Parameters predicting the implantation rate of thawed IVF/ICSI embryos: a retrospective study

A proof of concept for a deep learning system that can aid embryologists in predicting blastocyst survival after thaw

The ability to understand whether embryos survive the thaw process is crucial to transferring competent embryos that can lead to pregnancy. The objective of this study was to develop a proof of concept deep learning model capable of assisting embryologist assessment of survival of thawed blastocysts prior to embryo transfer. A deep learning model was developed using 652 labeled time-lapse videos of freeze-thaw blastocysts. The model was evaluated against and along embryologists on a test set of 99 freeze-thaw blastocysts, using images obtained at 0.5 h increments from 0 to 3 h post-thaw. The model achieved AUCs of 0.869 (95% CI 0.789, 0.934) and 0.807 (95% CI 0.717, 0.886) and the embryologists achieved average AUCs of 0.829 (95% CI 0.747, 0.896) and 0.850 (95% CI 0.773, 0.908) at 2 h and 3 h, respectively. Combining embryologist predictions with model predictions resulted in a significant increase in AUC of 0.051 (95% CI 0.021, 0.083) at 2 h, and an equivalent increase in AUC of 0.010 (95% CI -0.018, 0.037) at 3 h. This study suggests that a deep learning model can predict in vitro blastocyst survival after thaw in aneuploid embryos. After correlation with clinical outcomes of transferred embryos, this model may help embryologists ascertain which embryos may have failed to survive the thaw process and increase the likelihood of pregnancy by preventing the transfer of non-viable embryos.

Does the outcome of fresh embryo transfer affect the outcome of subsequent thawed embryo transfers from sibling oocytes in patients that utilized all their embryos?

The association between fresh embryo transfer (ET) outcome and the subsequent frozen-thawed (FET) cycles that follow is not clear, mainly because of incomplete embryo cohort utilization. The aim of this study was to determine if the outcome of a fresh ET affects the frozen cumulative clinical pregnancy (CP) and live birth (LB) rates resulting from the utilization of all surplus embryos from sibling oocytes. Outcome measures were the FET cumulative CP and LB rates. Multivariate logistic regression was performed for the frozen cumulative CP rate and adjusted for age, the number of oocytes, fresh ET outcome and other confounders. A total of 1313 cycles met the inclusion criteria. The FET cumulative CP and LB rates were not affected by the outcome of the fresh ET. The FET cumulative CP rate increased with the number of oocytes collected regardless of whether a pregnancy was achieved in the fresh cycle or not. In multivariate analysis, age (OR = 0.96, 95% CI 0.94-0.98), protocol (OR = 0.13, 95% CI 0.03-0.57) and the number of oocytes (OR = 1.05, 95% CI 1.02-1.07) were associated with the frozen cumulative CP rate. It is concluded that fresh ET does not impact the outcome of the vitrified-thawed embryos from the same oocyte cohort.

The impact of blastomere loss on pregnancy and neonatal outcomes of vitrified-warmed Day3 embryos in single embryo transfer cycles

BACKGROUND

Blastomere loss is a common phenomenon that occurs following cryopreservation. To date, studies have drawn conflicting conclusions regarding the impact of blastomere loss on pregnancy outcomes. Besides, limited information is available concerning the neonatal safety of embryos with blastomere loss. In the present study, we aimed to investigate the impact of blastomere loss on pregnancy and neonatal outcomes of vitrified/warmed Day3 cleavage-stage embryos in single embryo transfer cycles.

METHODS

This retrospective cohort study included all vitrified/warmed D3 cleavage-stage single frozen-thawed embryo transfer (FET) cycles between April 2015 and February 2021. We compared pregnancy and subsequent neonatal outcomes between the intact embryos group and the blastomere loss group in single FET cycles.

RESULTS

A total of 6287 single FET cycles were included in the study, in which 5873 cycles were classified into the intact embryo group and 414 cycles were classified into the blastomere loss group. The outcomes of the blastomere loss group were significantly inferior to those of the intact embryo group, in terms of implantation/biochemical pregnancy/clinical pregnancy/ongoing pregnancy rate and live birth rate per embryo transfer cycle/per clinical pregnancy. Further binary logistic regression confirmed that blastomere loss was negatively associated with live birth. Moreover, the blastomere loss group presented with an elevated early miscarriage rate. The neonatal conditions were broadly similar between the two groups. Additionally, multiple binary logistic regression analysis demonstrated that primary infertility and intracytoplasmic sperm injection (ICSI) were common influencing factors of blastomere loss (aOR 1.447, 95% CI 1.038-2.019, P = 0.029; aOR: 1.388, 95% CI: 1.044-51.846, P = 0.024).

