Incidence of chromosomal abnormalities from a morphologically normal cohort of embryos in poor-prognosis patients

Optimizing single blastocyst selection: the role of day 3 embryo morphology in vitrified-warmed blastocyst transfer cycles

RESEARCH QUESTION

Can day 3 embryo morphology serve as an independent criterion for optimal single blastocyst selection?

DESIGN

This retrospective, single-centre cohort study included 1517 single vitrified-warmed blastocyst transfer (SVBT) cycles conducted between October 2019 and July 2022. The live birth rate (LBR) and other clinical outcomes of SVBT cycles were evaluated, considering both good-quality and non-good-quality day 3 embryos. The associations of day 3 morphological characteristics, encompassing number of blastomeres and embryo grade, were assessed. Multivariable analyses were undertaken using multiple models adjusted for day of blastocyst development and blastocyst grade.

RESULTS

Blastocysts from good-quality day 3 embryos had significantly higher LBR compared with those from non-good-quality embryos for both day 5 (51.5% versus 42.9%; P = 0.013) and day 6 (25.1% versus 17.6%; P = 0.018) blastocysts. LBR did not differ significantly with number of blastomeres on day 3, regardless of day of blastocyst development (day 5/6) or blastocyst grade. LBR varied significantly by day 3 embryo grade for both day 5 (48.0%, 51.5%, 46.6% and 32.7% for grades I, II, III and IV-V; P = 0.005) and day 6 (41.5%, 23.6%, 15.9% and 16.1% for grades I, II, III and IV-V; P = 0.001) blastocysts. Multivariable logistic regression revealed that non-good-quality embryos and lower morphological grade (IV-V) on day 3 were significantly and negatively correlated with LBR, while the number of blastomeres on day 3 was not an independent factor.

CONCLUSIONS

When selecting blastocysts of equal quality for SVBT cycles, those with higher day 3 morphological scores are preferred. Day 3 morphological evaluation is a valuable supplement to conventional selection methods.

Should we should consider day 3 blastomere number during single vitrified-warmed blastocyst transfer cycle? A retrospective study

The present study investigated whether day 3 blastomere number has an effect on the clinical outcomes during single vitrified-warmed blastocyst transfer cycles. A total of 3294 vitrified-warmed single day 5 blastocyst transferred cycles were analyzed in this retrospective study from January 2018 to December 2021. The cycles were divided into ≥ 7 and < 7 blastomere groups depending on the day 3 embryo blastomere number. The clinical outcomes were compared between the two groups, moreover multivariate logistic regression analysis was conducted to investigate the correlation between the number of day 3 blastomeres and clinical outcomes. The chi-square test demonstrated that the rates of clinical pregnancy and live birth were significantly higher in the ≥ 7 blastomere group compared to the < 7 blastomere group with respect to single high-quality blastocyst transfer cycles. Conversely, these rates were similar in the two groups with respect to single low-quality blastocyst transfer cycles. These results were confirmed by multivariate logistic regression analysis. However, the miscarriage rate was higher in the < 7 blastomere group than in ≥ 7 group during low-quality blastocyst transfer cycles. These results suggested that day 3 blastomere number should be considered during single vitrified-warmed blastocyst transfer cycles. Thus, blastocsyts derived from ≥ 7 blastomere embryos are preferred when choosing the same quality blastocysts.

Effect of Day 3 cell number on the live birth rate of vitrified-warmed Day 5 single blastocyst transfer in young women

BACKGROUND

Previous studies have reported inconsistent results regarding blastocyst selection with a high day 3 (D3) cell number and the eventual pregnancy outcomes. Thus, in this study, the relationship between the D3 cell number and clinical outcomes of day 5 single blastocyst transfer (SBT) in vitrified-warmed transfer cycles was investigated.

METHODS

Our retrospective study included 1144 day 5 SBT in vitrified-warmed cycles between February 2016 and February 2021. All cycles were the first vitrified-warmed cycles, and the female patients were less than 35 years of age. Based on the D3 cell number, the cycles were divided into four groups, as follows: group A (3-7 cells, n = 130); group B (8-9 cells, n = 621); group C (10-12 cells, n = 328); and group D (13-16 cells, n = 65). The differences in the live birth rate (LBR), clinical pregnancy rate, and miscarriage rate were examined among the four groups.

RESULTS

The LBR and clinical pregnancy rate increased with the D3 cell number (P < 0.01). No significant difference was found in the miscarriage rate among the groups (P = 0.055). After adjusting for confounding factors, the LBR was significantly higher in groups C (odds ratio [OR] = 1.477, 95% confidence interval [CI]: 1.124-1.941, P = 0.005) and D (OR = 2.000, 95% CI: 1.166-3.429, P = 0.012) than in group B.

CONCLUSIONS

A high D3 cell number (> 9 cells) was associated with a high LBR in the vitrified-warmed day 5 SBT cycles of patients < 35 years of age. The cell number of D3 embryos can be an important reference indicator for blastocyst selection. Among blastocysts with the same morphological score, those with > 9 cells on D3 can be preferentially selected for transplantation.

Risk of embryo aneuploidy is affected by the increase in sperm DNA damage in recurrent implantation failure patients under ICSI-CGH array cycles

This study investigates the relationship between sperm DNA damage in recurrent implantation failure (RIF) patients treated with comparative genomic hybridisation array-intracytoplasmic sperm injection (CGH array-ICSI) cycles and embryo aneuploidy screening. Forty-two RIF couples were selected. Sperm DFI was measured using TUNEL by flow cytometry. Two groups were defined as follows: (i) sperm with high DFI (> 20%); and (ii) low DFI (< 20%). Semen parameters, total antioxidant capacity (TAC), and malondialdehyde formation (MDA) were also measured in both groups. Following oocyte retrieval and ICSI procedure, blastomere biopsy was performed at the 4th day of development and evaluated with CGH-array. The high DFI group had a significant (p = 0.04) increase in the number of aneuploid embryos compared to the low one. According to Poisson regression results, the risk of aneuploidy embryos in the high DFI group was 55% higher than the low DFI group (RR = 1.55; 95% CI = 1.358-1.772). Moreover, chromosomal analysis showed an elevation of aneuploidy in chromosomes number 16 and 20 in the high DFI group compared to the low DFI group (p < 0.05). The high DFI in RIF patients may significantly affect the risk of aneuploidy embryos. Therefore, embryo selection by CGH-array should be considered for couples with high levels of sperm DNA fragmentation.

