Increasing levels of estradiol are deleterious to embryonic implantation because they directly affect the embryo

The molecular mechanism of naringin improving endometrial receptivity of OHSS rats

Controlling ovarian hyperstimulation syndrome (OHSS) in the controlled ovarian hyperstimulation treatment is necessary to increase the implantation success rate. This study aimed to explore the effect of naringin on the endometrial receptivity of OHSS rats. Female rats were randomly assigned to six groups: Blank, model, low-dose naringin (100 mg/kg/day), medium-dose naringin (200 mg/kg/day), high-dose naringin (400 mg/kg/day), and positive (0.18 mg/kg/day estradiol valerate) groups. Except for the blank group, rats established the OHSS model on Day 7, and their treatments were from Day 0 to 14, separately. Hematoxylin and eosin, immunohistochemical, and scanning electron microscopy were performed to detect the naringin effects on the endometrial receptivity of the OHSS model. Next, circRNAs transcriptome analysis was performed to screen circRNAs. Western blot analysis and real-time quantitative PCR were used to verify it. Our study showed that naringin treatments increased embryo number, endometrial thickness, pinopodes number, and Ki67 expression in the OHSS rats. Moreover, the result of circRNAs transcriptome sequencing showed that naringin significantly inhibited the rnocirc_008140 expression in the OHSS rats and significantly inhibited the changes of 28 gene ontology terms and three Kyoto Encyclopedia of Genes and Genomes pathways which were induced by OHSS. Abcc4 and Rps6ka5 genes were the enriched genes of those pathways. Finally, 24 miRNA target genes of rnocirc_008140 were predicted. Our study showed that naringin significantly improved the endometrial receptivity of OHSS rats to increase the embryo implantation success by reducing rnocirc_008140-adsorbed miRNAs to regulate Abcc4 and Rps6ka5 expression.

The construction of machine learning-based predictive models for high-quality embryo formation in poor ovarian response patients with progestin-primed ovarian stimulation

OBJECTIVE

To explore the optimal models for predicting the formation of high-quality embryos in Poor Ovarian Response (POR) Patients with Progestin-Primed Ovarian Stimulation (PPOS) using machine learning algorithms.

METHODS

A retrospective analysis was conducted on the clinical data of 4,216 POR cycles who underwent in vitro fertilization (IVF) / intracytoplasmic sperm injection (ICSI) at Sichuan Jinxin Xinan Women and Children's Hospital from January 2015 to December 2021. Based on the presence of high-quality cleavage embryos 72 h post-fertilization, the samples were divided into the high-quality cleavage embryo group (N = 1950) and the non-high-quality cleavage embryo group (N = 2266). Additionally, based on whether high-quality blastocysts were observed following full blastocyst culture, the samples were categorized into the high-quality blastocyst group (N = 124) and the non-high-quality blastocyst group (N = 1800). The factors influencing the formation of high-quality embryos were analyzed using logistic regression. The predictive models based on machine learning methods were constructed and evaluated accordingly.

RESULTS

Differential analysis revealed that there are statistically significant differences in 14 factors between high-quality and non-high-quality cleavage embryos. Logistic regression analysis identified 14 factors as influential in forming high-quality cleavage embryos. In models excluding three variables (retrieved oocytes, MII oocytes, and 2PN fertilized oocytes), the XGBoost model performed slightly better (AUC = 0.672, 95% CI = 0.636-0.708). Conversely, in models including these three variables, the Random Forest model exhibited the best performance (AUC = 0.788, 95% CI = 0.759-0.818). In the analysis of high-quality blastocysts, significant differences were found in 17 factors. Logistic regression analysis indicated that 13 factors influence the formation of high-quality blastocysts. Including these variables in the predictive model, the XGBoost model showed the highest performance (AUC = 0.813, 95% CI = 0.741-0.884).

CONCLUSION

We developed a predictive model for the formation of high-quality embryos using machine learning methods for patients with POR undergoing treatment with the PPOS protocol. This model can help infertility patients better understand the likelihood of forming high-quality embryos following treatment and help clinicians better understand and predict treatment outcomes, thus facilitating more targeted and effective interventions.

High estradiol levels in fresh embryo transfer cycles are not associated with detrimental impact on birth outcomes

PURPOSE

There is an unclear relationship between estradiol levels and fresh embryo transfer (ET) outcomes. We determined the relationship between estradiol on the day of trigger, in fresh ET cycles without premature progesterone elevation, and good birth outcomes (GBO).

METHODS

We identified autologous fresh ET cycles from 2015 to 2021 at multiple clinics in the USA. Patients with recurrent pregnancy loss, uterine factor, and elevated progesterone on the day of trigger (progesterone > 2 ng/mL or 3-day area under the curve > 4.5 ng/mL) were excluded. The primary outcome was GBO (singleton, term, live birth with appropriate weight). Log-binomial generalized estimating equations determined the likelihood of outcomes.

RESULTS

Of 17,608 fresh ET cycles, 5025 (29%) yielded GBO. Cycles with estradiol ≥ 4000 pg/mL had a greater likelihood of GBO compared to cycles < 1000 pg/mL (aRR = 1.32, 95% CI 1.13-1.54). Pairwise comparisons of estradiol between < 1000 pg/mL versus 1000-1999 pg/mL and 1000-1999 pg/mL versus 2000-2999 pg/mL revealed a higher likelihood of GBO with higher estradiol (aRR 0.83, 95% CI 0.73-0.95; aRR 0.91, 95% CI 0.85-0.97, respectively). Comparisons amongst more elevated estradiol levels revealed that the likelihood of GBO remained similar between groups (2000-2999 pg/mL versus 3000-3999 pg/mL, aRR 1.04, 95% CI 0.97-1.11; 3000-3999 pg/mL versus ≥ 4000 pg/mL, aRR 0.96, 95% CI 0.9-1.04).

CONCLUSION

In fresh ET cycles, higher estradiol levels were associated with an increased prevalence of GBO until estradiol 2000-2999 pg/mL, thereafter plateauing. In fresh ET candidates, elevated estradiol levels should not preclude eligibility though premature progesterone rise, and risk of ovarian hyperstimulation syndrome must still be considered.

Cut-off point of mature oocyte for routine clinical application of rescue IVM: a retrospective cohort study

BACKGROUND

The rescue in vitro mature(Rescue IVM) technique allows the use of immature oocytes collected in conventional COH to obtain more mature oocytes for fertilization through in vitro maturation. Some studies have shown that Rescue IVM could improve clinical outcomes in patients undergoing IVF/ICSI, but the effectiveness and the indications for the clinical application of this technique remain controversial. It remains to be studied whether Rescue IVM should be universally applied in all conventional IVF/ICSI cycles.

METHOD

This is a large retrospective cohort study that included a total of 22,135 female patients undergoing their first IVF treatment cycles. The effect of the number of mature oocytes(metaphaseII[MII]) on the cumulative live birth rate was investigated in a population with routine IVF/ICSI first. The receiver operating characteristic curve(ROC) analysis was used to explore the cut-off point of the number of MII affecting CLBR. Secondly, Patients undergoing ICSI with Rescue IVM were included in the analysis with those who underwent ICSI only during the same period, grouped according to the MII cut-off values. Multi-factor binary logistic regression and inverse probability weighting (IPW) were used to investigate whether Rescue IVM influenced the final cumulative live birth rate(CLBR).

RESULTS

The CLBR increased with the number of MIIoocytes (P < 0.001). The ROC analysis showed the cut-off point for the number of MIIoocytes to have a significant effect on CLBR was 9 (sensitivity 0.715, specificity 0.656). Furthermore, 912 patients who underwent ICSI with Rescue IVM were included and compared to those who underwent ICSI only during the same period, and found Rescue IVM significantly increased the number of available MIIoocytes. For patients with MII numbers < 9, Rescue IVM significantly improves their clinical pregnancy rate(55.6% vs. 46.7%, P = 0.001) and CLBR(65.4% vs. 48.1%, P < 0.001), but not for those patients with MII numbers ≥ 9.

CONCLUSION

This study further clarifies the candidates for the application of Rescue IVM technique: patients with an MII oocytes < 9 in a conventional IVF/ICSI cycle. In contrast, it is not necessary for patients who already have sufficient mature oocytes(≥ 9), to avoid over-medication.

Elevated estradiol levels on hCG trigger day adversely effects on the clinical pregnancy rates of blastocyst embryo transfer but not cleavage-stage embryo transfer in fresh cycles: a retrospective cohort study

Background

Elevated estradiol (E₂) levels are an inevitable outcome of the controlled ovulation hyperstimulation. However, the effect of this change on pregnancy is still uncertain. Our study aimed to analyze the impact of increased serum E₂ at the day of human chorionic gonadotropin (hCG) administration on the clinical outcomes of women with fresh embryo transfer (ET) cycles.

Methods

This study included 3,009 fresh ET cycles from October 2015 to September 2021. Based on the stage of embryos transferred, these cycles were categorized into the cleavage group and blastocyst group. Both groups were then divided into four sets according to E₂ levels when hCG was administered: set 1 (E₂ ≤ 2,000 pg/ml), set 2 (E₂ = 2,001-3,000 pg/ml), set 3 (E₂ = 3,001-4,000 pg/ml), and set 4 (E₂ > 4,000 pg/ml). The primary outcome was the clinical pregnancy rate (CPR). Binary logistics regression analysis was established to explore the association between CPR and E2 levels. Specifically, the threshold effect of serum E2 on CPR was revealed using the two-piecewise linear regression analyses.

Results

The multivariate regression model in the cleavage group showed that patients' CPR in set 4 was 1.59 times higher than those in reference set 1, but the statistical difference was insignificant (P = 0.294). As for the blastocyst group, patients in set 4 had a lower CPR with adjusted ORs of 0.43 (P = 0.039) compared to patients in set 1. The inflection point for the blastocyst group was 39.7 pg/dl according to the results of the two-piecewise linear regression model. When E₂ levels were over the point, the CPR decreased by 17% with every 1 pg/dl increases in serum E₂ (adjusted OR = 0.83, 95% CI [0.72-0.96], P = 0.012).

Conclusions

Elevated E₂ levels (>39.7 pg/dl) on hCG trigger day were associated with decreased CPR in patients with fresh blastocyst ET. However, it had no similar effect on the CPR of patients with fresh cleavage-stage ET.

The effect of peak serum estradiol level during ovarian stimulation on cumulative live birth and obstetric outcomes in freeze-all cycles

Objective

To determine whether the peak serum estradiol (E2) level during ovarian stimulation affects the cumulative live birth rate (CLBR) and obstetric outcomes in freeze-all cycles.

Methods

This retrospective cohort study involved patients who underwent their first cycle of in vitro fertilization followed by a freeze-all strategy and frozen embryo transfer cycles between January 2014 and June 2019 at a tertiary care center. Patients were categorized into four groups according to quartiles of peak serum E2 levels during ovarian stimulation (Q1-Q4). The primary outcome was CLBR. Secondary outcomes included obstetric and neonatal outcomes of singleton and twin pregnancies. Poisson or logistic regression was applied to control for potential confounders for outcome measures, as appropriate. Generalized estimating equations were used to account for multiple cycles from the same patient for the outcome of CLBR.