CONCLUSIONS

The transfer of vitrified/warmed D3 embryos with blastomere loss is related to impaired embryo developmental potentials and reduced probabilities of conception. Moreover, even if the embryos with blastomere loss have implanted and reached clinical pregnancies, they present with a lower possibility of developing to live birth owing to a higher early miscarriage rate. However, once the embryos with blastomere loss result in a live birth, no adverse neonatal outcomes are observed. Primary infertility and ICSI were found to be risk factors for blastomere loss.

Post-thaw culture has no beneficial effect on frozen embryos transfer outcomes comparing to same embryonal age non-cultured frozen-thawed embryos

PURPOSE

To assess the impact of post-thawing embryo culture on frozen embryo transfer (FET) outcomes.

METHODS

A retrospective cohort study including 678 consecutive FET cycles performed between the years 2004 and 2017 was conducted. Patients older than 45 years old were excluded. FET cycles were stratified as follows: (1) two-day (2d) embryos thawed and cultured to three-day (3d) versus 3d embryos thawed and transferred; (2) 2d or 3d embryos thawed and cultured to blastocysts versus blastocysts thawed and transferred. A p-value <.05 was considered statistically significant.

RESULTS

Maternal age, BMI, smoking, and basal FSH of the 2d and 3d cultured embryo group (n = 110) and the 3d non-cultured embryo group (n = 189) were comparable. Endometrium preparation protocols and the achieved endometrial thickness did not differ between groups. Pregnancy rate, implantation rate, clinical pregnancy, live birth rate, abortions, multiple pregnancies, perinatal outcomes, and birth weight were comparable.The 2d and 3d embryos cultured to blastocyst (n = 41) compared to non-cultured blastocyst (n = 338) showed that the non-cultured blastocyst patients had higher smoking rates and longer follicular phase. Endometrial thickness was comparable. The 2d and 3d embryos cultured to blastocyst stage had higher multiple pregnancies rate compared to the blastocyst non-cultured group, whereas pregnancy rate, implantation rate, live birth rate, miscarriages, perinatal outcomes, and birth weight were comparable.

CONCLUSION

We could not demonstrate that the post-thaw culture had a significant impact on the outcome of FET cycles.

Serum estradiol level on trigger day impacts clinical pregnancy rate in modified natural frozen embryo transfer cycles

OBJECTIVE

To examine the predictive value of serum estradiol and progesterone on the day of human chorionic gonadotropin (hCG) administration and embryo transfer for clinical pregnancy rate in modified natural-cycle frozen embryo transfer (NC-FET).

METHODS

In a longitudinal prospective study, all eligible women who underwent NC-FET cycles with hCG triggering in Royan Institute, Tehran, Iran, from June 1, 2015, to December 31, 2016, were evaluated. Serum estradiol and progesterone levels were measured at menstrual cycle initiation, on day of trigger with hCG, on day of embryo transfer, and in pregnant women every 7 days until the observation of a gestational sac with embryonic heartbeat.

RESULTS

In total, 101 modified natural FET cycles were assessed, and the clinical pregnancy and live birth rates achieved were 34 (33.6%) and 32 (31.6%), respectively. The changes in estradiol level during early pregnancy showed an increase by an average of 200 pg/mL per week. Multivariable logistic regression analysis showed that only the estradiol level on the hCG day was a significant predictive variable for clinical pregnancy following NC-FET (P=0.04).

CONCLUSION

Estradiol level on the day of hCG trigger predicted the clinical pregnancy rates after modified NC-FET; this likely mirrored the developmental competence of the corpus luteum and an appropriate luteal structure-function.

Mechanics of mouse blastocyst hatching revealed by a hydrogel-based microdeformation assay

Blastocyst hatching is crucial for implantation of mammalian embryos and a common failure point during in vitro fertilization (IVF). We have little knowledge of the mechanical basis whereby an embryo hatches out of the zona pellucida. We have developed a technique to measure blastocyst pressure, allowing us to quantify physiological parameters and providing additional measures of efficiency in IVF optimization. We find that mechanical stretching of the zona by the blastocyst is essential for efficient hatching. Cryopreservation and thawing of embryos is common during IVF. Our technique reveals significant differences in microphysiology between fresh and thawed embryos. Our experimental and associated mathematical techniques are also applicable to other biological systems involving cavity formation, providing an approach for measuring forces in diverse contexts.