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.

Rate of Post-Fertilization Mitotic Activity Predicts Embryonic Competence via Next Generation Sequencing: An Analysis of 39,301 Cleavage Stage Embryos

Objective

To investigate the association between cleavage stage development, embryonic competence, and euploidy in patients undergoing in vitro fertilization (IVF) with subsequent next generation sequencing.

Methods

The retrospective cohort study included patients at an academic fertility center who underwent IVF with at least one cleavage stage embryo from 2016 to 2019. Embryos were analyzed as slow (<6 cells), intermediate (6-8 cells), or fast (>8 cells); day 3 cell count was also analyzed as a continuous variable. Primary outcomes were blastulation rate, biopsied blastocyst rate, and euploid rate. Odds of blastulation, biopsy, and euploidy were also calculated. Additionally, we modeled the predicted probability of an embryo reaching blastulation, biopsy, and euploidy based on cleavage stage development.

Results

When compared with intermediate and slow cohorts, fast cleaving embryos had significantly higher rates of blastulation (82.70% vs. 75.13 vs. 42.48%), biopsy (55.04% vs. 44.00% vs. 14.98%), and euploidy (50.65% vs. 47.93% vs. 48.05%). After adjustment for covariates, there was a significant association between cleavage stage development and odds of blastulation (OR 1.38, 95% CI 1.29-1.48), biopsy (OR 1.42, 95% CI 1.34-1.51), and euploidy (OR 1.08, 95% CI 1.01-1.17). Finally, we observed significant associations between cleavage stage development and predicted probability of reaching blastulation (OR 1.29, 95% CI 1.27-1.32), biopsy (OR 1.24, 95% CI 1.22-1.26), and euploidy (OR 1.02, 95% CI 1.01-1.04).

Conclusions

Cleavage stage embryos with greater mitotic activity perform as well as or better than intermediate or slower cleaving embryos. Rapidly cleaving embryos have high rates of euploidy and significant clinical potential.

Prospects of Germline Nuclear Transfer in Women With Diminished Ovarian Reserve

Diminished ovarian reserve (DOR) is associated with a reduced quantity and quality of the retrieved oocytes, usually leading to poor reproductive outcomes which remain a great challenge for assisted reproduction technology (ART). Women with DOR often have to seek for oocyte donation, precluding genetically related offspring. Germline nuclear transfer (NT) is a novel technology in ART that involves the transfer of the nuclear genome from an affected oocyte/zygote of the patient to the cytoplast of an enucleated donor oocyte/zygote. Therefore, it offers opportunities for the generation of genetically related embryos. Currently, although NT is clinically applied only in women with serious mitochondrial DNA disorders, this technology has also been proposed to overcome certain forms of female infertility, such as advanced maternal age and embryo developmental arrest. In this review, we are proposing the NT technology as a future treatment option for DOR patients. Strikingly, the application of different NT strategies will result in an increase of the total number of available reconstituted embryos for DOR patients.

Towards the selection of embryos with the greatest implantation potential

Choosing the most suitable embryo remains challenging as the standard approach to select top-quality embryos for transfer rely on static morphological assessment. It is completed after fertilisation, on days 3 and 5 post oocyte retrieval and evaluates the size and number of blastomeres, presence of nucleation and percentage of fragmentation for cleavage stage embryos. Because of the limited number of observations during the morphological assessment, morphokinetic development of embryos has been implemented. It shows a broader image of embryo behaviour with precise evaluation of the timing of events. Yet, studies are inconsistent and debatable in predicting the parameters to identify chromosomal abnormalities. Pre-implantation genetic testing detects dysmorphic embryos and correlate their developmental potential to the assessed morphology. However, the clinical utility of PGT-aneuploidy remains controversial. The future relies on newly described scoring systems such as artificial intelligence and non-invasive PGT, yet their application and actual success rate still lacks supportive evidence.

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.

The hare and the tortoise: extreme mitotic rates and how these affect live birth

RESEARCH QUESTION

Is live birth of patients with excessive slow (no blastocyst on day 5) and fast mitotic rate (full blastocyst development on day 4) comparable to a matched control standard (blastocyst formation on day 5)?

DESIGN

In this retrospective matched (age and anti-Müllerian hormone [AMH]) case-control study rates of fertilization, blastulation, implantation, clinical pregnancy and live birth were compared in couples with male factor indication, prolonged embryo culture and fresh single morula and blastocyst transfer.

RESULTS

The rates of implantation, clinical pregnancy and live birth in the slow-developing group were significantly (P < 0.001) lower (17.6%, 13.7%, and 11.8%, respectively) compared with the fast (58.5%, 52.5%, 47.5%) and normal growing counterparts (51.5%, 42.6%, 39.6%). No differences in neonatal outcome could be observed between the three groups. Sex ratio in the fast-growing group was not different from the other cohorts.

CONCLUSIONS

Extremely slow development, as assessed by the absence of blastulation on day 5, is a negative predictor of pregnancy and live birth. In contrast, the fear that extremely fast-growing embryos may represent an aneuploid cohort of embryos is unsubstantiated. Day-4 full blastocysts can preferentially be considered for transfer.

In vitro production of horse embryos predisposes to micronucleus formation, whereas time to blastocyst formation affects likelihood of pregnancy

Invitro embryo production is an increasingly popular means of breeding horses. However, success is limited by a high incidence of early embryo loss. Although there are various possible causes of pregnancy failure, chromosomal abnormalities, including aneuploidy, are important potential contributors. This study evaluated the frequency of micronucleus formation as a proxy for aneuploidy in invitro-produced (IVP) and invivo-derived horse blastocysts. Associations between IVP embryo morphology, frequency of nuclear abnormalities and the likelihood of pregnancy were investigated. IVP blastocysts exhibited a higher frequency of cells with micronuclei than invivo-derived embryos (10% vs 1% respectively; P=0.05). This indication of chromosomal instability may explain the higher incidence of pregnancy failure after transfer of IVP embryos. However, the frequency of micronuclei was not correlated with brightfield microscopic morphological characteristics. Nevertheless, IVP embryos reaching the blastocyst stage after Day 9 of invitro culture were less likely to yield a pregnancy than embryos that developed to blastocysts before Day 9 (27% vs 69%), and embryos that had expanded before transfer were more likely to undergo embryonic death than those that had not expanded (44% vs 10%). These findings indicate that current embryo culture conditions are suboptimal and that the speed of embryo development is correlated with pregnancy survival.