Results

A total of 11237 patients were included in the analysis. Cumulatively, live births occurred in 8410 women (74.8%). The live birth rate (LBR) and CLBR improved as quartiles of peak E2 levels increased (49.7%, 52.1%, 54.9%, and 56.4% for LBR; 65.1%, 74.3%, 78.4%, and 81.6% for CLBR, from the lowest to the highest quartile of estradiol levels, respectively, P<0.001). Such association remained significant for CLBR after accounting for potential confounders in multivariable regression models, whereas the relationship between LBR and peak E2 levels did not reach statistical significance. In addition, no significant differences were noticed in adverse obstetric and neonatal outcomes (gestational diabetes mellitus, pregnancy-induced hypertension, preeclampsia, placental disorders, preterm birth, low birthweight, and small for gestational age) amongst E2 quartiles for either singleton or twin live births, both before and after adjustment.

Conclusion

In freeze-all cycles, higher peak serum E2 levels during ovarian stimulation were associated with increased CLBR, without increasing the risks of adverse obstetric and neonatal outcomes.

Reconsidering "low-dose"-Impacts of oral estrogen exposure during preimplantation embryo development

Perturbations of estrogen signaling during developmental stages of high plasticity may lead to adverse effects later in life. Endocrine-disrupting chemicals (EDC) are compounds that interfere with the endocrine system by particularly mimicking the action of endogenous estrogens as functional agonists or antagonists. EDCs compose synthetic and naturally occurring compounds discharged into the environment, which may be taken up via skin contact, inhalation, orally due to contaminated food or water, or via the placenta during in utero development. Although estrogens are efficiently metabolized by the liver, the role of circulating glucuro- and/or sulpho-conjugated estrogen metabolites in the body has not been fully addressed to date. Particularly, the role of intracellular cleavage to free functional estrogens could explain the hitherto unknown mode of action of adverse effects of EDC at very low concentrations currently considered safe. We summarize and discuss findings on estrogenic EDC with a focus on early embryonic development to highlight the need for reconsidering low dose effects of EDC.

Estrogen signaling encourages blastocyst development and implantation potential

PURPOSE

Estrogen is well-known for preparing uterine receptivity. However, its roles in regulating embryo development and implantation are unclear. Our objective was to characterize estrogen receptor 1 (ESR1) in human and mouse embryos and determine the effect of estradiol (E2) supplementation on pre- and peri-implantation blastocyst development.

METHODS

Mouse embryos, 8-cell through hatched blastocyst stages, and human embryonic days 5-7 blastocysts were stained for ESR1 and imaged using confocal microscopy. We then treated 8-cell mouse embryos with 8 nM E2 during in vitro culture (IVC) and examined embryo morphokinetics, blastocyst development, and cell allocation into the inner cell mass (ICM) and trophectoderm (TE). Finally, we disrupted ESR1, using ICI 182,780, and evaluated peri-implantation development.

RESULTS

ESR1 exhibits nuclear localization in early blastocysts followed by aggregation, predominantly in the TE of hatching and hatched blastocysts, in human and mouse embryos. During IVC, most E2 was absorbed by the mineral oil, and no effect on embryo development was found. When IVC was performed without an oil overlay, embryos treated with E2 exhibited increased blastocyst development and ICM:TE ratio. Additionally, embryos treated with ICI 182,780 had significantly decreased trophoblast outgrowth during extended embryo culture.

CONCLUSION

Similar ESR1 localization in mouse and human blastocysts suggests a conserved role in blastocyst development. These mechanisms may be underappreciated due to the use of mineral oil during conventional IVC. This work provides important context for how estrogenic toxicants may impact reproductive health and offers an avenue to further optimize human-assisted reproductive technology (ART) to treat infertility.

Brief and long co-incubation of sperm and oocytes for in vitro fertilization: a meta-analysis of randomized controlled trials

Background

There is still no consensus on the optimal time of oocyte–sperm co-incubation during in vitro fertilization and embryo transfer (IVF-ET). The aim of this meta-analysis was to compare the effects of brief (1-6 h) and long (16-24 h) gametes co-incubation time on IVF outcomes.

Methods

The study protocol was registered online through PROSPERO (CRD42022337503) and PRISMA guidelines were followed in the present study. The following databases were searched from inception to May 2022 for randomized controlled trials (RCTs): PubMed, Embase, Cochrane library, Web of Science, using search terms related to IVF, gametes, time of co-incubation and reproductive outcome measure. Studies comparing outcomes of brief co-incubation to that of long co-incubation during IVF, and reporting primary outcome (live birth rate), secondary outcomes (clinical pregnancy rate; ongoing pregnancy rate; miscarriage rate; normal fertilization rate; polyspermy rate; top-quality embryo rate; implantation rate) were searched. A total of 11 studies were included in the meta-analysis. Combined odds ratio (OR) and 95% confidence interval (CI) were calculated for the data. Statistical heterogeneity analysis between studies was assessed by Cochran Q and I² statistic with a significant threshold of P < 0.05. Methodologic quality assessment of RCTs was made for potential risk of bias with Cochrane Risk of Bias Tool.

Results

Compared to long-term co-incubation, brief co-incubation had an advantage in increasing implantation rate (OR: 1.97, 95% CI: 1.52–2.57), ongoing pregnancy rate (OR: 2.18, 95% CI: 1.44–3.29) and top-quality embryo rate (OR: 1.17, 95% CI: 1.02–1.35). However, brief co-incubation of gametes had no advantages in the live-birth rate (OR: 1.09, 95% CI: 0.72–1.65), miscarriage rate (OR: 1.32, 95% CI: 0.55–3.18), clinical pregnancy rate (OR: 1.36, 95% CI: 0.99–1.87) and polyspermy rate (OR: 0.80, 95% CI: 0.48–1.33) than long-term co-incubation. Additionally, the brief co-incubation was associated with lower normal fertilization rate (OR: 0.89, 95% CI: 0.80–0.99), compared with long co-incubation.

Conclusions

Brief co-incubation of gametes had the advantages in increasing implantation rate, ongoing pregnancy rate and top-quality embryo rate than long-term co-incubation. However, the live-birth rate displayed no difference between the two in vitro fertilization methods. Gametes co-incubation time should be individualized according to each patient’s IVF history, infertility causes and the semen parameters.

Effects of trigger-day progesterone in the preimplantation genetic testing cycle on the embryo quality and pregnancy outcomes of the subsequent first frozen-thawed blastocyst transfer

Objective

To assess whether progesterone (P) levels on the trigger day during preimplantation genetic testing (PGT) cycles are associated with embryo quality and pregnancy outcomes in the subsequent first frozen-thawed blastocyst transfer (FET) cycle.

Methods

In this retrospective analysis, 504 eligible patients who underwent ICSI followed by frozen-thawed embryo transfer (FET) with preimplantation genetic test (PGT) between December 2014 and December 2019 were recruited. All patients adopted the same protocol, namely, the midluteal, short-acting, gonadotropin-releasing hormone agonist long protocol. The cutoff P values were 0.5 and 1.5 ng/ml when serum P was measured on the day of human chorionic gonadotropin (HCG) administration, and cycles were grouped according to P level on the day of HCG administration. Furthermore, the effect of trigger-day progesterone on embryo quality and the subsequent clinical outcome of FET in this PGT population was evaluated.

Results

In total, 504 PGT cycles were analyzed. There was no significant difference in the number of euploid blastocysts, top-quality blastocysts, euploidy rate, or miscarriage rate among the three groups (P>0.05). The 2PN fertilization rate (80.32% vs. 80.17% vs. 79.07%) and the top-quality blastocyst rate (8.71% vs. 8.24% vs. 7.94%) showed a downward trend with increasing P, and the between-group comparisons showed no significant differences (P>0.05). The clinical pregnancy rate (41.25% vs. 64.79%; P<0.05) and live birth rate (35.00% vs. 54.93%; P<0.05) in subsequent FET cycles were substantially lower in the high-P group than in the P ≤ 0.5 ng/ml group. After adjustments were made for confounding variables, multivariate logistic regression analysis revealed that the high-P group had a lower clinical pregnancy rate (adjusted OR, 0.317; 95% CI, 0.145-0.692; P=0.004) and live birth rate (adjusted OR, 0.352; 95% CI, 0.160-0.773; P=0.009) than the low-P group in subsequent FET cycles, and the differences were significant.

Conclusions

This study demonstrates that in the PGT population, elevated P on the trigger day may diminish the top-quality blastocyst rate (although there is no difference in the euploidy rate). Trigger-day P is an important factor influencing clinical outcomes in subsequent FET cycles.

Effect of the ratios of estradiol increase on the outcome of in vitro fertilization-embryo transfer with antagonist regimens: a single center retrospective cohort study

BACKGROUND

The outcome of in vitro fertilization-embryo transfer (IVF) is often determined according to follicle and estradiol levels following gonadotropin stimulation. In previous studies, although most of them analyzed the estrogen level from ovaries or the average estrogen level of a single follicle, there was no study on the ratio of estrogen increase, which was also correlated with pregnancy outcomes in the clinic. This study aimed to make timely adjustments to follow-up medication to improve clinical outcomes based on the potential value of estradiol growth rate.

METHODS

We comprehensively analyzed estrogen growth during the entire ovarian stimulation period. Serum estradiol levels were measured on the day of gonadotropin treatment (Gn1), five days later (Gn5), eight days later (Gn8), and on the trigger day (HCG). This ratio was used to determine the increase in estradiol levels. According to the ratio of estradiol increase, the patients were divided into four groups: A1 (Gn5/Gn1 ≤ 6.44), A2 (6.44 < Gn5/Gn1 ≤ 10.62), A3 (10.62 < Gn5/Gn1 ≤ 21.33), and A4 (Gn5/Gn1 > 21.33); B1 (Gn8/Gn5 ≤ 2.39), B2 (2.39 < Gn8/Gn5 ≤ 3.03), B3 (3.03 < Gn8/Gn5 ≤ 3.84), and B4 (Gn8/Gn5 > 3.84). We analyzed and compared the relationship between data in each group and pregnancy outcomes.

RESULTS

In the statistical analysis, the estradiol levels of Gn5 (P = 0.029, P = 0.042), Gn8 (P < 0.001, P = 0.001), and HCG (P < 0.001, P = 0.002), as well as Gn5/Gn1 (P = 0.004, P = 0.006), Gn8/Gn5 (P = 0.001, P = 0.002), and HCG/Gn1 (P < 0.001, P < 0.001) both had clinical guiding significance, and lower one significantly reduced the pregnancy rate. The outcomes were positively linked to groups A (P = 0.036, P = 0.043) and B (P = 0.014, P = 0.013), respectively. The logistical regression analysis revealed that group A1 (OR = 0.376 [0.182-0.779]; P = 0.008*, OR = 0.401 [0.188-0.857]; P = 0.018*) and B1 (OR = 0.363 [0.179-0.735]; P = 0.005*, OR = 0.389 [0.187-0.808]; P = 0.011*) had opposite influence on outcomes.

CONCLUSION

Maintaining a serum estradiol increase ratio of at least 6.44 on Gn5/Gn1 and 2.39 on Gn8/Gn5 may result in a higher pregnancy rate, especially in young people.