Mammalian embryos are surrounded by an acellular shell, the zona pellucida. Hatching out of the zona is crucial for implantation and continued development of the embryo. Clinically, problems in hatching can contribute to failure in assisted reproductive intervention. Although hatching is fundamentally a mechanical process, due to limitations in methodology most studies focus on its biochemical properties. To understand the role of mechanical forces in hatching, we developed a hydrogel deformation-based method and analytical approach for measuring pressure in cyst-like tissues. Using this approach, we found that, in cultured blastocysts, pressure increased linearly, with intermittent falls. Inhibition of Na/K-ATPase led to a dosage-dependent reduction in blastocyst cavity pressure, consistent with its requirement for cavity formation. Reducing blastocyst pressure reduced the probability of hatching, highlighting the importance of mechanical forces in hatching. These measurements allowed us to infer details of microphysiology such as osmolarity, ion and water transport kinetics across the trophectoderm, and zona stiffness, allowing us to model the embryo as a thin-shell pressure vessel. We applied this technique to test whether cryopreservation, a process commonly used in assisted reproductive technology (ART), leads to alteration of the embryo and found that thawed embryos generated significantly lower pressure than fresh embryos, a previously unknown effect of cryopreservation. We show that reduced pressure is linked to delayed hatching. Our approach can be used to optimize in vitro fertilization (IVF) using precise measurement of embryo microphysiology. It is also applicable to other biological systems involving cavity formation, providing an approach for measuring forces in diverse contexts.

Murine embryos exposed to human endometrial MSCs-derived extracellular vesicles exhibit higher VEGF/PDGF AA release, increased blastomere count and hatching rates

Endometrial Mesenchymal Stromal Cells (endMSCs) are multipotent cells with immunomodulatory and pro-regenerative activity which is mainly mediated by a paracrine effect. The exosomes released by MSCs have become a promising therapeutic tool for the treatment of immune-mediated diseases. More specifically, extracellular vesicles derived from endMSCs (EV-endMSCs) have demonstrated a cardioprotective effect through the release of anti-apoptotic and pro-angiogenic factors. Here we hypothesize that EV-endMSCs may be used as a co-adjuvant to improve in vitro fertilization outcomes and embryo quality. Firstly, endMSCs and EV-endMSCs were isolated and phenotypically characterized for in vitro assays. Then, in vitro studies were performed on murine embryos co-cultured with EV-endMSCs at different concentrations. Our results firstly demonstrated a significant increase on the total blastomere count of expanded murine blastocysts. Moreover, EV-endMSCs triggered the release of pro-angiogenic molecules from embryos demonstrating an EV-endMSCs concentration-dependent increase of VEGF and PDGF-AA. The release of VEGF and PDGF-AA by the embryos may indicate that the beneficial effect of EV-endMSCs could be mediating not only an increase in the blastocyst’s total cell number, but also may promote endometrial angiogenesis, vascularization, differentiation and tissue remodeling. In summary, these results could be relevant for assisted reproduction being the first report describing the beneficial effect of human EV-endMSCs on embryo development.

Prognostic factors for patients undergoing vitrified-warmed human embryo transfer cycles: a retrospective cohort study

We examined the prognostic factors for pregnancy in 210 vitrified-warmed embryo transfer (ET) cycles in 121 patients. The univariate analysis showed that age, gravida, the number of cycles associated with infertility caused by endometriosis, the number of previous assisted reproductive technology (ART) treatment cycles, and the number of ICSI procedures were significantly lower in pregnant cycles compared with non-pregnant cycles. The percentages of ET using at least one intact embryo and of ET using at least one embryo that had developed further after warming were significantly higher in pregnant cycles compared with non-pregnant cycles. Multivariate logistic regression analysis showed that previous ART treatment cycles, ET with at least one intact embryo, and ET using at least one embryo that had developed further were independent prognostic factors for pregnancy in vitrified-warmed ET cycles. We conclude that fewer previous ART treatment cycles, ET using at least one intact embryo, and ET with embryos that have developed further after warming might be favourable prognostic factors for pregnancy in vitrified-warmed ET cycles.