Use of time-lapse imaging to evaluate morphokinetics of in vitro equine blastocyst development after oocyte holding for two days at 15°C versus room temperature before intracytoplasmic sperm injection

Time-lapse imaging was used to establish the morphokinetics of equine embryo development to the blastocyst stage after invitro oocyte maturation (IVM), intracytoplasmic sperm injection (ICSI) and embryo culture, in oocytes held overnight at room temperature (22-27°C; standard conditions) before IVM. Embryos that developed to the blastocyst stage underwent precleavage cytoplasmic extrusion and cleavage to the 2-, 3- and 4-cell stages significantly earlier than did embryos that arrested in development. We then determined the rate of blastocyst formation after ICSI in oocytes held for 2 days at either 15°C or room temperature before IVM (15-2d and RT-2d treatment groups respectively). The blastocyst development rate was significantly higher in the 15-2d than in the RT-2d group (13% vs 0% respectively). The failure of blastocyst development in the RT-2d group precluded comparison of morphokinetics of blastocyst development between treatments. In any condition examined, development to the blastocyst stage was characterised by earlier cytoplasmic extrusion before cleavage, earlier cleavage to 2- and 4-cell stages and reduced duration at the 2-cell stage compared with non-competent embryos. In conclusion, this study presents morphokinetic parameters predictive of embryo development invitro to the blastocyst stage after ICSI in the horse. We conclude that time-lapse imaging allows increased precision for evaluating effects of different treatments on equine embryo development.

The Feasibility of All-Blastocyst-Culture and Single Blastocyst Transfer Strategy in Elderly Women: A Retrospective Analysis

Objective

To investigate the feasibility and clinical outcome of the all-blastocyst-culture and single blastocyst transfer strategy in women aged ≥35 years.

Methods

A retrospective analysis of patients aged ≥35 years undergoing IVF/ICSI was performed from January 2017 to April 2019 in the reproductive center of the Second Affiliated Hospital of Wenzhou Medical University. A total of 155 cases treated with ovarian hyperstimulation by prolonged protocol and implemented single (84 cases) or double (71 cases) blastocyst transfer were collected. Then, patients were further divided into <38 yr. group and ≥38 yr. group, and the laboratory and clinical outcomes were compared between the groups.

Results

The double-blastocyst-transfer (DBT) group showed higher clinical pregnancy rate and multiple pregnancy rate and lower neonatal birth weight than those in the single-blastocyst-transfer (SBT) group (P < 0.05). However, there were no statistically significant differences between the groups in the embryo implantation rate, biochemical pregnancy rate, miscarriage rate, preterm delivery rate, and term birth rate. For patients < 38 yr., SBT significantly reduced the multiple pregnancy rate and increased the neonate birth weight without significant reduction in the clinical pregnancy rate. While in the ≥38 yr. group, there are no differences in pregnancy outcomes between SBT and DBT. Logistic regression analysis showed that the number of MII oocytes was positively correlated with the live birth rate (OR = 1.18) and negatively correlated with the miscarriage rate (OR = 0.844), suggesting that elderly patients with relatively normal ovarian reserve would obtain better prospect in pregnancy. The number of fetal heart beat in pregnancy was negatively correlated with the live birth rate (OR = 0.322) and positively correlated with the preterm birth rate (OR = 7.16).

Conclusion

The strategy of all-blastocyst-culture and single blastocyst transfer is feasible, safe, and effective for elderly patients with normal ovarian reserve, which would reduce the multiple pregnancy rate.

Blastocyst-stage embryos provide better frozen-thawed embryo transfer outcomes for young patients with previous fresh embryo transfer failure

Older patients or patients with a reduced ovarian response have a low number of embryos, which limits the opportunity for embryo selection. However, for young patients undergoing frozen-thawed embryo transfer (ET), it remains unclear whether embryo stage affects pregnancy outcomes. In the present study, a total of 2952 patients undergoing their first frozen-thawed ET were divided into two groups: patients who had experienced one failed fresh ET (Group A) and patients who had not received fresh ET because of the high risk of ovarian hyperstimulation syndrome (OHSS) (Group B). Our results show that Group B patients had a significantly higher clinical pregnancy rate (CPR) and live birth rate (LBR) than Group A patients. However, Group A patients who underwent blastocyst-stage frozen-thawed ET had a significantly higher CPR and LBR and a lower ectopic pregnancy rate (ePR) than did those who underwent cleavage-stage frozen-thawed ET. In Group B, CPR, ePR, LBR and spontaneous abortion rate (sAR) were similar with blastocyst-stage and cleavage-stage frozen-thawed ET. These results suggest that blastocyst-stage frozen-thawed ET is more appropriate for young patients who had previously undergone one failed fresh ET cycle.

Embryos derived from donor or patient oocytes are not different for in vitro fertilization outcomes when PGT allows euploid embryo selection: a retrospective study

BACKGROUND

At our facilities, patients that received embryos using donor oocyte during in vitro fertilization (IVF), usually have had at least one failed attempt to produce at least one euploid embryo with their own oocytes; however, the current debate between using donor over patient oocytes remains inconclusive. We examined the aneuploidy rate and IVF clinical outcomes from embryos derived from either donor or patient oocytes.

METHODS

Retrospectively, 973 cycles were examined of patients who underwent a standard IVF protocol. Chromosomal content was determined using Pre-implantation Genetic Testing (PGT) by either microarray-comparative genomic hybridization or Next-generation sequencing from either Day 3 (blastocysts) or Day 5 (trophectoderm) embryo biopsies, respectively. Embryo implantation was confirmed by serum β-hCG (> 10 m IU/mL/Day 14), whereas clinical pregnancy by a fetal heartbeat (Week 6.5-8).

RESULTS

Embryos derived from donor oocytes presented with more monosomies than embryos derived from patient oocytes (41.2% vs. 25.4%, p < 0.05, respectively); however, only Trisomy 7 (0.4% vs. 2.3%, p < 0.05) and Trisomy in X (0.7% vs. 2.3%, p < 0.05) were significantly less present when compared to patient oocyte derived embryos. Interestingly, rates for embryo implantation (46.7% vs. 50.8%, p = 0.35), clinical pregnancy (38.5% vs. 43.1%, p = 0.30), and live birth (30.5% vs. 30.5%, p = 0.99) were similar for embryos derived from donor and patient oocytes. These results did not change when adjusted for the number of embryos implanted.

