions

Our findings demonstrate that performing frozen-thawed embryo transfer (FET) with cryopreserved oocytes was associated with a higher rate of stillbirth than FET with fresh oocytes. The incidences of diabetes, gestational hypertension, cesarean section, multiple births, LBW, premature birth, and birth defects of the two groups were not significantly different.

Optimizing embryological aspects of oocyte retrieval, oocyte denudation, and embryo loading for transfer: a state of the art review

Oocyte retrieval, oocyte denudation, and embryo transfer are crucial processes during assisted reproduction (ART). Air quality in the ART laboratory, temperature, pH of the media used and the time interval between oocyte retrieval and insemination are all critical factors. Anesthesia is required for oocyte retrieval, however evidence regarding the potential impact of different methods (general anesthesia, conscious sedation, and local anesthesia) on the clinical outcomes is unclear. The optimal timing of oocyte denudation following retrieval has not been established. Regarding the mechanical denudation process, there is a lack of evidence to demonstrate the safest minimum inner diameter of denuding pipettes used to complete the removal of granulosa cells surrounding the oocytes. During embryo transfer, many clinics worldwide flush the catheter before embryo loading, in an attempt to potentially rinse off any toxic agents; however, there is insufficient evidence to show that flushing the embryo transfer catheter before loading increases the success of ART outcome. Considering the serious gaps in knowledge in ART practice, the aim of this review is to provide an updated overview of the current knowledge regarding the various steps and techniques involved in oocyte retrieval, oocyte denudation, and embryo loading for transfer.

Glucocorticoid therapy in assisted reproduction

As glucocorticoids are well-known as important regulators of stress and the immune system, their function and clinical use have elicited substantial interest in the field of reproduction. In particular, the effect of glucocorticoid therapy on endometrial receptivity during assisted reproduction, including in vitro fertilization (IVF) cycles, has led to a great deal of interest and controversy. However, previous studies have not been able to provide consistent and reliable evidence due to their small, non-controlled designs and use of different criteria. Considering the potential risk of exposure to glucocorticoids for mothers and fetuses in early pregnancy, the use of glucocorticoids in IVF cycles should be carefully evaluated, including the balance between risk and benefit. To date, there is no conclusive evidence that the use of glucocorticoids improves the pregnancy rate in IVF cycles with unselected subjects, and a further investigation should be considered with a proper study design.

Ethical considerations of preconception and prenatal gene modification in the embryo and fetus

The National Academies of Sciences and Medicine 2020 consensus statement advocates the reinstatement of research in preconception heritable human genome editing (HHGE), despite the ethical concerns that have been voiced about interventions in the germline, and outlines criteria for its eventual clinical application to address monogenic disorders. However, the statement does not give adequate consideration to alternative technologies. Importantly, it omits comparison to fetal gene therapy (FGT), which involves gene modification applied prenatally to the developing fetus and which is better researched and less ethically contentious. While both technologies are applicable to the same monogenic diseases causing significant prenatal or early childhood morbidity, the benefits and risks of HHGE are distinct from FGT though there are important overlaps. FGT has the current advantage of a wealth of robust preclinical data, while HHGE is nascent technology and its feasibility for specific diseases still requires scientific proof. The ethical concerns surrounding each are unique and deserving of further discussion, as there are compelling arguments supporting research and eventual clinical translation of both technologies. In this Opinion, we consider HHGE and FGT through technical and ethical lenses, applying common ethical principles to provide a sense of their feasibility and acceptability. Currently, FGT is in a more advanced position for clinical translation and may be less ethically contentious than HHGE, so it deserves to be considered as an alternative therapy in further discussions on HHGE implementation.

The Effects of Different Post-thawed Culture Periods on Clinical Outcomes in Frozen Embryo Transfer Cycle

The purpose of this study is to evaluate the effects of different post-thawed culture periods on the clinical outcomes. 9381 frozen embryo transfer (FET) cycles were divided into three groups according to female age: < 35, 35-39, and > 39 years, and two groups depending on post-thawed culture period before transfer: short culture (2-3 h) group (S) and long culture (18-20 h) group (L). According to the increment number of post-thawed embryos, the L group divided into three groups: ≤ 2, one ≤ 2 and the other > 2, and > 2 groups. Pregnancy outcomes included the implantation rate (IR), clinical pregnancy rate (CPR), multiple pregnancy rate (MPR), live birth rate (LBR), and neonatal characteristics. Long post-thawed culture caused a significant increase in the IR, CPR, MPR, and LBR (p = 0.000, 0.004, 0.037, and 0.001; CI = 1.06-1.194, 1.042-1.237, 1.008-1.254, and 1.054-1.245, respectively), and blastomere increment number also had a significant effect on IR, CPR, MPR, and LBR (p = 0.000, 0.000, 0.000, and 0.000, respectively). No significant differences were present in neonatal characteristics between the two post-thawed culture groups. Singleton group had a higher average gestational age and birthweight as well as a lower cesarean section rate, preterm labor rate, and low birthweight rate than twins group. Long post-thawed culture was associated with higher IR, CPR, MPR, and LBR, and transferring a well-developed embryo after long post-thawed culture might be a viable embryo transfer strategy to decrease MPR while maintaining CPR and LBR.

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

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.

Prolonged Cryopreservation Negatively Affects Embryo Transfer Outcomes Following the Elective Freeze-All Strategy: A Multicenter Retrospective Study

BACKGROUND

With the development of embryo freezing and warming technology, frozen-thawed embryo transfer (FET) has been widely utilized. However, studies investigating the association between cryopreservation duration and FET outcomes are limited and controversial, and previous studies did not conduct stratification analyses based on demographic or clinical characteristics.

METHODS

This multicenter retrospective study included 17,826 women who underwent their first FET following the freeze-all strategy during the period from January 2014 to December 2018. Duration of cryopreservation was categorized into five groups: 3-8 weeks, 8-12 weeks, 12-26 weeks, 26-52 weeks, and >52 weeks. Modified Poisson regression and multivariate logistic regression were used to assess the association between cryostorage time of vitrified embryos and transfer outcomes. Moreover, further stratification analyses were performed according to variables with p <0.05 in multivariate models.

RESULTS

In this large multicenter study, we observed that storage duration was inversely associated with the possibility of pregnancy and live birth (p <0.001), but not with the risk of ectopic pregnancy and miscarriage. Stratification analyses based on maternal age, the number of oocytes retrieved, and condition of embryo transferred indicated that the inverse correlation was significant in the subpopulation with characteristics: (1) less than 40 years old, (2) more than 3 oocytes retrieved, and (3) only high-quality blastocysts transferred.

CONCLUSION

The results of this large, multicenter, retrospective study suggested that prolonged cryopreservation was inversely associated with the probability of pregnancy and live birth. Therefore, for patients who adopt a freeze-all strategy, early FET might achieve a better outcome.