Predictors of twin live birth following cryopreserved double embryo transfer on day 3

PURPOSE

To determine embryo and cycle-specific parameters associated with twin live birth in day 3 cryopreserved double embryo transfer (DET) cycles, and to propose a new prediction model for external validation.

METHODS

All cycles with autologous or donor cryopreserved DET of day 3 embryos from 2002 to 2011 at a single academic institution with a singleton or twin live birth were included (n = 207). Patient characteristics, post-thaw embryo morphology and freeze-thaw parameters were compared between patients with a single and twin live birth.

RESULTS

Demographic characteristics were similar, except that patients delivering twins were younger at age of cryopreserved embryo transfer (CET), fewer were parous and more were anovulatory. Duration of embryo storage, time in culture post-thaw, endometrial thickness and use of assisted hatching were comparable. Six predictors of twin delivery were identified: patient age <35 year at CET, intact survival of the lead embryo, resumption of mitosis, 7-8 viable cells in the non-lead embryo, transfer of a lead embryo with ≥7 cells and a sum of ≥14 viable cells in the two transferred embryos. Regression modeling predicted a step-wise increase in the probability of twins with addition of each predictor; with all six present, the risk of twins was predicted to be 53 % and with none present, the risk decreased to 6 %.

CONCLUSIONS

The six identified variables associated with twin live birth following day 3 cryopreserved DET have been applied to derive a prediction model for estimating the risk of twin delivery. External validation of the model is required prior to clinical application.

Comparison of amino acid metabolism in frozen-thawed and fresh early-stage human embryos

AIMS

To compare the amino acid differences of changes of frozen-thawed early-stage human embryos and fresh cultured early-stage human embryos.

MATERIAL AND METHODS

Discarded embryos and their in vitro culture medium of patients who underwent in vitro fertilization-embryo transfer (IVF-ET) at the Research Center for Reproductive Medicine, the Sixth Affiliated Hospital of Sun Yat-sen University, from September 2010 to April 2011 were collected. Amino acid levels were determined by high performance liquid chromatography.

RESULTS

The amino acid differences of changes in the culture medium of fresh embryos (661.50 μmol/L) were significantly higher than in the medium of post-thawed embryos (232.00 μmol/L) at 0.5 h (P < 0.001). At 1 and 2 h, no significant difference of change was found in all amino acids. Differences in the concentration of amino acids between post-thawed embryos and blank control medium were already present beginning at 1 h.

CONCLUSIONS

The level of amino acid metabolism of frozen-thawed early-stage human embryos has already recovered from the state of metabolic stagnation during cryopreservation at 1 h of incubation after thawing, and the amino acid metabolism level at that time approximates that in fresh embryos before freezing. This may be established as the optimal embryo transfer time in IVF-ET.

A comparative study on the impact of fresh variables on the success of frozen-thawed embryo transfer cycles using 2PN sibling embryos in women with/without polycystic ovary syndrome

AIMS

The aim of the present study was to identify the fresh variables that influence the frozen-thawed embryo transfer (FET) outcome using sibling two pronuclei (2PN) embryos in women with polycystic ovary syndrome (PCOS) and non-PCOS women.

MATERIAL & METHODS

Fifty-five FET cycles were performed using sibling embryos randomly cryopreserved at 2PN states and basal/cycle characteristics of fresh variables were compared between PCOS and non-PCOS groups according to the success in FET pregnancy: group A (pregnant PCOS); group B (not pregnant PCOS); group C (pregnant non-PCOS); group D (not pregnant non-PCOS).

RESULTS

In PCOS patients, higher progesterone level on human chorionic gonadotropin (hCG) day was observed in group A than in group B (0.9 ± 0.0 vs. 0.5 ± 0.3, p = 0.004). In non-PCOS patients who achieved a pregnancy in the fresh cycle, a subsequent FET cycle using sibling 2PN embryos conferred a thirteen times increased chance of achieving pregnancy (OR 13.0; 95% CI, 2.3-74.1). Embryo quality and endometrial maturation were comparable between A and B or C and D.

CONCLUSIONS

The success of the fresh embryo transfer (ET)was the most important predictor of pregnancy in FET cycles in the non-PCOS group. The relationship between serum progesterone on hCG day in the fresh cycle and the outcome of subsequent FET would benefit further evaluation in PCOS group.