Developmental potential of different embryos on day 3: a retrospective study

To investigate how different quality of day 3 (D3) embryos affect blastocyst formation and clinical outcomes. This retrospective study analysed 699 patients undergoing assisted reproductive technology (ART) between January 2017 and February 2021. A total of 2517 D3 embryos were transferred to blastocyst medium for extended culture. D3 embryos were divided into five groups. Grade A, 6-10 cells, symmetrical blastomeres and <20% fragmentation; grade B, 6-10 cells, uneven blastomeres and ≥20% fragmentation; grade C, >10 cells, symmetrical blastomeres and <20% fragmentation; grade D, >10 cells, uneven blastomeres and ≥20% fragmentation; grade E, <6 cells. Status of day 5 (D5) and day 6 (D6) blastocysts and the clinical outcomes (blastocyst transfer) of each D3 embryo were recorded. The grade C group showed a higher D5 blastocyst formation rate and a high-quality blastocyst rate than other groups (p<.05). However, the clinical pregnancy rates in the grade A group were higher than other groups (p<.05). Embryos with low speed of development (grade E group) showed considerable clinical outcomes that were still worth investigating. D3 embryos with less fragmentation and ≥6 symmetrical blastomeres revealed a higher developmental potential, while embryos with 6-10 blastomeres showed the ideal clinical outcomes.Impact StatementWhat is already known on this subject? Accurate embryo evaluation can effectively reflect the developmental potential of different embryos. The number of blastomeres, proportion of fragmentation, and blastomere symmetry are three important and popular morphologic parameters used for evaluating day 3 (D3) embryos. However, in existing reports, combining these three parameters for embryo evaluation often results in different results. This is because different researchers have chosen different criteria for these three parameters.What do the results of this study add? In this retrospective study, we summarised the medical records of our reproductive centre in the past three years, redefined the evaluation method of the D3 embryos, and analysed the corresponding developmental potential and clinical outcomes. We conclude that although the embryonic development potential of grade C embryos (>10 cells, symmetrical blastomeres and/or <20% fragmentation) is relatively good, the results of grade A embryos (6-10 cells, symmetrical blastomeres and/or <20% fragmentation) are better in terms of clinical outcomes.What are the implications of these findings for clinical practice and/or further research? We believe this is meaningful for embryologists to choose embryos for transfer and predict the clinical outcome of IVF cycles.

Clinical Outcome of Day-3 Cleavage Slow-Growing Embryos at Different Cleavage Rates after Overnight Culture: A Cohort Retrospective Study

INTRODUCTION

We explored the association between clinical outcomes and the cleavage rate of day-3 cleavage slow-growing embryos after overnight culture.

METHODS

The data collected from 303 frozen embryo transfer (FET) cycles with 606 4-cell or 5-cell embryos cultured overnight (18-22 h) after thawing were analyzed. Based on the growth rate after the overnight culture, the embryos were divided into three groups: no embryo reaching eight cells (Group I), either one of the two embryos reaching eight cells (Group II), and both two embryos reaching eight cells or more (Group III). A statistical analysis of the different clinical outcomes from the three groups was performed.

RESULTS

Biochemical pregnancy rate (OR 3.22; p = 0.001), implantation rate (OR 2.44; p = 0.002), clinical pregnancy rate (OR 3.04; p = 0.001), ongoing pregnancy rate (OR 3.14; p = 0.001), and live birth rate (OR 2.78; p = 0.004) were significantly higher in Group III as compared to Group I. Group II had a significantly higher biochemical pregnancy rate (OR 2.02; p = 0.013) and implantation rate (OR 1.77; p = 0.019) than Group I.

CONCLUSIONS

The capability of day-3 cleavage slow-growing embryos to reach eight cells, especially that of two embryos reaching eight cells by overnight culture, appear to result in a better pregnancy outcome.

Association between serum estradiol level on day of progesterone start and outcomes from frozen blastocyst transfer cycles utilizing oral estradiol

PURPOSE

Supraphysiologic serum estradiol levels may negatively impact the likelihood of conception and live birth following IVF. The purpose of this study is to determine if there is an association between serum estradiol level on the day of progesterone start and clinical outcomes following programmed frozen blastocyst transfer cycles utilizing oral estradiol.

METHODS

This is a retrospective cohort study at an academic fertility center analyzing 363 patients who underwent their first autologous single (SET) or double frozen embryo transfer (DET) utilizing oral estradiol and resulting in blastocyst transfer from June 1, 2012, to June 30, 2018. Main outcome measures included implantation, clinical pregnancy, live birth, and miscarriage rates. Cycles were stratified by quartile of serum estradiol on the day of progesterone start and separately analyzed for SET cycles only. Poisson and Log binomial regression were used to calculate relative risks (RR) with 95% confidence intervals (CI) for implantation, clinical pregnancy, live birth, and miscarriage with adjustments made for age and BMI.

RESULTS

Cycles with the highest quartile of estradiol (mean 528 pg/mL) were associated with lower risks of implantation (RR 0.66, CI 0.50-0.86), ongoing pregnancy (RR 0.66, CI 0.49-0.88), and live birth (RR 0.70, CI 0.52-0.94) compared with those with the lowest estradiol quartile (mean 212 pg/mL). Similar findings were seen for analyses limited to SETs. There was no significant difference in miscarriage rate or endometrial thickness between groups.

CONCLUSION

High levels of serum estradiol on the day of progesterone start may be detrimental to implantation, pregnancy, and live birth following frozen blastocyst transfer.

Cleavage-stage versus blastocyst-stage embryo transfer in assisted reproductive technology

BACKGROUND

Advances in embryo culture media have led to a shift in in vitro fertilisation (IVF) practice from cleavage-stage embryo transfer to blastocyst-stage embryo transfer. The rationale for blastocyst-stage transfer is to improve both uterine and embryonic synchronicity and enable self selection of viable embryos, thus resulting in better live birth rates.

OBJECTIVES

To determine whether blastocyst-stage (day 5 to 6) embryo transfer improves the live birth rate (LBR) per fresh transfer, and other associated outcomes, compared with cleavage-stage (day 2 to 3) embryo transfer.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, CENTRAL, MEDLINE, Embase, PsycINFO, and CINAHL, from inception to October 2021. We also searched registers of ongoing trials and the reference lists of studies retrieved.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) which compared the effectiveness of IVF with blastocyst-stage embryo transfer versus IVF with cleavage-stage embryo transfer.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Our primary outcomes were LBR per fresh transfer and cumulative clinical pregnancy rates (cCPR). Secondary outcomes were clinical pregnancy rate (CPR), multiple pregnancy, high-order multiple pregnancy, miscarriage (all following first embryo transfer), failure to transfer embryos, and whether supernumerary embryos were frozen for transfer at a later date (frozen-thawed embryo transfer). We assessed the overall quality of the evidence for the main comparisons using GRADE methods.

MAIN RESULTS

We included 32 RCTs (5821 couples or women). The live birth rate following fresh transfer was higher in the blastocyst-stage transfer group (odds ratio (OR) 1.27, 95% confidence interval (CI) 1.06 to 1.51; I² = 53%; 15 studies, 2219 women; low-quality evidence). This suggests that if 31% of women achieve live birth after fresh cleavage-stage transfer, between 32% and 41% would do so after fresh blastocyst-stage transfer. We are uncertain whether blastocyst-stage transfer improves the cCPR. A post hoc analysis showed that vitrification could increase the cCPR. This is an interesting finding that warrants further investigation when more studies using vitrification are published. The CPR was also higher in the blastocyst-stage transfer group, following fresh transfer (OR 1.25, 95% CI 1.12 to 1.39; I² = 51%; 32 studies, 5821 women; moderate-quality evidence). This suggests that if 39% of women achieve a clinical pregnancy after fresh cleavage-stage transfer, between 42% and 47% will probably do so after fresh blastocyst-stage transfer. We are uncertain whether blastocyst-stage transfer increases multiple pregnancy (OR 1.05, 95% CI 0.83 to 1.33; I² = 30%; 19 studies, 3019 women; low-quality evidence) or miscarriage rates (OR 1.12, 95% CI 0.90 to 1.38; I² = 24%; 22 studies, 4208 women; low-quality evidence). This suggests that if 9% of women have a multiple pregnancy after fresh cleavage-stage transfer, between 8% and 12% would do so after fresh blastocyst-stage transfer. However, a sensitivity analysis restricted only to studies with low or 'some concerns' for risk of bias, in the subgroup of equal number of embryos transferred, showed that blastocyst transfer probably increases the multiple pregnancy rate. Embryo freezing rates (when there are frozen supernumerary embryos for transfer at a later date) were lower in the blastocyst-stage transfer group (OR 0.48, 95% CI 0.40 to 0.57; I² = 84%; 14 studies, 2292 women; low-quality evidence). This suggests that if 60% of women have embryos frozen after cleavage-stage transfer, between 37% and 46% would do so after blastocyst-stage transfer. Failure to transfer any embryos was higher in the blastocyst transfer group (OR 2.50, 95% CI 1.76 to 3.55; I² = 36%; 17 studies, 2577 women; moderate-quality evidence). This suggests that if 1% of women have no embryos transferred in planned fresh cleavage-stage transfer, between 2% and 4% probably have no embryos transferred in planned fresh blastocyst-stage transfer. The evidence was of low quality for most outcomes. The main limitations were serious imprecision and serious risk of bias, associated with failure to describe acceptable methods of randomisation.

AUTHORS' CONCLUSIONS

There is low-quality evidence for live birth and moderate-quality evidence for clinical pregnancy that fresh blastocyst-stage transfer is associated with higher rates of both than fresh cleavage-stage transfer. We are uncertain whether blastocyst-stage transfer improves the cCPR derived from fresh and frozen-thawed cycles following a single oocyte retrieval. Although there is a benefit favouring blastocyst-stage transfer in fresh cycles, more evidence is needed to know whether the stage of transfer impacts on cumulative live birth and pregnancy rates. Future RCTs should report rates of live birth, cumulative live birth, and miscarriage. They should also evaluate women with a poor prognosis to enable those undergoing assisted reproductive technology (ART) and service providers to make well-informed decisions on the best treatment option available.

Association of embryo transfer type with infertility in endometriosis: a systematic review and meta-analysis

PURPOSE

The study aims to evaluate whether frozen embryo transfer can restore optimal receptivity leading to better assisted reproductive technology outcomes in women with endometriosis.

METHODS

This systematic review and meta-analysis, conducted from January 10, 2021 to July 1, 2021, searched the Cochrane Library, PubMed, Embase, Web of Science, OVID, and Clinicaltrials.gov databases from inception to January 10, 2021. The search strategy combined search terms as follows: ("endometriosis" OR "deep endometriosis" OR "endometrioma") AND ("frozen-thawed embryo transfer" OR "frozen embryo transfer" OR "freeze-all strategy") AND ("pregnancy outcome" OR "live birth rate" OR "clinical pregnancy rate" OR "miscarriage rate"). No publication time or language limits were set during the searches. In addition, references of the related articles were searched by hand. Patients were included if they had a history of endometriosis and had received fresh or frozen embryo transfer. Only the first transfer cycle was included. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to express outcomes, and data synthesis was conducted using RevMan, version 5.4 software.

RESULTS

A total of six studies with moderate methodologic quality were retrieved in the meta-analysis. The studies included 3010 women with endometriosis who wanted to conceive; 1777 (59.0%) had frozen embryo transfer, and 1233 (41.0%) had fresh embryo transfer. There was a significantly higher frequency of live births in the frozen embryo group than in the fresh embryo group (OR, 1.53; 95% CI, 1.13-2.08; P = .007). Despite a similar clinical pregnancy rate in the two groups (OR, 1.26; 95% CI, 0.95-1.69; P = .11), the difference in miscarriage rate was significant (OR, 0.70; 95% CI, 0.50-0.97; P = .03). Evidence quality was considered moderate.

CONCLUSION

Cryopreserved embryo transfer has resulted in preferable reproduction outcomes when compared with fresh embryo transfer in patients with endometriosis, but the evidence is not yet abundant. More strictly designed research is needed to evaluate whether frozen embryo transfer leads to better reproductive outcomes in women with endometriosis compared with those receiving fresh embryo transfer.