CONCLUSION

Here, we show no significant differences in achieving pregnancy when using donor oocytes. Taking into consideration that aneuploidy rates are > 30% in embryos, independent of the oocyte origin, PGT should be recommended with donor oocytes as well.

Should all embryos be cultured to blastocyst for advanced maternal age women with low ovarian reserve: a single center retrospective study

The purpose of this study is to determine whether all-blastocyst-culture can benefit advanced maternal age (AMA) patients with low ovarian reserve. We retrospectively analyze AMA patients with low ovarian reserve undergoing IVF/ICSI in Reproductive Medicine Research Center of the Sixth Affiliated Hospital of Sun Yat-sen University from May 2016 to August 2017. We divide them into group A (all-blastocyst-culture) and group B (none-blastocystculture) based on different culture approach of D3 transferrable embryo. We compared the cumulative biochemical pregnancy rate and cumulative clinical pregnancy rate between them. A total of 261 eligible patients are included, with 151 in group A and 110 in group B. The basic conditions of the two groups show no difference. Cumulative biochemical pregnancy rate/clinical pregnancy rate in group A is higher than that of group B, though not statistically significant (p > .05). After removing patients canceling embryo transfer due to failure in blastocyst culture, the cumulative biochemical pregnancy rate/clinical pregnancy rate in group A is significantly higher than group B (p < .05). Multivariate analysis showed that female age and the number of D3 transferrable embryo are risk factors for the failure of blastocyst culture (OR = 0.672 and 2.270, 95%CI 0.511-0.883 and 1.203-4.284, p = .004 and p = .011, respectively). Hence, we drew to conclusion that all-blastocyst-culture will not adversely affect the pregnancy outcome of AMA patients with low ovarian reserve.

Type of chromosome abnormality affects embryo morphology dynamics

OBJECTIVE

To study the differences in the cleavage time between types of embryo chromosomal abnormalities and elaborate algorithm to exclude aneuploid embryos according to the likelihood to be euploid.

DESIGN

Retrospective cohort study.

SETTING

University affiliated private center.

PATIENT(S)

Preimplantational genetic screening patients (n = 112) including cases of advanced maternal age, repeated implantation failure, and recurrent miscarriage. A total of 485 embryos were analyzed.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

All biopsied embryos were cultured in an incubator with time-lapse technology, cleavage timing from insemination to day 3 and all kinetic parameters that have been described in previous studies by our group.

RESULT(S)

Logistic regression analysis were used to identify morphokinetic parameters and some were strongly associated with complex aneuploid embryos; t3 (odds ratio = 0.590, 95% confidence interval 0.359-0.971) and t5-t2 (odds ratio = 0.151, 95% confidence interval 0.082-0.278).

CONCLUSION(S)

Embryo morphokinetics are affected by chromosome aneuploidy and further analysis of the chromosome content reveals higher differences when the complexity in the chromosome disorders is increased. The use of time-lapse monitoring, although not able to detect an abnormal embryo, may be potentially useful to discard those embryos with high risk of complex chromosomal abnormalities.

Cleavage stage versus blastocyst stage embryo transfer in assisted reproductive technology

BACKGROUND

Advances in cell culture media have led to a shift in in vitro fertilisation (IVF) practice from cleavage stage embryo transfer to blastocyst stage transfer. The rationale for blastocyst 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 transfers improve the live birth rate, and other associated outcomes, compared with cleavage stage (day 2 to 3) embryo transfers.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library; 2016, Issue 4), MEDLINE, EMBASE, PsycINFO, CINAHL, and Bio extracts from inception to 4th April 2016. 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 blastocyst versus cleavage stage transfers.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Our primary outcomes were live birth and cumulative clinical pregnancy rates. Secondary outcomes were clinical pregnancy, multiple pregnancy, high order pregnancy, miscarriage, failure to transfer embryos, and embryo freezing. We assessed the overall quality of the evidence for the main comparisons using GRADE methods.

MAIN RESULTS

We included 27 RCTs (4031 couples or women).The live birth rate following fresh transfer was higher in the blastocyst transfer group (odds ratio (OR) 1.48, 95% confidence interval (CI) 1.20 to 1.82; 13 RCTs, 1630 women, I(2) = 45%, low quality evidence) following fresh transfer. This suggests that if 29% of women achieve live birth after fresh cleavage stage transfer, between 32% and 42% would do so after fresh blastocyst stage transfer.There was no evidence of a difference between the groups in rates per couple of cumulative pregnancy following fresh and frozen-thawed transfer after one oocyte retrieval (OR 0.89, 95% CI 0.64 to 1.22; 5 RCTs, 632 women, I(2) = 71%, very low quality evidence).The clinical pregnancy rate was also higher in the blastocyst transfer group, following fresh transfer (OR 1.30, 95% CI 1.14 to 1.47; 27 RCTs, 4031 women, I(2) = 56%, moderate quality evidence). This suggests that if 36% of women achieve clinical pregnancy after fresh cleavage stage transfer, between 39% and 46% would do so after fresh blastocyst stage transfer.There was no evidence of a difference between the groups in rates of multiple pregnancy (OR 1.05, 95% CI 0.83 to 1.33; 19 RCTs, 3019 women, I(2) = 30%, low quality evidence), or miscarriage (OR 1.15, 95% CI 0.88 to 1.50; 18 RCTs, 2917 women, I(2) = 0%, low quality evidence). These data are incomplete as under 70% of studies reported these outcomes.Embryo freezing rates were lower in the blastocyst transfer group (OR 0.48, 95% CI 0.40 to 0.57; 14 RCTs, 2292 women, I(2) = 84%, 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; 17 RCTs, 2577 women, I(2) = 36%, moderate quality evidence). This suggests that if 1% of women have no embryos transferred in (planned) fresh cleavage stage transfer, between 2% and 4% will have no embryos transferred in (planned) fresh blastocyst stage transfer.The evidence was of low quality for most outcomes. The main limitation was serious risk of bias, associated with failure to describe acceptable methods of randomisation, and unclear or high risk of attrition bias.

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 than fresh cleavage stage transfer. There was no evidence of a difference between the groups in cumulative pregnancy rates derived from fresh and frozen-thawed cycles following a single oocyte retrieval, but the evidence for this outcome was very low quality. Thus, although there is a benefit favouring blastocyst transfer in fresh cycles, it remains unclear whether the day of transfer impacts on cumulative live birth and pregnancy rates. Future RCTs should report rates of live birth, cumulative live birth, and miscarriage to enable couples or women undergoing assisted reproductive technology (ART) and service providers to make well informed decisions on the best treatment option available.