A critical appraisal of cryopreservation (slow cooling versus vitrification) of human oocytes and embryos

BACKGROUND

Vitrification is now a commonly applied technique for cryopreservation in assisted reproductive technology (ART) replacing, in many cases, conventional slow cooling methodology. This review examines evidence relevant to comparison of the two approaches applied to human oocytes and embryos at different developmental stages.

METHODS

Critical review of the published literature using PubMed with particular emphasis on studies which include data on survival and implantation rates, data from fresh control groups and evaluation of the two approaches in a single setting.

RESULTS

Slow cooling is associated with lower survival rates and compromised development relative to vitrification when applied to metaphase II (MII) oocytes, although the vitrification results have predominantly been obtained using direct contact with liquid nitrogen and there is some evidence that optimal protocols for slow cooling of MII oocytes are yet to be established. There are no prospective randomized controlled trials (RCTs) which support the use of either technique with pronuclear oocytes although vitrification has become the method of choice. Optimal slow cooling, using modifications of traditional methodology, and vitrification can result in high survival rates of early embryos, which implant at the same rate as equivalent fresh counterparts. Many studies report high survival and implantation rates following vitrification of blastocysts. Although slow cooling of blastocysts has been reported to be inferior in some studies, others comparing the two approaches in the same clinical setting have demonstrated comparable results. The variation in the extent of embryo selection applied in studies can lead to apparent differences in clinical efficiency, which may not be significant if expressed on a 'per oocyte used' basis.

CONCLUSIONS

Available evidence suggests that vitrification is the current method of choice when cryopreserving MII oocytes. Early cleavage stage embryos can be cryopreserved with equal success using slow cooling and vitrification. Successful blastocyst cryopreservation may be more consistently achieved with vitrification but optimal slow cooling can produce similar results. There are key limitations associated with the available evidence base, including a paucity of RCTs, limited reporting of live birth outcomes and limited reporting of detail which would allow assessment of the impact of differences in female age. While vitrification has a clear role in ART, we support continued research to establish optimal slow cooling methods which may assist in alleviating concerns over safety issues, such as storage, transport and the use of very high cryoprotectant concentrations.

Correlation between embryological factors and pregnancy rate: development of an embryo score in a cryopreservation programme

PURPOSE

To establish which embryo parameters, in frozen thawed embryo transfers, have the highest prognosis value in the establishment of pregnancy. The relative importance of different embryo parameters is used to develop an embryo score.

METHODS

Retrospective analysis of the implantation rate in 356 frozen/thawed single embryo transfers. A logistic regression model is used to establish an embryo score.

RESULTS

A direct correlation is established between the implantation rate and fresh embryo development (number of blastomeres and their symmetry), survival rate after thawing and mitosis resumption after overnight culture.

CONCLUSIONS

An embryo score is developed to determine the implantation potential of frozen/thawed embryos.

Resumption of mitosis in frozen-thawed embryos is not related to the chromosomal constitution

OBJECTIVE

To study the relation between the resumption of mitosis after thaw and chromosomal constitution in frozen-thawed embryos. In addition, to evaluate the correlation among the three parameters of resumption of mitosis after thaw, postthaw blastomere loss, and multinucleation.

DESIGN

Frozen-thawed embryos were morphologically evaluated at thaw and after 24 hours of culture. Then, fluorescence in situ hybridization (FISH) analysis, including enumeration of 13 chromosomes, was performed by using a combination of peptide nucleic acid and DNA probes.

SETTING

In vitro fertilization laboratory.

PATIENT(S)

Forty IVF and/or intracytoplasmic sperm injection patients.

INTERVENTION(S)

Embryo thawing, morphological evaluation, and fluorescence in situ hybridization analysis for aneuploidy screening.

MAIN OUTCOME MEASURE(S)

Resumption of mitosis, blastomere loss, multinucleation, and chromosome enumeration.

RESULT(S)

No difference was observed in the chromosomal constitution of embryos with and without resumption of mitosis. Neither was the postthaw blastomere loss connected to the chromosomal constitution. The resumption of mitosis was not associated with postthaw loss of blastomeres or with multinuclearity.

CONCLUSION(S)

Resumption of mitosis and blastomere loss of frozen-thawed embryos is not related to chromosome aberrations in the embryo. Further, the resumption of mitosis is not correlated with multinucleation. However, the high incidence of multinucleated embryos after thawing indicates that the freezing and thawing procedure may affect this condition.