REGISTRATION NUMBER

PROSPERO CRD42021248313.

Cross-species meta-analysis of transcriptome changes during the morula-to-blastocyst transition: metabolic and physiological changes take center stage

The morula-to-blastocyst transition (MBT) culminates with formation of inner cell mass (ICM) and trophectoderm (TE) lineages. Recent studies identified signaling pathways driving lineage specification, but some features of these pathways display significant species divergence. To better understand evolutionary conservation of the MBT, we completed a meta-analysis of RNA sequencing data from five model species and ICMTE differences from four species. Although many genes change in expression during the MBT within any given species, the number of shared differentially expressed genes (DEGs) is comparatively small, and the number of shared ICMTE DEGs is even smaller. DEGs related to known lineage determining pathways (e.g., POU5F1) are seen, but the most prominent pathways and functions associated with shared DEGs or shared across individual species DEG lists impact basic physiological and metabolic activities, such as TCA cycle, unfolded protein response, oxidative phosphorylation, sirtuin signaling, mitotic roles of polo-like kinases, NRF2-mediated oxidative stress, estrogen receptor signaling, apoptosis, necrosis, lipid and fatty acid metabolism, cholesterol biosynthesis, endocytosis, AMPK signaling, homeostasis, transcription, and cell death. We also observed prominent differences in transcriptome regulation between ungulates and nonungulates, particularly for ICM- and TE-enhanced mRNAs. These results extend our understanding of shared mechanisms of the MBT and formation of the ICM and TE and should better inform the selection of model species for particular applications.

High ovarian response to ovarian stimulation: effect on morphokinetic milestones and cycle outcomes

PURPOSE

To assess the effect of high ovarian response on oocyte quality and ovarian stimulation cycle outcomes.

METHODS

A retrospective cohort study conducted at three IVF units. The high ovarian response (HOR) and polycystic ovary syndrome (PCOS) with HOR (PCOS HOR) groups included 151 and 13 women who underwent controlled ovarian stimulation (COS) resulting in more than 15 retrieved oocytes, for a total of 1863 and 116 cultured embryos, respectively. The normal ovarian response (NOR) group comprised 741 women with 6-15 retrieved oocytes, resulting in 4907 cultured embryos. Data collected included fresh cycle data and pregnancy rates, in addition to annotation of morphokinetic events from time of pronuclei fading to time of initiation of blastocyst formation of embryos cultured in a time lapse incubator, including occurrence of direct unequal cleavage at first cleavage (DUC-1) (less than 5 h from two to three blastomeres). Comparison was made between morphokinetic parameters between the 3 groups. Cycle outcomes were compared in the high vs. normal ovarian response groups.

RESULTS

Oocyte maturation rate was significantly lower in the HOR vs. NOR groups (56.5% vs. 90.0%, p < 0.001), while the fertilization rates were similar (60.2% vs. 58.1%, p = 0.397). The prevalence of DUC-1 embryos was higher in the PCOS HOR and the HOR groups as compared to the NOR group (22.7% vs. 16.2% and 12.0%, respectively, p < 0.001). After exclusion of DUC-1 embryos, remaining embryos from the NOR and HOR groups reached the morphokinetic milestones at similar rates, with comparable implantation and clinical pregnancy rates, while the PCOS HOR showed shorter time to 5 blastomeres compared to the NOR and HOR groups.

CONCLUSIONS

High ovarian response might be associated with decreased oocyte quality, manifested as a higher proportion of immature oocytes and higher rate of direct uneven cleavage embryos, while embryos exhibiting normal first cleavage have similar temporal milestones and implantation potential.

Is there still a role for a cleavage-stage embryo transfer?

Objective

To determine whether pregnancy outcomes are poor or futile when an intended day 5 transfer is converted to a cleavage-stage transfer because of poor embryo development or a lower number of embryos.

Design

Retrospective cohort study.

Setting

Academic medical center.

Patient(s)

Women with a limited number of embryos, defined as ≤6 two pronuclear embryos, after in vitro fertilization.

Intervention(s)

Patients who had a cleavage-stage transfer were age matched with patients who had a day 5 transfer.

Main Outcome Measure(s)

Live birth rate.

Result(s)

A total of 146 women were included in the study with 73 women in each group. Cleavage-stage transfer was associated with significantly lower implantation and clinical pregnancy rates compared with those of day 5 transfer. Although the live birth rate of the cleavage-stage transfer group was lower than that of the day 5 transfer group (25% vs. 40%, respectively), the cleavage-stage transfer still resulted in a live birth rate of 25%. A subanalysis comparing women who did and did not achieve live birth after cleavage-stage transfer demonstrated a live birth rate of 27% when at least one grade A embryo was transferred vs. 17% when a lesser quality embryo (grade B or C) was transferred.

Conclusion(s)

As expected, the live birth rate after cleavage-stage transfer was lower than that after day 5 transfer. However, the live birth rate of cleavage-stage transfer still fell into acceptable practice, >5%, for patients who were otherwise at very high risk of having no day 5 embryo transfer. Extended culture may not be necessary for all patients.

Evaluation of the relationship between serum estradiol levels on human chorionic gonadotropin administration day and intracytoplasmic sperm injection outcomes: A retrospective population-based study

Background

The correlation between high estradiol (E2) levels induced by controlled ovarian hyperstimulation (COH) and pregnancy is controversial.

Objective

To assess the effect of serum E2 levels on the day of human chorionic gonadotropin administration on the intracytoplasmic sperm injection (ICSI) outcome.

Materials and Methods

The current study included 551 participants who had undergone ICSI between May 2014 and May 2016. Based on E2 levels, the individuals aged < 37 yr (n = 502) and 37-42 yr (n = 49) were categorized into six and three groups, respectively. ICSI outcomes including the number of retrieved oocytes (NRO), number of embryos (NE), pregnancy rate, and abortion rate were analyzed in both groups.

Results

Among participants aged < 37 yr, the NRO and NE were 8.69 ± 3.82 and 5.24 ± 2.32, respectively and they had a significant correlation with the E2 level on human chorionic gonadotropin administration day (p < 0.001 for both). Among participants aged > 37 yr, NRO and NE were 5.18 ± 3.17 and 3.40 ± 2.23, respectively, and the NRO (p < 0.001), NE (p < 0.001), pregnancy rate (p < 0.001), abortion rate (p = 0.007), and the number of grade A and B embryos (p = 0.003) had a significant association with the E2 level.

Conclusion

COH is a costly procedure that may have negative effects on endometrial receptivity. Thus, in order to prevent these effects and also to reduce the costs of COH, we recommend gaining optimum number of oocytes rather than maximum number during the procedure.

The association between alcohol intake and fecundability during menstrual cycle phases

STUDY QUESTION

Is increased alcohol intake in different phases of the menstrual cycle associated with fecundability in women?

SUMMARY ANSWER

Heavy intake (>6 drinks/week) of alcoholic beverages in the luteal phase and ovulatory subphase was associated with reduced odds of conception; moderate intake (3-6 drinks/week) during the luteal phase was also associated with reduced fecundability.

WHAT IS KNOWN ALREADY

Despite strong indications for increased risk of infertility among drinking women with intention to conceive, inconsistencies in previous results point to possible residual confounding, and have not thoroughly investigated timing of drinking and other drinking patterns during the menstrual cycle.

STUDY DESIGN, SIZE, DURATION

Participants in The Mount Sinai Study of Women Office Workers (MSSWOW), a prospective cohort study of fertility, were recruited and followed between 1990 and 1994, and completed daily diaries reporting their alcohol intake (type and number of drinks) for a maximum of 19 months of follow-up (N = 413).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were between 19 and 41 years of age. After completion of baseline surveys, they were asked to record their alcoholic beverage intake as number of drinks of beer, wine, and liquor per day, in addition to other exposures such as caffeine and smoking. Furthermore, they submitted urine samples each month to assess pregnancy. Menstrual cycle phases were calculated using the Knaus-Ognio approach. Discrete survival analysis methods were employed to estimate the association between categories of alcohol intake in each phase of menstrual cycle and fecundability.

MAIN RESULTS AND THE ROLE OF CHANCE

In the luteal phase, both moderate drinking (3-6 drinks/week, Fecundability Odds Ratio (FOR)=0.56, CI: 0.31, 0.98) and heavy drinking (>6 drinks/week, FOR = 0.51, CI: 0.29, 0.89) were associated with a reduction in fecundability, compared to non-drinkers. For the follicular phase, heavy drinking in the ovulatory sub-phase (FOR = 0.39, CI: 0.19, 0.72) was similarly associated with reduced fecundability, compared to non-drinkers. For the pre-ovulatory sub-phase, heavy drinking (>6 drinks/week, FOR = 0.54, CI: 0.29, 0.97) was associated with reduction in fecundability, but this association was inconsistent when subjected to sensitivity tests. Each extra day of binge drinking was associated with 19% (FOR = 0.81, CI: 0.63, 0.98), and 41% (FOR = 0.59, CI: 0.33, 0.93) reduction in fecundability for the luteal phase and ovulatory sub-phase respectively, but no association was observed in the pre-ovulatory sub-phase. No meaningful differences in fecundability between beverages were observed in any menstrual phase.

LIMITATIONS, REASONS FOR CAUTION

Patterns of alcohol intake in this cohort suggest a lower average alcohol intake compared to more recent national averages for the same demographic group. Sample sizes were small for some subgroups, resulting in limited power to examine specific beverage types in different phases of the menstrual cycle, or to assess interaction. In addition, the influence of male partner alcohol intake was not assessed, the data relied on self-report, and residual confounding (e.g. unmeasured behaviors correlated with alcohol intake) is a possibility.

WIDER IMPLICATIONS OF THE FINDINGS

Results suggest an inverse association between alcohol and fecundability, and support the relevance of menstrual cycle phases in this link. More specifically, moderate to heavy drinking during the luteal phase, and heavy drinking in the ovulatory window, could disturb the delicate sequence of hormonal events, affecting chances of a successful conception.

STUDY FUNDING/COMPETING INTEREST(S)

Authors declare no conflict of interest. This work was supported by the National Institutes of Health grant, R01-HD24618.

TRIAL REGISTRATION NUMBER

N/A.

Comparison of frozen-thawed embryo transfer protocols in patients with previous cycle cancellation due to uterine peristalsis: a pilot study

Background/aim

To investigate the optimal protocol for frozen-thawed embryo transfer (FET) cycles in patients who previously had a cycle cancellation due to uterine peristalsis (UP).

Materials and methods

Thirty-four patients with previous embryo transfer (ET) cancellation due to UP during artificial cycle (AC) were included retrospectively. In the proceeding cycle, endometrium was prepared with AC (n: 23) in AC-FET group or with stimulated cycle that contains letrozole (L) (n: 11) in L-FET group. Intravenous bolus dose of 6.75 mg atosiban (Tractocile; Ferring Pharmaceuticals, Switzerland) injection was performed to all patients of AC-FET group due to UP ≥ 4/min on the planned ET day of proceeding cycle. Atosiban was not used in L-FET group. Primary outcome was live birth rate (LBR) per ET. Secondary outcomes were clinical pregnancy rate (CPR) per ET, implantation rate (IR), cycle cancellation rate.