The Relationship between Cell Number, Division Behavior and Developmental Potential of Cleavage Stage Human Embryos: A Time-Lapse Study

Day 3 cleavage embryo transfer is routine in many assisted reproductive technology centers today. Embryos are usually selected according to cell number, cell symmetry and fragmentation for transfer. Many studies have showed the relationship between cell number and embryo developmental potential. However, there is limited understanding of embryo division behavior and their association with embryo cell number and developmental potential. A retrospective and observational study was conducted to investigate how different division behaviors affect cell number and developmental potential of day 3 embryos by time-lapse imaging. Based on cell number at day 3, the embryos (from 104 IVF/intracytoplasmic sperm injection (ICSI) treatment cycles, n = 799) were classified as follows: less than 5 cells (< 5C; n = 111); 5–6 cells (5–6C; n = 97); 7–8 cells (7–8C; n = 442), 9–10 cells (9–10C; n = 107) and more than 10 cells (>10C; n = 42). Division behavior, morphokinetic parameters and blastocyst formation rate were analyzed in 5 groups of day 3 embryos with different cell numbers. In <5C and 5–6C embryos, fragmentation (FR; 62.2% and 30.9%, respectively) was the main cause for low cell number. The majority of 7–8C embryos exhibited obvious normal behaviors (NB; 85.7%) during development. However, the incidence of DC in 9–10C and >10C embryos increased compared to 7–8C embryos (45.8%, 33.3% vs. 11.1%, respectively). In ≥5C embryos, FR and DC significantly reduced developmental potential, whereas <5C embryos showed little potential irrespective of division behaviors. In NB embryos, the blastocyst formation rate increased with cell number from 7.4% (<5C) to 89.3% (>10C). In NB embryos, the cell cycle elongation or shortening was the main cause for abnormally low or high cell number, respectively. After excluding embryos with abnormal division behaviors, the developmental potential, implantation rate and live birth rate of day 3 embryos increased with cell number.

High Aneuploidy Rates Observed in Embryos Derived from Donated Oocytes are Related to Male Aging and High Percentages of Sperm DNA Fragmentation

CAPSULE

Male aging effects on aneuploidy rates in embryos.

OBJECTIVE

Paternal age is associated with decreasing sperm quality; however, it is unknown if it influences chromosomal abnormalities in embryos. The objective of this study is to evaluate if the aneuploidy rates in embryos are affected by advanced paternal age.

METHODS

A total of 286 embryos, obtained from 32 in vitro fertilization/intracytoplasmic sperm injection cycles with donated oocytes in conjunction with preimplantation genetic diagnosis, were allocated according to paternal age in three groups: Group A: ≤39 years (n = 44 embryos); Group B: 40-49 years (n = 154 embryos); and Group C: ≥50 years (n = 88 embryos). Fertilization rates, embryo quality at day 3, blastocyst development, and aneuploidy embryo rates were then compared.

RESULTS

There was no difference in the seminal parameters (volume, concentration, and motility) in the studied groups. Fertilization rate, percentages of zygotes underwent cleavage, and good quality embryos on day 3 were similar between the three evaluated groups. The group of men ≥50 years had significantly more sperm with damaged DNA, low blastocyst development rate, and higher aneuploidy rates in embryos compared to the other two evaluated groups (P < 0.05).

CONCLUSIONS

Our findings suggest that advanced paternal age increases the aneuploidy rates in embryos from donated oocytes, which suggests that genetic screening is necessary in those egg donor cycles with sperm from patients >50 years old.

The Influence of Single Nucleotide Polymorphism Microarray-Based Molecular Karyotype on Preimplantation Embryonic Development Potential

In order to investigate the influence of the molecular karyotype based on single nucleotide polymorphism (SNP) microarray on embryonic development potential in preimplantation genetic diagnosis (PGD), we retrospectively analyzed the clinical data generated by PGD using embryos retrieved from parents with chromosome rearrangements in our center. In total, 929 embryos from 119 couples had exact diagnosis and development status. The blastocyst formation rate of balanced molecular karyotype embryos was 56.6% (276/488), which was significantly higher than that of genetic imbalanced embryos 24.5% (108/441) (P<0.001). No significant difference was detected in blastocyst formation rates in the groups of maternal age <30, 30-35 and >35 respectively. Blastocyst formation rates of male and female embryos were 44.5% (183/411) and 38.8% (201/518) respectively, with no significant difference between them (P>0.05). The rates of balanced molecular karyotype embryos vary from groups of embryos with different cell numbers at 68 hours after insemination. The blastocyst formation rate of embryos with 6-8 cells (48.1%) was significantly higher than that of embryos with <6 cells (23.9%) and with >8 cells (42.9%) (P<0.05). As for the unbalanced embryos, there was no significant difference of the distribution of abnormal molecular karyotypes in the subgroup of the arrest, morula and blastocyst. Thus, we conclude that embryos with balanced molecular karyotype have significant higher development potential than those with imbalanced molecular karyotype whilst maternal age, embryo gender and types of abnormal molecular karyotype have no significant influence on blastocyst formation. Compared with embryos with <6 and >8 cells, embryos with 6-8 blastomeres have higher rate of balanced molecular karyotype and blastocyst formation.

Why we should not select the faster embryo: lessons from mice and cattle

Many studies have shown that in vitro culture can negatively impact preimplantation development. This necessitates some selection criteria for identifying the best-suited embryos for transfer. That said, embryo selection after in vitro culture remains a subjective process in most mammalian species, including cows, mice and humans. General consensus in the field is that embryos that develop in a timely manner have the highest developmental competence and viability after transfer. Herein lies the key question: what is a timely manner? With emerging data in bovine and mouse supporting increased developmental competency in embryos with moderate rates of development, it is time to question whether the fastest developing embryos are the best embryos for transfer in the human clinic. This is especially relevant to epigenetic gene regulation, including genomic imprinting, where faster developing embryos exhibit loss of imprinted methylation, as well as to sex selection bias, where faster developmental rates of male embryos may lead to biased embryo transfer and, in turn, biased sex ratios. In this review, we explore evidence surrounding the question of developmental timing as it relates to bovine embryo quality, mouse embryo quality and genomic imprint maintenance, and embryo sex.