A comparison of post-thaw results between embryos arising from intracytoplasmic sperm injection using surgically retrieved or ejaculated spermatozoa

OBJECTIVE

To study the effect of freeze-thaw on embryos derived from intracytoplasmic sperm injection (ICSI) using surgically retrieved and ejaculated spermatozoa.

DESIGN

Retrospective study.

SETTING

Private IVF center.

PATIENT(S)

Three hundred eighty-three patients undergoing frozen-thawed ET cycles.

INTERVENTION(S)

Testicular sperm aspiration (TESA) or percutaneous epididymal sperm aspiration (PESA) were the sperm surgical retrieval methods used for ICSI. Embryos resulting from ICSI using surgically retrieved and ejaculated spermatozoa were frozen, thawed, and transferred.

MAIN OUTCOME MEASURE(S)

Post-thaw survival, implantation, and pregnancy rates.

RESULT(S)

No differences were found between the ejaculated sperm and TESA/PESA groups in terms of post-thaw survival rate (68.4% vs. 66.1%, respectively), pregnancy rate (20.1% vs. 16.1%), and implantation rate (10.6% vs. 12.7%). Similar results were found for those variables when comparing TESA and PESA groups.

CONCLUSION(S)

Cleavage embryos arising from ICSI cycles using testicular and epididymal spermatozoa can be frozen with survival, pregnancy, and implantation rates comparable to those obtained with ejaculated spermatozoa.

Objective evaluation of the viability of cryopreserved oocytes

Recent studies of fundamental cryobiology, empirical observations and more systematic clinical experiences have generated a renewed interest in oocyte cryopreservation. Poor survival rate has long been the limiting factor which has prevented widespread adoption of oocyte storage. Slow-cooling and vitrification protocols developed in the last few years have apparently solved this problem, ensuring high recovery of viable oocytes from liquid nitrogen storage. However, the definition of oocyte viability appears rather vague. In fact, post-storage survival as assessed on morphological criteria, indicated by the absence of overt cell degeneration, is not necessarily synonymous with viability. Despite its sensitivity to low temperatures, the meiotic spindle can be preserved after cryopreservation and its constitution after thawing can be monitored non-invasively through polarized light microscopy. Assessment of oocyte cryopreservation via clinical parameters is a daunting task. Most studies are small and difficult to interpret because of confounding factors, such as age, patient selection and quality and strategy of use of the cryopreserved material. Some progress has been made, however, as suggested by recent experiences in which the implantation efficiency of embryos produced from thawed oocytes approaches that reported using cryopreserved embryos directly.

Embryonic factors affecting outcome from single cryopreserved embryo transfer

Multiple pregnancy minimization by single embryo transfer is becoming more prevalent, but is less common in the case of cryopreserved embryos. This study defines embryonic characteristics in single cryopreserved embryo transfers associated with success rates equivalent to those achieved when transferring two cryopreserved embryos. In a retrospective analysis of 6916 cryopreserved day-2 embryo transfer procedures, transfer of two cryopreserved embryos resulted in higher clinical pregnancy rates when compared with transfer of a single thawed embryo but was also associated with elevated multiple pregnancy rates (26.7% in women under 36). Optimal outcome (implantation rate of 30.9%) from single cryopreserved embryo transfer (SCET) in women under 36 was associated with cryopreservation at the 4-cell stage, loss of fewer than two blastomeres and subsequent cleavage of at least two surviving blastomeres. In comparison, transfer of two cryopreserved embryos in women under 36 resulted in pregnancy and implantation rates of 25.5 and 16.1% respectively. Interestingly, in cryopreserved 4-cell stage embryos, loss of a single blastomere did not reduce implantation potential and cleavage of only a single post-thaw blastomere was not indicative of increased implantation potential. Establishment of these critical thresholds provides a rational basis for SCET.