Results

The baseline characteristics such as age, body mass index, antral follicle count, duration of infertility, and the number of prior in vitro fertilization attempts of each group were similar. The IR, CPR per ET, LBR per ET, CPR per cycle and LBR per cycle were significantly higher; cycle cancellation rates were significantly lower in L-FET group as compared to the AC-FET group.

Conclusion

Endometrial preparation with letrozole significantly improves CPR and LBR in FET cycles of patients with previous cycle cancellations due to UP.

Supraphysiological estradiol levels on the hCG trigger day are associated with SGA for singletons born from fresh embryo transfer

The effects of supraphysiological estradiol (E2) on neonatal outcomes and the significance of specific E2 concentrations remain unclear. The purpose of this study was to investigate whether supraphysiological E2 levels on the human chorionic gonadotropin (hCG) trigger day are associated with small size for gestational age (SGA) in singletons born from fresh embryo transfer (ET) cycles. Patients with singleton pregnancies who delivered after the transfer of fresh embryos, during the period from July 2012 to December 2017, at our center were included. We excluded cycles involving a vanishing twin, maternal age >35 years, basal follicle-stimulating hormone ≥10 mIU/ml, or anti-Müllerian hormone ≤1 ng/ml. We then divided all cycles into five groups by E2 level on trigger day: group A, <2000 pg/ml (reference group); group B, 2000 pg/ml≤E2<2999 pg/ml; group C, 3000 pg/ml≤E2<3999 pg/ml; group D, 4000 pg/ml≤E2<4999 pg/ml; and group E, ≥5000 pg/ml. The prevalence of SGA among singletons from fresh ET was the primary outcome. The SGA rate significantly increased when the E2 level was ≥4000 pg/ml, as observed by comparing groups D (odds ratio [OR]: 1·79, 95% confidence interval [CI]: 1·16-2·76, P = 0·01) and E (OR: 1·68, 95% CI: 1·10-2·56, P = 0·02) with the reference group. Multivariate logistic regression indicated that a serum E2 level of at least 4000 pg/ml on the hCG trigger day was associated with increased SGA and with significant differences for groups D (adjusted OR [AOR]: 1·65, 95% CI: 1·05-2·59, P = 0·03) and E (AOR: 1·60, 95% CI: 1·03-2·53, P = 0·04) relative to the reference group. In conclusion, in fresh ET cycles, the supraphysiological E2 ≥4000 pg/ml on the hCG trigger day increases the risk of SGA.

GnRH agonist in association with hCG versus hCG alone for final oocyte maturation triggering in GnRH antagonist cycles

Objective:

To analyze gonadotropin-releasing hormone (GnRH) agonist in association with human chorionic gonadotropin (hCG) (dual triggering) versus hCG alone (conventional triggering) for final oocyte maturation triggering in GnRH antagonist cycles in an unselected population of Brazilian women.

Methods:

This prospective case-control study involved 114 patients referred to autologous in vitro fertilization treatment between February 2018 and August 2019, recruited regardless of age, infertility factor or number of cycles. The patients were randomly allocated into two groups according to oocyte maturation triggering approach: group A (n = 48) - hCG only; and group B (n = 66) - hCG plus GnRH agonist. The main outcomes measured were the number of total and metaphase II (MII) oocytes retrieved.

Results:

The groups were homogenous in terms of age. There were no moderate or severe ovarian hyperstimulation syndrome events. There were no statistical differences concerning total or MII oocytes retrieved between the groups (p > 0.05). The MII/total oocyte rate was 70.9% in group A, and 74.5% in group B (p = 0.679). There was no oocyte retrieved in 2/48 patients (4.16%) in group A, 1/66 (1.5%) in group B. There were no MII oocytes in 4/48 patients (8.3%) in group A, and 2/66 (3%) in group B. Age was directly correlated to the number of total and MII oocytes retrieved (p < 0.05).

Conclusions:

Dual triggering was equivalent to conventional hCH triggering in terms of the number of total and MII oocytes retrieved in the general population. Further studies are necessary to ascertain dual triggering indication in selected groups of women.

Does the elevated estradiol level on the day of human chorionic gonadotropin administration affect embryo quality among women undergoing in vitro fertilization?

OBJECTIVE

To evaluate the association between estradiol (E2 ) levels on the day of human chorionic gonadotropin (hCG) administration and embryo quality during in vitro fertilization (IVF) cycles.

METHODS

A retrospective study of 6676 IVF cycles among women treated at the Reproductive Center of The First Affiliated Hospital of USTC, Hefei, China, from June 2014 to May 2017. E2 levels on hCG day were divided into four groups by 25th percentile: 0-1763 pg/mL (group I), 1763-3692 pg/mL (group II), 3692-4800 pg/mL (group III), and higher than 4800 pg/mL (group IV). Analysis of variance and multiple linear regression were used to test associations.

RESULTS

There were significant differences in the frequency of high-quality embryos between group I (51.6 ± 1.1%) and groups II (65.6 ± 0.8%), III (62.1 ± 0.7%), and IV (62.3 ± 0.7%). Using E2 as a dummy variable and group II as a control, multiple linear regression showed that E2 levels were associated with the frequency of high-quality embryos obtained (P < 0.05).

CONCLUSION

Serum E2 on hCG day had an impact on embryo quality. Higher E2 levels did not produce the most high-quality embryos; the highest frequencies were achieved for E2 levels within 1763-3692 pg/mL.

Patterns of sex hormone receptor expression in stimulated endometrium from oocyte donors

In patients with high serum E₂ embryo transfer is often postponed, as high E₂ levels adversely affect embryo transfer outcome. We aimed to determine if stratified serum oestradiol (E₂) and progesterone (P₄) levels differentially affect endometrial histology and endometrial oestrogen and progesterone receptor protein levels. Endometrial biopsies were collected from oocyte donors. Samples were divided based on peak serum E₂ levels into three groups: (i) low-E₂ (n = 33) E₂≤2999pg/mL; (ii) mid-E₂ (n = 40) E₂ 3000-4999 pg/mL; and (iii) high-E₂ (n = 15) E₂≥5000 pg/mL. Oestrogen receptor alpha (ERα) and progesterone receptors A and B (PR) protein levels in endometrial stroma (S), glandular (GE) and luminal (LE) epithelia were assessed by immunohistochemistry. Samples in high-E₂ group demonstrated strongest association with accelerated endometrial maturation (2 (1-2); 2 (1-3); and 3 (2.8-3) median days of advancement of endometrial maturation respectively in low, mid, high-E₂ groups, p = 0.046). There were significant differences in ERα and PR immunoexpression in S, GE and LE among the groups (p < 0.05). Higher E₂ levels were associated with decreased ERα expression (p < 0.017) in GE and LE, and increased PR expression in S and GE (p < 0.011 and p < 0.0001, respectively). Higher serum E₂ levels were associated with impaired endometrial steroid hormone receptor expression, higher serum P₄ and more advancement of endometrial maturation.

High levels estradiol affect blastocyst implantation and post-implantation development directly in mice

Background

Previous studies have demonstrated that high levels of estradiol (E2) impair blastocyst implantation through effects on the endometrium; however, whether high E2 directly affects blastocysts is not well established. The present study sought to clarify the direct impacts of high E2 levels on blastocysts in vitro.

Methods

ICR virgin albino mice were used. Using an in-vitro 8-day blastocyst culture model, immunofluorescence staining for the estrogen receptor (ER), blastocyst outgrowth assays, differential staining and TUNEL assays of blastocysts, and embryo transfer, we investigated the main outcomes of exposure to different E2 concentrations (10⁻⁷ to 10⁻⁴ M) in vitro and in vivo.

Results

ERα and ERβ expression were detected in pre-implantation stage embryos. In vitro exposure of blastocysts to 10⁻⁴ M E2 for 24 h followed by 7 days culture in the absence of E2 caused severe inhibition of implantation and post-implantation development. The late adverse effects of E2 on post-implantation development still occurred at concentrations of 10⁻⁷ to 10⁻⁵ M. In addition, blastocyst proliferation was reduced and apoptotic cells were increased following exposure to 10⁻⁴ M E2. Using an in vivo embryo-transfer model, we also showed that treatment with high E2 resulted in fewer implantation sites (38% vs. 72% in control) and greater resorption of implanted blastocysts (81% vs. 38% in control).

Conclusion

Exposure to high E2 concentrations in vitro is deleterious to blastocyst implantation and early post-implantation development, mainly owing to direct impacts of E2 on implanting blastocysts. In clinical assisted reproductive technique (ART), high serum E2 concentrations not only affects the endometrium, but also affects blastocysts directly at the period of implantation.

Embryo implantation in the laboratory: an update on current techniques

BACKGROUND

The embryo implantation process is crucial for the correct establishment and progress of pregnancy. During implantation, the blastocyst trophectoderm cells attach to the epithelium of the endometrium, triggering intense cell-to-cell crosstalk that leads to trophoblast outgrowth, invasion of the endometrial tissue, and formation of the placenta. However, this process, which is vital for embryo and foetal development in utero, is still elusive to experimentation because of its inaccessibility. Experimental implantation is cumbersome and impractical in adult animal models and is inconceivable in humans.

OBJECTIVE AND RATIONALE

A number of custom experimental solutions have been proposed to recreate different stages of the implantation process in vitro, by combining a human embryo (or a human embryo surrogate) and endometrial cells (or a surrogate for the endometrial tissue). In vitro models allow rapid high-throughput interrogation of embryos and cells, and efficient screening of molecules, such as cytokines, drugs, or transcription factors, that control embryo implantation and the receptivity of the endometrium. However, the broad selection of available in vitro systems makes it complicated to decide which system best fits the needs of a specific experiment or scientific question. To orient the reader, this review will explore the experimental options proposed in the literature, and classify them into amenable categories based on the embryo/cell pairs employed.The goal is to give an overview of the tools available to study the complex process of human embryo implantation, and explain the differences between them, including the advantages and disadvantages of each system.

SEARCH METHODS

We performed a comprehensive review of the literature to come up with different categories that mimic the different stages of embryo implantation in vitro, ranging from initial blastocyst apposition to later stages of trophoblast invasion or gastrulation. We will also review recent breakthrough advances on stem cells and organoids, assembling embryo-like structures and endometrial tissues.

OUTCOMES

We highlight the most relevant systems and describe the most significant experiments. We focus on in vitro systems that have contributed to the study of human reproduction by discovering molecules that control implantation, including hormones, signalling molecules, transcription factors and cytokines.

WIDER IMPLICATIONS

The momentum of this field is growing thanks to the use of stem cells to build embryo-like structures and endometrial tissues, and the use of bioengineering to extend the life of embryos in culture. We propose to merge bioengineering methods derived from the fields of stem cells and reproduction to develop new systems covering a wider window of the implantation process.

The Development of Nomograms to Predict Blastulation Rate Following Cycles of In Vitro Fertilization in Patients With Tubal Factor Infertility, Polycystic Ovary Syndrome, or Endometriosis

It is well known that the transfer of embryos at the blastocyst stage is superior to the transfer of embryos at the cleavage stage in many respects. However, the rate of blastocyst formation remains low in clinical practice. To reduce the possibility of wasting embryos and to accurately predict the possibility of blastocyst formation, we constructed a nomogram based on range of clinical characteristics to predict blastocyst formation rates in patients with different types of infertility. We divided patients into three groups based on female etiology: a tubal factor group, a polycystic ovary syndrome group, and an endometriosis group. Multiple logistic regression was used to analyze the relationship between patient characteristics and blastocyst formation. Each group of patients was divided into a training set and a validation set. The training set was used to construct the nomogram, while the validation set was used to test the performance of the model by using discrimination and calibration. The area under the curve (AUC) for the three groups indicated that the models performed fairly and that calibration was acceptable in each model.