Increased blastomere number in cleavage-stage embryos is associated with higher aneuploidy

OBJECTIVE

To evaluate the relationship between blastomere number and aneuploidy.

DESIGN

Historical cohort study.

SETTING

In vitro fertilization clinic.

PATIENT(S)

Two hundred fifty-nine patients undergoing in vitro fertilization (IVF) in combination with comprehensive chromosomal screening of embryos.

INTERVENTION(S)

A total of 1,915 embryos were biopsied on day 3 and underwent comprehensive chromosomal screening with microarray-based comparative genomic hybridization.

MAIN OUTCOME MEASURE(S)

Relationship between day 3 blastomere number, aneuploidy rate, and progression to the blastocyst stage.

RESULT(S)

A number of day 3 blastomeres >9 was associated with significantly increased aneuploidy rates. Rapidly developing embryos were significantly more likely to blastulate regardless of their chromosomal status. Number of embryos per patient greater than 13 was independently associated with lower aneuploidy rates after controlling for maternal age. This trend was not significant with the use of a more clinically relevant threshold of greater than six embryos per patient.

CONCLUSION(S)

Embryos with 6-9 cells at the cleavage stage should be considered for transfer over embryos with >9 cells. Day 3 blastomere number may be used in conjunction with extended culture to improve selection of euploid embryos, especially when supernumerary embryos are available. Further studies are needed to show if these selection criteria improve clinical outcomes.

Are ART outcomes more successful in younger women? A retrospective study

It is well known that with increasing age, fertility potential decreases in women. Since some of the women who undergo assisted reproductive technology (ART) treatments are very young patients or young donors, fecundity investigation seems necessary in this group. Data from patients who underwent in vitro fertilisation/intra-cytoplasmic sperm injection (IVF/ICSI) over 20 years were analysed retrospectively. The records of 407 infertile patients aged 17-25 years (study group) and 407 infertile patients aged 26-35 years (control group) were collected. The number of follicles > 14 mm, retrieved oocytes, MII oocytes, cleaved embryos in both IVF and ICSI cycles were significantly higher in the study group when compared with the control group (p˂0.001). However, the rates of chemical pregnancies were similar between the two groups. It therefore seems unlikely that younger age has a positive effect in predicting infertility treatment outcomes.

Embryo culture and selection: morphological criteria

In this chapter, we have outlined the various morphological criteria for selection of the best embryo at each important milestone encountered in the progress from the oocyte to the blastocyst. As Gerris et al. stated, a combination of one, two, or even three selection points should lead to a more accurate selection of the best embryo, as no one criterion is better than the other. An embryo that fails to meet the entire set of selection criteria must be avoided as culture cannot correct an impaired embryo.

Cleavage stage versus blastocyst stage embryo transfer in assisted reproductive technology

BACKGROUND

Advances in cell culture media have led to a shift in in vitro fertilization (IVF) practice from early cleavage embryo transfer to blastocyst stage transfer. The rationale for blastocyst culture is to improve both uterine and embryonic synchronicity and enable self selection of viable embryos thus resulting in higher implantation rates.

OBJECTIVES

To determine if blastocyst stage (Day 5 to 6) embryo transfers (ETs) improve live birth rate and other associated outcomes compared with cleavage stage (Day 2 to 3) ETs.

SEARCH METHODS

Cochrane Menstrual Disorders and Subfertility Group Specialised Register of controlled trials, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE and Bio extracts. The last search date was 21 February 2012.

SELECTION CRITERIA

Trials were included if they were randomised and compared the effectiveness of early cleavage versus blastocyst stage transfers.

DATA COLLECTION AND ANALYSIS

Of the 50 trials that were identified, 23 randomised controlled trials (RCTs) met the inclusion criteria and were reviewed (five new studies were added in this update). The primary outcome was rate of live birth. Secondary outcomes were rates per couple of clinical pregnancy, cumulative clinical pregnancy, multiple pregnancy, high order pregnancy, miscarriage, failure to transfer embryos and cryopreservation. Quality assessment, data extraction and meta-analysis were performed following Cochrane guidelines.

MAIN RESULTS

Twelve RCTs reported live birth rates and there was evidence of a significant difference in live birth rate per couple favouring blastocyst culture (1510 women, Peto OR 1.40, 95% CI 1.13 to 1.74) (Day 2 to 3: 31%; Day 5 to 6: 38.8%, I(2) = 40%). This means that for a typical rate of 31% in clinics that use early cleavage stage cycles, the rate of live births would increase to 32% to 42% if clinics used blastocyst transfer.There was no difference in clinical pregnancy rate between early cleavage and blastocyst transfer in the 23 RCTs (Peto OR 1.14, 95% CI 0.99 to 1.32) (Day 2 to 3: 38.6%; Day 5 to 6: 41.6%) and no difference in miscarriage rate (13 RCTs, Peto OR 1.18, 95% CI 0.86 to 1.60). The four RCTs that reported cumulative pregnancy rates (266 women, Peto OR 1.58, 95% CI 1.11 to 2.25) (Day 2 to 3: 56.8%; Day 5 to 6: 46.3%) significantly favoured early cleavage. Embryo freezing rates (11 RCTs, 1729 women, Peto OR 2.88, 95% CI 2.35 to 3.51) and failure to transfer embryos (16 RCTs, 2459 women, OR 0.35, 95% CI 0.24 to 0.51) (Day 2 to 3: 3.4%; Day 5 to 6: 8.9%) favoured cleavage stage transfer.

AUTHORS' CONCLUSIONS

This review provides evidence that there is a small significant difference in live birth rates in favour of blastocyst transfer (Day 5 to 6) compared to cleavage stage transfer (Day 2 to 3). However, cumulative clinical pregnancy rates from cleavage stage (derived from fresh and thaw cycles) resulted in higher clinical pregnancy rates than from blastocyst cycles. The most likely explanation for this is the higher rates of frozen embryos and lower failure to transfer rates per couple obtained from cleavage stage protocols. Future RCTs should report miscarriage, live birth and cumulative live birth rates to enable ART consumers and service providers to make well informed decisions on the best treatment option available.