Similar outcome for cryopreserved embryo transfer following GnRH-antagonist/GnRH-agonist, GnRH-antagonist/HCG or long protocol ovarian stimulation

The pregnancy rates after triggering of final oocyte maturation with gonadotrophin-releasing hormone (GnRH) agonist in GnRH-antagonist ovarian stimulation protocols are lower than those following triggering with human chorionic gonadotrophin (HCG). Furthermore, lower pregnancy rates following GnRH-antagonist protocols compared with long GnRH-agonist protocols have been reported. The differences might be due to an impact on oocyte number and quality or on the endometrium. If any stimulation protocol had a negative impact on oocyte quality, then further evidence of this effect would be observed following frozen-thawed embryo transfer originating from that stimulation cycle. The outcome of frozen-thawed embryo transfer was retrospectively analysed using the long protocol with triptorelin depot 3.75 mg (n = 215) or 0.1 mg/day (n = 83), or GnRH-antagonist protocol with either HCG (n = 69) or GnRH-agonist (n = 25) for final oocyte maturation. The outcomes measured were implantation rate, clinical pregnancy rate, ongoing pregnancy rate and embryo survival rate. All outcomes were similar in the four groups. It is concluded that the potential for frozen-thawed embryos to implant and develop following transfer is independent of the GnRH-analogue and the final oocyte maturation protocol used in the collection cycle. Lower IVF embryo transfer success using GnRH-antagonist/GnRH-agonist protocol does not appear to be related to an adverse effect on oocyte quality.

Impact of the assessment of early cleavage in a single embryo transfer policy

The policy of single embryo transfer (SET) adopted for women <36 years old since 1 July 2003, strongly calls for improvement of embryo selection. A total of 196 cycles in which SET was performed were randomly allocated to two groups. In the first group, early cleavage was assessed (ECA) 25 h after insemination. The embryo with the best score that cleaved early, if present, was selected for transfer. In the second group, early cleavage was not assessed (ECNA) and embryo selection was based solely on the embryo score. Ninety-eight cycles were allocated in the ECA and ECNA group respectively. Early cleavage occurred in 64% of cycles and 32.2% of embryos. Patient population and embryo morphology were similar between the two groups, and similar delivery rates were observed (27.6 versus 24.5% respectively in the ECA and ECNA groups). The assessment of early cleavage as additional parameter did not improve the delivery rate in the single embryo transfer policy.

Advances in oocyte cryopreservation technology will eventually blur the ethical and moral boundaries between compensated egg sharing and commercialized oocyte donation

Compensated egg sharing was originally conceived as a patient self-help co-operative scheme to avoid overt 'commodification' of donor oocytes and prevent doctors and medical institutions from acting as 'brokers' of donated human material. As such, egg sharing is an ethically justifiable and much-preferred alternative to commercialized oocyte donation. However, recent advances in oocyte cryopreservation technology are likely to blur the ethical and moral boundaries between compensated egg sharing and commercialized oocyte donation. The banking of cryopreserved oocytes would negate the requirement for donors and recipients in egg sharing to have co-ordinated and synchronized treatment cycles. Instead, fertility doctors and medical institutions can now offer subsidized fertility treatment upfront to any patient willing to donate a portion of her retrieved cohort of oocytes for banking and subsequent donation. Thus, more opportunity is now open for them to act as 'middle-man' to broker the transaction of oocytes between donor and recipient, which would inevitably result in overt 'commodification' of donated human material. Administrative and processing fees will de finitely be billed to prospective recipients, for banking and storage of the cryopreserved oocytes, which would mean that a direct profit can now be made from the transaction of oocytes between donor and recipient.

Contribution of embryo cryopreservation to elective single embryo transfer in IVF–ICSI

Single embryo transfer is the best way to reduce the risk of multiple pregnancy in IVF-intracytoplasmic sperm injection (ICSI). Between June 2002 and December 2004, all patients (first cycle, female age <38 years) were offered the choice between having one (SET) or two (DET) embryos transferred. Among 493 couples, 428 had at least two good quality embryos, and among them, 32% opted for SET. The SET and DET populations were not comparable (patients in the SET group were younger and had more oocytes retrieved), and therefore a paired, case-control analysis was performed involving 130 SET couples and 130 DET couples, matched according to the female partners' ages and the numbers of embryos available. All of the SET patients, and 82% of the DET group, had at least one embryo cryopreserved, (3.9 versus 2.8 embryos). The option of SET was continued for the frozen-thawed embryo transfers. The pregnancy rate following embryo transfer was significantly lower after SET compared with DET for both fresh (27.6 versus 36.9%; P < 0.05) and frozen-thawed (14.4 versus 23.5%) embryos. However, the cumulative live birth rates following the transfer of fresh and frozen embryos were identical between the two groups (43 versus 45%), with a high prevalence of twins following DET (34 versus 0%).