Is There Any Association Between the Number of Oocytes Retrieved, Women Age, and Embryo Development?

While most studies focused on the association between the number of oocytes retrieved and LBR, there is lack of analysis highlighting the effect of the number of oocyte retrieved on top quality embryo (TQE) rate in different age groups. We aimed to study the correlations between the number and ratio of TQE, as assessed by morphology only, according to the number of oocytes retrieved, and to evaluate the impact of patients' age. This was a retrospective study that includes 1639 patients who underwent 2263 IVF cycles between 2016 and 2019. Patients were categorized into four groups according to the number of oocytes retrieved: 1-3, 4-9, 10-14, or > 15 oocytes (OPU groups A-D, respectively). Another classification was according to patient's age < 35, 35-40, and > 40 years. Morphologically, TQE (both cleavage stage and blastocyst) was defined as those eligible for transfer or vitrification. TQE was assessed both as a fraction of oocytes retrieved per patients (rate) and the average TQE per number oocytes retrieved category. For all age subgroups, a negative significant association was observed between the number of oocytes retrieved and TQE rate (56.1%, 43.6%, 35.9%, and 34.3% for groups A-D, respectively). The reduction was significant up to 14 oocytes retrieved and plateau thereafter. On the other hand, TQE rate was significantly increased as women age increased, from 36.1% TQE rate in young women (< 35 years) to 40.3% for 35-40 years to 42.5% in older patients (> 40 years). Finally, a linear regression revealed a drop in TQE rate of - 0.5% for every oocyte retrieved, while an increased in TQE rate of + 0.7%, as the women age increased by 1 year. While young women are able to recruit more oocyte, including medium/low quality, older women recruit less oocytes, with good quality, as demonstrated by their higher morphologically TQE rate relative to the number of oocyte retrieved.

Female age is associated with the optimal number of oocytes to maximize fresh live birth rates: an analysis of 256,643 fresh ART cycles

RESEARCH QUESTION

What is the optimal number of oocytes retrieved at which maximum live birth rate is observed after fresh autologous assisted reproductive technology (ART) cycles for women of different ages?

DESIGN

Retrospective cohort study of all fresh autologous ART aspiration cycles (n = 256,643) undertaken in Australia and New Zealand between 2009 and 2015. Primary outcome measure was live birth rate (LBR) (delivery of at least one liveborn baby at 20 weeks' gestation or over per fresh aspiration cycle). Cycles were grouped according to female age (<30, 30-34, 35-49, 40-44 and ≥45 years) and ovarian response (one to three, four to nine, 10-14, 15-19, 20-25 and ≥25 oocytes). Secondary outcome was incidence of ovarian hyperstimulation syndrome (OHSS) requiring hospitalization.

RESULTS

At different oocyte yields, LBR per fresh aspiration cycle peaked and then declined at, depending on female age: <30 years: six to 11 oocytes (LBR 31-34%); 30-34 years: 11-16 oocytes (LBR 29-30%); 35-39 years: nine to 17 oocytes (LBR 21-24%); and 40-44 years: 15-17 oocytes (LBR 11-12%). The incidence of OHSS increased significantly with the number of oocytes retrieved, from 1.2% with 15 oocytes retrieved to 9.3% with 30 or more oocytes retrieved (P < 0.001).

CONCLUSION

The optimal number of oocytes at which maximum LBR was observed in a fresh aspiration cycle was highly dependent on age. Because of the observational nature of the results, a cause-effect relationship between the number of oocytes retrieved and LBR should not be assumed; evidence from well-designed randomized control trials is required before clinical advice can be suggested.

Is there an optimal number of oocytes retrieved at which live birth rates or cumulative live birth rates per aspiration are maximized after ART? A systematic review

The association between the number of oocytes retrieved and fresh live birth rate (LBR) or cumulative LBR (CLBR), and whether an optimal number of oocytes are retrieved when LBR or CLBR are maximized, are highly relevant clinical questions; however published results are conflicting. A systematic review of all eligible studies (n = 16) published until January 2020 on MEDLINE, Embase, Scopus, CINAHL and Web of Science was conducted. Five studies evaluated only LBR from fresh cycles, five studies evaluated only CLBR from stimulated cycles and six evaluated both. A marked difference was observed between the oocyte yields at which LBR and CLBR were reportedly maximized in the individual studies. On the basis of nine studies, the optimal number of oocytes at which fresh LBR seems to be maximized is proposed to be between 12 and 18 oocytes (15 oocytes was the most common suggestion). On the other hand, CLBR continues to increase with the number of oocytes retrieved. This is the first systematic review on the topic, and it suggests that the retrieval of 12-18 oocytes is associated with maximal fresh LBR, whereas a continuing positive association is present between the number of oocytes retrieved and CLBR.

Effect of Triclosan Exposure on Developmental Competence in Parthenogenetic Porcine Embryo during Preimplantation

Triclosan (TCS) is included in various healthcare products because of its antimicrobial activity; therefore, many humans are exposed to TCS daily. While detrimental effects of TCS exposure have been reported in various species and cell types, the effects of TCS exposure on early embryonic development are largely unknown. The aim of this study was to determine if TCS exerts toxic effects during early embryonic development using porcine parthenogenetic embryos in vitro. Porcine parthenogenetic embryos were cultured in in vitro culture medium with 50 or 100 µM TCS for 6 days. Developmental parameters including cleavage and blastocyst formation rates, developmental kinetics, and the number of blastomeres were assessed. To determine the toxic effects of TCS, apoptosis, oxidative stress, and mitochondrial dysfunction were assessed. TCS exposure resulted in a significant decrease in 2-cell rate and blastocyst formation rate, as well as number of blastomeres, but not in the cleavage rate. TCS also increased the number of apoptotic blastomeres and the production of reactive oxygen species. Finally, TCS treatment resulted in a diffuse distribution of mitochondria and decreased the mitochondrial membrane potential. Our results showed that TCS exposure impaired porcine early embryonic development by inducing DNA damage, oxidative stress, and mitochondrial dysfunction.

Uterine Gpr83 mRNA is highly expressed during early pregnancy and GPR83 mediates the actions of PEN in endometrial and non-endometrial cells

OBJECTIVE

To characterize the expression and signaling of uterine GPR83 in vivo in the nonpregnant and pregnant mouse and in vitro in human endometrial and nonendometrial cells.

DESIGN

Controlled laboratory study.

SETTING

Not applicable.

PATIENTS

Not applicable.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Expression of uterine Gpr83 was determined by quantitative polymerase chain reaction throughout the estrous cycle and during early pregnancy in ovarian-stimulated and non-ovarian-stimulated mice and pregnant and pseudopregnant mice. Expression was also determined in ovariectomized mice after the administration of oil, E2, P4, or E2 + P4 and in stromal cells following 6 days of in vitro decidualization. GPR83 signaling was studied in human endometrial and embryonic kidney cell lines. Cells were treated by PEN, a GPR83 ligand, and PEN-induced extracellular signal-regulated kinase (ERK) phosphorylation was assayed under conditions that blocked Gα_q/11 and/or β-arrestin signaling.

RESULTS

Uterine Gpr83 is expressed throughout the estrous cycle and during early pregnancy; expression increases dramatically at the time of uterine receptivity, embryo implantation, and stromal cell decidualization. In the ovariectomized mouse, hormone add-back reveals that Gpr83 expression is highly responsive to the combined treatment of E2 and P4, and studies in the ovarian-stimulated mouse show that expression is also very sensitive to changes in E2 and P4 and is therefore tightly regulated by E2 and P4. At the implantation site, expression is elevated up to D6 of pregnancy and then declines rapidly on D7 and D8, suggesting that if there is any involvement in decidualization, it is likely associated with primary but not secondary stromal cell decidualization. This premise was supported by the observation that stromal cell decidualization in vitro progresses with a decline in Gpr83 expression. In ERα/PR-expressing endometrial Ishikawa cells, GPR83 mediates PEN signals in a Gα_q/11-dependent manner, and studies conducted in HEK 293 cells lacking β-arrestin revealed that GPR83 also signals via a β-arrestin-dependent manner. When signaling by either one or both pathways is downregulated, cells exhibit a major reduction in responsiveness to PEN treatment, demonstrating that signaling by both pathways is significant.

CONCLUSION

We hypothesize that PEN/GPR83 signaling regulates uterine receptivity, embryo implantation, and primary stromal cell decidualization by coupling to Gα_q/11- and β-arrestin-dependent pathways.

Effect of embryo stage at transfer on placental histopathology features in singleton live births resulting from fresh embryo transfers

OBJECTIVE

To evaluate the effect of embryo stage at transfer on placental histopathology and perinatal outcome in singleton live births resulting from fresh embryo transfers (ETs).

DESIGN

Retrospective cohort study.

SETTING

Not applicable.

PATIENT(S)

The study population included all live births after fresh ETs during the period from 2009 to 2017.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Primary outcomes included anatomic, inflammatory, vascular malperfusion, and villous maturation placental features. Secondary outcomes included fetal, maternal, and perinatal complications.

RESULT(S)

A total of 677 live births were included in the final analysis and were allocated to the cleavage-stage (n = 252) and blastocyst (n = 425) ET groups. After the adjustment for confounding factors, the blastocyst group was found to be associated with a higher incidence of circummarginate membranes insertion (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.2-3.4), delayed villous maturation (OR 8.5, 95% CI 1.2-69.3), chorangiosis (OR 2.0, 95% CI 1.2-3.8), parenchymal calcifications (OR 10.6, 95% CI 1.4-80.2), and intrapartum nonreassuring fetal heart rate tracing (OR 2.4, 95% CI 1.3-4.5). Compared with cleavage-stage ETs, live births resulting from the blastocysts were associated with a lower incidence of velamentous cord insertion (OR 0.5, 95% CI 0.3-0.9), retroplacental hematoma (OR 0.3, 95% CI 0.1-0.8), subchorionic thrombi (OR 0.3, 95% CI 0.1-0.8), and avascular villi (OR 0.2, 95% CI 0.03-0.7).

CONCLUSION(S)

Live births resulting from fresh cleavage-stage and blastocyst ETs have different placental histopathology features, with a higher rate of intrapartum nonreassuring fetal heart rate tracing in the blastocyst group.

Effect of ovarian stimulation on the expression of piRNA pathway proteins

PIWI-interacting RNAs (piRNAs) play an important role in gametogenesis, fertility and embryonic development. The current study investigated the effect of different doses of pregnant mare serum gonadotrophin/human chorionic gonadotrophin (PMSG/hCG) and repeated ovarian stimulation (OS) on the expression of the Mili, Miwi, Mael, Tdrd1, Tdrd9, qnd Mitopld genes, which have crucial roles in the biogenesis and function of piRNAs. Here, we found that after treatment with 7.5 I.U. PMSG/hCG and two repeated rounds of OS, both the mRNA and protein levels of Tdrd9, Tdrd1 and Mael showed the greatest decrease in the ovarian tissue, but the plasma E₂ levels showed the strongest increases (p<0.05). However, we found that the Mitopld, Miwi and Mili gene levels were decreased significantly after treatment with 12.5 I.U. PMSG/hCG. Our results suggested that exogenous gonadotropin administration leads to a significant decrease in the expression of the Mili, Miwi, Mael, Tdrd1, Tdrd9 and Mitopld genes, which are critically important in the piRNA pathway, and the changes in the expression levels of Tdrd9, Tdrd1 and Mael may be associated with plasma E₂ levels. New comprehensive studies are needed to reduce the potential effects of OS on the piRNA pathway, which silences transposable elements and maintains genome integrity, and to contribute to the safety of OS.