Expression profiles of cohesins, shugoshins and spindle assembly checkpoint genes in rhesus macaque oocytes predict their susceptibility for aneuploidy during embryonic development

High frequencies of chromosomal anomalies are reported in human and non-human primate in vitro-produced preimplantation embryos. It is unclear why certain embryos develop aneuploidies while others remain euploid. A differential susceptibility to aneuploidy is most likely a consequence of events that occur before oocyte collection. One hypothesis is that the relative transcript levels of cohesins, shugoshins and spindle assembly checkpoint genes are correlated with the occurrence of chromosomal anomalies. Transcript levels of these genes were quantified in individual oocytes that were either mature (group 1, low aneuploidy rate) or immature (group 2, high aneuploidy rate) at retrieval, utilizing TaqMan-based real-time PCR. The transcript level in each oocyte was categorized as absent, below the median or above the median in order to conduct comparisons. Statistically significant differences were observed between group 1 and group 2 for SGOL1 and BUB1. There were more oocytes with SGOL1 expression levels above the median in group 1, while oocytes lacking BUB1 were only observed in group 1. These findings suggest that higher SGOL1 levels in group 1 oocytes could better protect against a premature separation of sister chromatids than in embryos derived from group 2 oocytes. The absence of BUB1 transcripts in group 1 was frequently associated with reduced expression of either mitotic cohesins or shugoshins. We hypothesize that ablation of BUB1 could induce mitotic arrest in oocytes that fail to express a complete complement of cohesins and shugoshins, thereby reducing the number of developing aneuploid preimplantation embryos.

Down-regulation of HLA-G Attenuates Cleavage Rate in Human Triploid Embryos

INTRODUCTION

HLA-G is a major histocompatibility complex (MHC), class Ib molecule that is selectively expressed at the fetal-maternal interface. It is thought to play a role in protecting the fetus from the maternal immune response. Interestingly, the preimplantation embryo development (Ped) gene product Qa-2 is also a mouse MHC class Ib protein that affects cleavage and division of preimplantation mouse embryos and subsequent embryonic survival. Data from many human in vitro fertilization (IVF) clinics suggest that the mouse Ped phenomenon also exists in human because embryos fertilized at the same time have different cleavage rates and consequently different IVF outcomes. As HLA-G is expressed in human early embryos, it is highly regarded as the functional homologue of Qa-2. Whether HLA-G expression is correlated with the cleavage rate of human embryos has great potential clinical value.

METHODS

In this study, 45 human early abnormal fertilized embryos (3 PN) from patients undergoing in vitro fertilization were used to test the effects of HLA-G knock-down via infection with adenovirus carrying its specific siRNA on the cleavage rate in a 2-day culture period. One-way ANOVA, Post hoc and Chi-square were used to compare groups. A p-value smaller than 0.05 was considered statistically significant.

RESULTS

Knocking-down HLA-G in human pre-implantation stage embryos resulted in a higher cell arrest rate and a slower cleavage rate.

CONCLUSION

The results from the present study suggested that HLA-G might play an important role in early human embryo development.

Are poor responders patients at higher risk for producing aneuploid embryos in vitro?

PURPOSE

To test the hypothesis that aged women with poor ovarian response express an increase on embryo chromosomal alterations when compared to aged women who presented normal response.

METHODS

Couples undergoing intracytoplasmic sperm injection cycles with preimplantation genetic screening, were subdivided into two groups: Poor Responder group (n = 34), patients who produced ≤4 oocytes; and Normoresponder group (n = 50), patients who produced ≥5 oocytes. Groups were compared regarding cycles' outcomes and aneuploidy frequency.

RESULTS

There were no significant differences between and groups regarding the fertilization rate (p = 0.6861), clinical pregnancy (p = 0.9208), implantation (p = 0.6863), miscarriage (p = 0.6788) and the percentage of aneuploid embryos (p = 0.270). Embryo transfer rate was significantly lower on poor responder group (p = 0.0128) and logistic regression confirmed the influence of poor response on the chance of embryo transfer (p = 0.016).

CONCLUSIONS

Aged females responding poorly to gonadotrophins are not at a higher risk for producing aneuploid embryos in vitro.

The utility of embryo banking in order to increase the number of embryos available for preimplantation genetic screening in advanced maternal age patients

PURPOSE

to determine if embryo banking with PGS is more optimal than proceeding with PGS regardless of embryo number.

METHODS

patients were divided into 2 groups, group 1 were those that banked embryos and proceeded through another round of IVF prior to PGS, and group 2 underwent PGS regardless of embryo number. Group 2 was divided into group 2A (patients with >10 embryos) and group 2B (patients who had <10 embryos).

RESULTS

there was no difference in embryos biopsied, normal embryos, number transferred, and pregnancy rate between group 1 and 2. A significant number of patients did not have a transfer in group 2B (6/11) compared to group 1 (3/19) (P = 0.0419). There was no significance between pregnancy rates per transfer between group 1 (6/16) and group 2B (2/5).

CONCLUSION

our data suggests that banking will increase the odds of going to transfer but there was no increase in pregnancy rates.

Blastocyst embryo transfer is the primary determinant for improved outcomes in oocyte donation cycles

AIM

Using oocyte donation cycles as an ideal model, we sought to compare pregnancy and implantation rates in cleavage stage (day 3) versus blastocyst stage (day 6) embryo transfers (ET); assess the predictive value of blastocyst formation rates based on cleavage cell stage and morphology grade; and evaluate the ability to predict formation of high quality (HQ) blastocysts.

METHODS

Ninety three consecutive oocyte donation cycles from July 2003 to August 2005 were retrospectively evaluated and analyzed to determine if either resulted in a cleavage stage (n = 30) or blastocyst (n = 45) ET. The primary outcomes measured pregnancy rates, the percent development of HQ blastocysts based on day 3 embryo status, and the ability to select day 3 embryos suitable for transfer among four blinded evaluators by assessing their day 6 embryo outcome.

RESULTS

Cleavage stage ET resulted in significantly lower pregnancy rates, clinical pregnancy rates, and implantation rates (47% [n = 14/30]; 40% [n = 12/30] and 27 + or - 7%) compared to blastocyst stage (82% [n = 37/45]; 73% [n = 33/45] and 64 + or - 6% [+ or -SE], P < 0.01). In total, HQ blastocysts resulted from high and good quality day 3 embryos 35% (191/546) and 17% (93/546), respectively. Blinded evaluation revealed at least one, two or all three day 3 embryos were correctly selected for ET on day 6, 97%, 67% and 19%, respectively.

CONCLUSION

Day 6 ET resulted in significantly better clinical outcomes compared to day 3 ET. While day 3 status is not predictive of blastocyst quality, the selection of at least one day 3 embryo ultimately suitable for blastocyst ET underscores the significance of optimal endometrial receptivity.