Gonadotropin-releasing hormone agonist for ovulation trigger - OHSS prevention and use of modified luteal phase support for fresh embryo transfer

The introduction of gonadotrophin-releasing hormone agonist (GnRHa) trigger greatly impacted modern IVF treatment. Patients at low risk of ovarian hyperstimulation syndrome (OHSS) development, undergoing fresh embryo transfer and GnRHa trigger can be offered a virtually OHSS-free treatment with non-inferior reproductive outcomes by using a modified luteal phase support in terms of small boluses of human chorionic gonadotrophin (hCG), daily recombinant luteinizing hormone LH (rLH) or GnRHa. In the OHSS risk patient, GnRHa trigger can safely be performed, followed by a 'freeze-all' policy with a minimal risk of OHSS development and high live birth rates in the subsequent frozen embryo transfer cycle. Importantly, GnRHa trigger opened the 'black box' of the luteal phase, promoting research in the most optimal steroid levels during the luteal phase. GnRHa trigger allows high-dose gonadotropin stimulation to achieve the optimal number of oocytes and embryos needed to ensure the highest chance of live birth. This review thoroughly discusses how the GnRHa trigger concept adds safety and efficacy to modern IVF in terms of OHSS prevention. Furthermore, the optimal luteal phase management after GnRHa trigger in fresh embryo transfer cycles is discussed.

No effect of ovarian stimulation and oocyte yield on euploidy and live birth rates: an analysis of 12 298 trophectoderm biopsies

STUDY QUESTION

Does ovarian stimulation affect embryo euploidy rates or live birth rates (LBRs) after transfer of euploid embryos?

SUMMARY ANSWER

Euploidy rates and LBRs after transfer of euploid embryos are not significantly influenced by gonadotropin dosage, duration of ovarian stimulation, estradiol level, follicle size at ovulation trigger or number of oocytes retrieved, regardless of a woman’s age.

WHAT IS KNOWN ALREADY

Aneuploidy rates increase steadily with age, reaching &gt;80% in women &gt;42 years old. The goal of ovarian stimulation is to overcome this high aneuploidy rate through the recruitment of several follicles, which increases the likelihood of obtaining a euploid embryo that results in a healthy conceptus. However, several studies have suggested that a high response to stimulation might be embryotoxic and/or increase aneuploidy rates by enhancing abnormal segregation of chromosomes during meiosis. Furthermore, a recent study demonstrated a remarkable difference in euploidy rates, ranging from 39.5 to 82.5%, among young oocyte donors in 42 fertility centres, potentially suggesting an iatrogenic etiology resulting from different stimulation methods.

STUDY DESIGN, SIZE, DURATION

This is a retrospective cohort study that included 2230 in vitro fertilisation (IVF) with preimplantation genetic testing for aneuploidy (PGT-A) cycles and 930 frozen-thawed single euploid embryo transfer (FET) cycles, performed in our centre between 2013 and 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 12 298 embryos were analysed for ploidy status. Women were divided into five age groups (&lt;35, 35–37, 38–40, 41–42 and &gt;42 years old). Outcomes were compared between different durations of stimulation (&lt;10, 10–12 and ≥13 days), total gonadotropin dosages (&lt;4000, 4000–6000 and &gt;6000 IU), numbers of oocytes retrieved (&lt;10, 10–19 and ≥20 oocytes), peak estradiol levels (&lt;2000, 2000–3000 and &gt;3000 pg/mL), and sizes of the largest follicle on the day of trigger (&lt;20 and ≥20 mm).

MAIN RESULTS AND THE ROLE OF CHANCE

Within the same age group, both euploidy rates and LBRs were comparable between cycles regardless of their differences in total gonadotropin dosage, duration of stimulation, number of oocytes harvested, size of the largest follicles or peak estradiol levels. In the youngest group, (&lt;35 years, n = 3469 embryos), euploidy rates were comparable between cycles with various total gonadotropin dosages (55.6% for &lt;4000 IU, 52.9% for 4000–6000 IU and 62.3% for &gt;6000 IU; P = 0.3), durations of stimulation (54.4% for &lt;10 days, 55.2% for 10–12 days and 60.9% for &gt;12 days; P = 0.2), number of oocytes harvested (59.4% for &lt;10 oocytes, 55.2% for 10–19 oocytes and 53.4% for ≥20 oocytes; P = 0.2), peak estradiol levels (55.7% for E2 &lt; 2000 pg/mL, 55.4% for E2 2000–3000 pg/mL and 54.8% for E2 &gt; 3000 pg/mL; P = 0.9) and sizes of the largest follicle (55.6% for follicles &lt;20 mm and 55.1% for follicles ≥20 mm; P = 0.8). Similarly, in the oldest group (&gt;42 years, n = 1157 embryos), euploidy rates ranged from 8.7% for gonadotropins &lt;4000 IU to 5.1% for gonadotropins &gt;6000 IU (P = 0.3), from 10.8% for &lt;10 days of stimulation to 8.5% for &gt;12 days of stimulation (P = 0.3), from 7.3% for &lt;10 oocytes to 7.4% for ≥20 oocytes (P = 0.4), from 8.8% for E2 &lt; 2000 pg/mL to 7.5% for E2 &gt; 3000 pg/mL (P = 0.8) and from 8.2% for the largest follicle &lt;20 mm to 8.9% for ≥20 mm (P = 0.7). LBRs after single FET were also comparable between these groups.

LIMITATIONS, REASONS FOR CAUTION

Although this large study (2230 IVF/PGT-A cycles, 12 298 embryos and 930 single FET cycles) demonstrates the safety of ovarian stimulation in terms of aneuploidy and implantation potential of euploid embryos, a multi-centre study may help to prove the generalisability of our single-centre data.

WIDER IMPLICATIONS OF THE FINDINGS

These findings reassure providers and patients that gonadotropin dosage, duration of ovarian stimulation, estradiol level, follicle size at ovulation trigger and number of oocytes retrieved, within certain ranges, do not appear to significantly influence euploidy rates or LBRs, regardless of the woman’s age.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received and there are no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A

Uterine aquaporin expression is dynamically regulated by estradiol and progesterone and ovarian stimulation disrupts embryo implantation without affecting luminal closure

The study investigated the effect of normal and supraphysiological (resulting from gonadotropin-dependent ovarian stimulation) levels of estradiol (E2) and progesterone (P4) on mouse uterine aquaporin gene/protein (Aqp/AQP) expression on Day 1 (D1) and D4 of pregnancy. The study also examined the effect of ovarian stimulation on uterine luminal closure and uterine receptivity on D4 of pregnancy and embryo implantation on D5 and D7 of pregnancy. These analyses revealed that the expression of Aqp3, Aqp4, Aqp5 and Aqp8 is induced by E2 while the expression of Aqp1 and Aqp11 is induced by P4. Additionally, P4 inhibits E2 induction of Aqp3 and Aqp4 expression while E2 inhibits Aqp1 and Aqp11 expression. Aqp9, however, is constitutively expressed. Ovarian stimulation disrupts Aqp3, Aqp5 and Aqp8 expression on D4 and AQP1, AQP3 and AQP5 spatial expression on both D1 and D4, strikingly so in the myometrium. Interestingly, while ovarian stimulation has no overt effect on luminal closure and uterine receptivity, it reduces implantation events, likely through a disruption in myometrial activity and embryo development. The wider implication of this study is that ovarian stimulation, which results in supraphysiological levels of E2 and P4 and changes (depending on the degree of stimulation) in the E2:P4 ratio, triggers abnormal expression of uterine AQP during pregnancy, and this is associated with implantation failure. These findings lead us to recognize that abnormal expression would also occur under any pathological state (such as endometriosis) that is associated with changes in the normal E2:P4 ratio. Thus, infertility among these patients might in part be linked to abnormal uterine AQP expression.

Seasonal transfer and quantification of urinary estradiol in the big brown bat (Eptesicus fuscus)

Growing evidence shows that sex steroids not only act within the individual whose glands produce them; they can also act on proximate conspecifics. Previous studies show that exogenous 17β-estradiol (E₂) can be absorbed both nasally and percutaneously, arriving in blood, neural, reproductive, and peripheral tissues. When male bats were injected with radiolabeled E₂ (³H-E₂) and housed with females during the mating season, radioactivity was reliably measured in the females' tissues. The present study was designed to compare E₂ transfer from male to female bats at three time points in the annual reproductive cycle: spring (ovulation and fertilization), summer (maternal season), and autumn (mating season). Pairs of mature female bats were housed with a mature ³H-E₂-treated male (50 μCi). Following 48 h of communal housing, radioactivity was measured in the tissues of female bats. Higher levels of radioactivity were present in the uterus and other tissues during the spring and autumn seasons compared to the summer season. We also measured natural levels of bioactive, unconjugated E₂ in the urine of male bats using enzyme immunoassays, and found that it was present in all three seasons but at lower levels during the summer. Male-excreted E₂ could transfer to females within the close confines of a roost, potentially influencing their reproductive physiology and behavior. These results suggest increased E₂ transfer coincides with female reproduction, with urine as a likely vector. We suggest that sex steroid transfer among interacting individuals may explain several mammalian phenomena historically viewed as "pheromonal".

Ovarian stimulation for freeze-all IVF cycles: a systematic review

BACKGROUND

Freeze-all IVF cycles are becoming increasingly prevalent for a variety of clinical indications. However, the actual treatment objectives and preferred treatment regimens for freeze-all cycles have not been clearly established.

OBJECTIVE AND RATIONALE

We aimed to conduct a systematic review of all aspects of ovarian stimulation for freeze-all cycles.

SEARCH METHODS

A comprehensive search in Medline, Embase and The Cochrane Library was performed. The search strategy included keywords related to freeze-all, cycle segmentation, cumulative live birth rate, preimplantation genetic diagnosis, preimplantation genetic testing for aneuploidy, fertility preservation, oocyte donation and frozen-thawed embryo transfer. We included relevant studies published in English from 2000 to 2018.

OUTCOMES

Our search generated 3292 records. Overall, 69 articles were included in the final review. Good-quality evidence indicates that in freeze-all cycles the cumulative live birth rate increases as the number of oocytes retrieved increases. Although the risk of severe ovarian hyperstimulation syndrome (OHSS) is virtually eliminated in freeze-all cycles, there are certain risks associated with retrieval of large oocyte cohorts. Therefore, ovarian stimulation should be planned to yield between 15 and 20 oocytes. The early follicular phase is currently the preferred starting point for ovarian stimulation, although luteal phase stimulation can be used if necessary. The improved safety associated with the GnRH antagonist regimen makes it the regimen of choice for ovarian stimulation in freeze-all cycles. Ovulation triggering with a GnRH agonist almost completely eliminates the risk of OHSS without affecting oocyte and embryo quality and is therefore the trigger of choice. The addition of low-dose hCG in a dual trigger has been suggested to improve oocyte and embryo quality, but further research in freeze-all cycles is required. Moderate-quality evidence indicates that in freeze-all cycles, a moderate delay of 2–3 days in ovulation triggering may result in the retrieval of an increased number of mature oocytes without impairing the pregnancy rate. There are no high-quality studies evaluating the effects of sustained supraphysiological estradiol (E2) levels on the safety and efficacy of freeze-all cycles. However, no significant adverse effects have been described. There is conflicting evidence regarding the effect of late follicular progesterone elevation in freeze-all cycles.

WIDER IMPLICATIONS

Ovarian stimulation for freeze-all cycles is different in many aspects from conventional stimulation for fresh IVF cycles. Optimisation of ovarian stimulation for freeze-all cycles should result in enhanced treatment safety along with improved cumulative live birth rates and should become the focus of future studies.

Association between serum estradiol level on the human chorionic gonadotrophin administration day and clinical outcome

BACKGROUND

Estradiol, as an important hormone in follicular development and endometrial receptivity, is closely related to clinical outcomes of fresh in vitro fertilization embryo transfer (IVF-ET) cycles. The aim of this retrospective study was to evaluate the association between elevated serum estradiol (E2) levels on the day of human chorionic gonadotrophin (hCG) administration and IVF-ET pregnancy and birth outcomes.

METHODS

A total of 1771 infertile patients with their first fresh IVF-ET cycles were analyzed retrospectively between January 2011 and January 2016 in Peking University First Hospital. Patients were categorized by serum E2 levels on the day of hCG administration into six groups: group 1 (serum E2 levels ≤ 1000 pg/mL, n = 205), group 2 (serum E2 levels 1001-2000 pg/mL, n = 457), group 3 (serum E2 levels 2001-3000 pg/mL, n = 425), group 4 (serum E2 levels 3001-4000 pg/mL, n = 310), group 5 (serum E2 levels 4001-5000 pg/mL, n = 237), and group 6 (serum E2 levels > 5000 pg/mL, n = 137). The retrieved oocyte and MII oocyte numbers and implantation and clinical pregnancy rates of the groups were compared as the first objective of the study. For the 360 women with singleton births among all patients, the area under the corresponding receiver operating characteristic curve (ROC curve) was calculated to assess the predictive value of the E2 change for the probability of low birth weight (LBW) infants as the second objective.

RESULTS

The retrieved oocyte and MII oocyte numbers and implantation and clinical pregnancy rates gradually increased from groups 1 to 5 but decreased in group 6. The parameters of group 1 were statistically worse than those of the other groups, from group 2 to group 6 (the number of retrieved oocytes, t = 13.096, t = 23.307, t = 23.086, t = 26.376, t = 19.636, P < 0.003; the number of retrieved MII oocytes, t = 10.856, t = 20.868, t = 21.874, t = 23.374, t = 19.092, P < 0.003; the implantation rate, χ = 12.179, χ = 22.239, χ = 23.993, χ = 23.344, χ = 16.758, P < 0.003; the clinical pregnancy rate, χ = 16.415, χ = 28.074, χ = 35.387, χ = 37.025, χ = 24.590, P < 0.003). ROC analysis revealed that when a serum peak E2 of 3148 pg/mL was used to predict LBW.

CONCLUSIONS

The results indicate that serum E2 levels have a concentration-dependent effect on clinical outcomes. The optimal range of the E2 level during a fresh IVF-ET cycle is 1000 to 3148 pg/mL.

Factors predicting clinical pregnancy rate of in vitro fertilization-embryo transfer (a STROBE-compliant article)

The aim of this study was to investigate the factors predicting clinical pregnancy rate of in vitro fertilization-embryo transfer (IVF-ET).The data of 9960 patients receiving IVF-ET fresh cycle at our Reproductive Center from January 2009 to December 2017 were first divided into pregnant group and non-pregnant group to find the clinical pregnancy rate-related factors. According to the serum HCG levels at 36 hours and 12 hours after HCG trigger, all patients were divided into 4 groups including <50 mIU/ml, ≥50 and <100 mIU/ml, ≥100 and <200 mIU/ml, and ≥200 mIU/ml groups to know whether the HCG levels at 36 hours and 12 hours affect the pregnancy rate. According to the serum HCG ratio at 36 hours to 12 hours (36 h/12 h) after HCG trigger, all patients were divided into three groups including <0.88, 0.88-1.06 and >1.06 groups to observe whether the serum HCG ratio (36 h/12 h) affects the clinical pregnancy rate. According to different assisted pregnancy modes, all patients were divided into 3 groups including IVF, ICSI, and IVF/ICSI groups to observe whether the assisted pregnancy mode affects the clinical pregnancy rate. The correlation of the clinical pregnancy rate with pregnancy rate-related factors obtained above was analyzed using logistic regression analysis model.The clinical pregnancy rate significantly increased (P < .01) in the HCG ratio (36 h/12 h) >1.06 group as compared with the HCG ratio (36 h/12 h) < 0.88 and 0.88-1.06 groups. The serum estrogen (E2) level at 36 hours was significantly lower and the number of retrieved oocytes was significantly higher in the HCG ratio (36 h/12 h) >1.06 group than in the HCG ratio (36 h/12 h) <0.88 and 0.88-1.06 groups (P = .000).The serum HCG ratio (36 h/12 h) may be used as a predictor of IVF-ET clinical pregnancy rate. High clinical pregnancy rate is probably associated with E2 down-regulation in the HCG ratio (36 h/12 h) >1.06 group.

Lipid Profiling of Peri-implantation Endometrium in Patients With Premature Progesterone Rise in the Late Follicular Phase

CONTEXT

Late follicular phase elevation in serum progesterone (P) during controlled ovarian hyperstimulation negatively affects the outcome of assisted reproductive technology by contributing to endometrial-embryo asynchrony. There are still no data on lipid metabolite alterations during this process.

OBJECTIVES

To investigate alterations in the lipid profile during the window of implantation in patients with premature P rise.

DESIGN

Lipidomic variations in the endometrium were evaluated by ultrahigh-performance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry.

SETTING

University assisted reproductive medicine unit.

PATIENTS OR OTHER PARTICIPANTS

Forty-three patients undergoing in vitro fertilization/intracytoplasmic sperm injection because of a tubal factor or male factor infertility were included in this study. The patients were divided into a high P group (P ≥ 1.5 ng/mL, 15 patients) and a normal P group (P < 1.5 ng/mL, 28 patients) on the day of human chorionic gonadotropin administration.

INTERVENTIONS

The endometrial tissues were obtained by Pipelle biopsy 7 days after human chorionic gonadotropin administration.

MAIN OUTCOME MEASURES

Alterations in lipid metabolites.

RESULTS

A total of 1026 ions were identified, and 25 lipids were significantly upregulated. The endometrial lipid profile was characterized by substantial increases in the concentrations of phosphatidylcholine, phosphatidylethanolamine, lysophosphatidylcholine, diacylglycerol, ceramide, phosphatidylinositol, and phosphatidylserine in patients with a premature P rise at the end of the follicular phase. The correlation analysis between P levels and lipids showed a stronger negative correlation between phosphatidylethanolamine or phosphatidylserine and P levels.

CONCLUSIONS

Premature P elevation disrupts the lipid homeostasis of the endometrium during the peri-implantation period. The altered lipid levels may impair endometrial receptivity and early embryo implantation.

Evaluation of uterine receptivity after gonadotropin releasing hormone agonist administration as an oocyte maturation trigger: a rodent model

In natural cycle or minimal stimulation cycle IVF, buserelin acetate (buserelin), a gonadotropin-releasing hormone agonist, is often used as a maturation trigger; however, its effect on pregnancy outcomes remains unclear. Therefore, in the present study, we compared uterine receptivity in buserelin-administered mice with that in human chorionic gonadotropin (hCG)-administered mice during the peri-implantation period. Implantation, decidualisation, and term-pregnancy were impaired following hCG, but not buserelin administration. hCG stimulated the synthesis and secretion of progesterone and oestradiol, whereas ovarian steroidogenesis in the buserelin-treated group was comparable with that in the control group. Furthermore, similar to the observation in controls, the buserelin-treated group exhibited activation of progesterone receptor signalling and inhibition of oestrogen receptor signalling in the endometrial epithelium on the day of implantation. However, epithelial progesterone signalling was not detected, and a high expression of genes downstream to oestrogen was observed on day 4 following hCG administration. These results suggest that buserelin administration does not impact uterine receptivity as it did not affect ovarian steroidogenesis and endometrial steroid signalling. Therefore, buserelin is preferred as an oocyte maturation trigger to optimise uterine receptivity during treatments involving timed intercourse, intrauterine insemination, or fresh embryo transfer following in vitro fertilisation.

Is there an association between oocyte number and embryo quality? A systematic review and meta-analysis

This systematic review and meta-analysis determined the association between aspirated after ovarian stimulation and top/good quality embryos obtained in women undergoing ovarian stimulation for IVF/intracytoplasmic sperm injection (ICSI). MEDLINE, EMBASE, Scopus, CINAHL and Web of Science were searched for English-language publications on top/good-quality embryos at cleavage (day 2/3) and/or blastocyst (day 5/6) developmental stages, up to 18 November 2017. Twenty-eight studies (three prospective and 25 retrospective) reporting data on 291,752 assisted reproductive technology (ART) cycles were considered eligible. We confirmed a strong positive association between oocytes retrieved and top/good-quality day 2/3 embryos (weighted correlation coefficient [r_w] = 0.791), day 5/6 embryos (r_w = 0.901), metaphase II oocytes (r_w = 0.988), oocytes exhibiting two pronuclei (r_w = 0.987) and euploid embryos (r_w = 0.851); P < 0.001 for all correlations (evaluated in subsets of the 17 studies). Data from 5657 cycles showed that the group with the most oocytes aspirated had the most top/good-quality day 2/3 embryos (pooled standardized mean differences (high [>15] versus low [<4] 1.91, 95% confidence interval [CI] 1.05-2.77, P < 0.0001; high versus medium [4-15] 1.15, 95% CI 0.74-1.55, P < 0.0001; medium versus low 1.41, 95% CI 0.79-2.03, P < 0.0001). Individual participant meta-analysis would enable accurate determination of these associations and other outcomes.

Oxytocin antagonism reverses the effects of high oestrogen levels and oxytocin on decidualization and cyclooxygenase activity in endometrial tissues

RESEARCH QUESTION

What is the in-vitro effect of oxytocin receptor (OTR) antagonism on parameters of receptivity in human endometrial explants and endometrial stromal cell lines cultured in oestradiol-rich conditions mimicking ovarian stimulation?

DESIGN

Experimental in-vitro study on endometrial tissue explants collected by aspiration biopsy from 30 women undergoing fertility treatment and cultured endometrial tHESC cell line. The study examined the effects of high oestradiol, oxytocin and OTR antagonist on parameters of decidualization (cell viability and prolactin secretion) as well as cyclooxygenase-1/2 (COX-1/2) activity and prostaglandin F_2α (PGF_2α) secretion. Changes in expression of OXTR and COX-2 genes were examined using quantitative polymerase chain reaction (qPCR).

RESULTS

In experiments on cultured endometrial cell line, high oestradiol and oxytocin similarly limited the viability of cells. In cultured endometrial explants both also decreased the secretion of prolactin (a marker of decidualization) and augmented endometrial COX-2 activity and formation of PGF_2α. Oxytocin antagonist atosiban was confirmed to reverse the above effects, both in the endometrial line and endometrial explants. Addition of atosiban to cultures acted analogously in experiments employing both oxytocin and high oestradiol.

CONCLUSIONS

Oxytocin antagonist reversed the effects of high oestradiol and oxytocin on parameters related to endometrial receptivity in conditions mimicking ovarian stimulation. This might point to a novel, endometrium-related mechanism to support embryo implantation achieved by the application of oxytocin antagonist prior to embryo transfer.