Aneuploidy in rabbit males: semen traits and fertility

Chromosomal analyses were performed from peripheral blood samples from 20 adult rabbit males from Line R. This line has been selected for growth rate after weaning through 25 generations. Seminal characteristics and reproductive outcomes from these males were also examined. The chromosomal analysis results showed that one male had an aneuploidy rate of 16% (male A). The aneuploidies found represented both hypo- and hyper- haploidy. Differences between the male A and the contemporary males (males N), in fertility at 12 days post-insemination (44% vs. 66%) and at birth (31% vs. 59%) were observed. The male A also showed a high percentage of pregnancy losses (29% vs. 12%). For seminal characteristics, the percentage of abnormal spermatozoa was statistically different (P<0.05) between male A and males N (34+/-4 vs. 18+/-2), and concentration differed significantly between males, showing the male A reduced fewer spermatozoa than males N (67+/-23 vs. 172+/-10, x106/ml). Motility and kinematic parameters revealed no differences between males. Differences between male reproductive performance found in this study could be explained by the effect of aneuploidy on spermatogenesis and its deleterious effect on male reproduction.

Pronuclear morphology, embryo development and chromosome constitution

The aim of the present study was to evaluate the usefulness of pronuclear patterns, according to the classifications of Tesarik and Scott, as predictors of embryo chromosome constitution. Up to 73 preimplantation genetic diagnosis/preimplantation genetic screening (PGD/PGS) cycles were analysed in this retrospective study including 17 cycles of translocation carriers and 56 PGS cycles. A total of 331 biopsied embryos were studied assessing pronuclear (PN) pattern, embryo quality and chromosome constitution. As regards to the relationship between PN pattern and embryo quality, the data obtained in this study show no correlation between both parameters. Although there were no significant differences when comparing the distribution of chromosomally normal and abnormal embryos with respect to embryo quality, such differences were observed when distinguishing between normal, aneuploid and polyploid embryos. The results show that the PN pattern using Tesarik's and Scott's classification systems is not related to the embryo developmental potential or its chromosome constitution. Therefore, in the context of a PGD/PGS programme, the PN pattern cannot be used as a tool to predict embryo quality or chromosome status.

Association of BRCA1 mutations with occult primary ovarian insufficiency: a possible explanation for the link between infertility and breast/ovarian cancer risks

PURPOSE

Germline mutations in BRCA genes are associated with breast and ovarian cancer susceptibility. Because infertility is associated with breast and ovarian cancer risks, we hypothesized that the mutations in the BRCA gene may be associated with low response to fertility treatments.

METHODS

We performed ovarian stimulation in 126 women with breast cancer by using letrozole and gonadotropins for the purpose of fertility preservation by embryo or oocyte cryopreservation. As surrogates of ovarian reserve, the oocyte yield and the incidence of low response were compared with ovarian stimulation according to BRCA mutation status.

RESULTS

Of the 82 women who met the inclusion criteria, 47 women (57%) had undergone BRCA testing, and 14 had a mutation in BRCA genes, of which two were of clinically undetermined significance. In BRCA mutation-positive patients, low ovarian response rate was significantly higher compared with BRCA mutation-negative patients (33.3 v 3.3%; P = .014) and with BRCA-untested women (2.9%; P = .012). All BRCA mutation-positive low responders had BRCA1 mutations, but low response was not encountered in women who were only BRCA2 mutation positive. Compared with controls, BRCA1 mutation- but not BRCA2 mutation-positive women produced lower numbers of eggs (7.4 [95% CI, 3.1 to 17.7] v 12.4 [95% CI, 10.8 to 14.2]; P = .025) and had as many as 38.3 times the odds ratio of low response (95% CI, 4.1 to 353.4; P = .001).

CONCLUSION

BRCA1 mutations are associated with occult primary ovarian insufficiency. This finding may, at least in part, explain the link between infertility and breast/ovarian cancer risks.

Incidence of chromosomal mosaicism in morphologically normal nonhuman primate preimplantation embryos

OBJECTIVE

To establish the exact rates of chromosomal mosaicism in morphologically normal rhesus macaque embryos by determining the chromosomal complement of all blastomeres.

DESIGN

Retrospective rhesus monkey IVF study.

SETTING

Academic laboratory and primate research center.

PATIENT(S)

Young fertile rhesus macaque females.

INTERVENTION(S)

Morphologically normal in vitro-produced rhesus macaque embryos were dissociated and cytogenetically assessed using a five-color fluorescent in situ hybridization assay developed for rhesus macaque chromosomes homologous to human chromosomes 13, 16, 18, X, and Y.

MAIN OUTCOME MEASURE(S)

The incidence and extent of chromosomal mosaicism in rhesus macaque preimplantation embryos.

RESULT(S)

Seventy-seven preimplantation embryos, displaying normal morphology and development, from 17 young rhesus macaque females were analyzed. Overall, 39 embryos (50.6%) were normal, 14 embryos (18.2%) were completely abnormal, and 24 embryos (31.2%) were mosaic. Of the 226 blastomeres analyzed in the mosaic group, 110 blastomeres (48.7%) were normal.

CONCLUSION(S)

The observed rate of mosaicism in good-quality rhesus embryos resembles previously documented frequencies in poor-quality human preimplantation embryos. A high incidence of mosaicism may limit the diagnostic accuracy of preimplantation genetic diagnosis.

Expected poor ovarian response in predicting cumulative pregnancy rates: a powerful tool

Poor ovarian response in IVF cycles is associated with poor pregnancy rates. Expected poor responders may represent the worst prognostic group. Data were used from 222 patients starting the first of three IVF treatment cycles. The predictability of ongoing pregnancy after three cycles was analysed using survival analysis and hazard rate ratios. If first cycle poor responders were also predicted to have a poor response, they were classified as expected poor responders. The predicted pregnancy rate in cycles 2 and 3 for women with an observed poor response in the first cycle was approximately 24% for women aged 30 years and approximately 14% for women aged 40 years. For women with an expected poor response these rates were 12% and 6%, respectively. In contrast, women aged 40 years with an unexpected poor response still had a predicted cumulative pregnancy rate of 24%. Age as a sole predictor of cumulative pregnancy does not help to identify poor prognosis cases. Cumulative pregnancy rates in subsequent cycles for patients with an observed poor response in the first cycle may be a reason to refrain from further treatment. However, if such poor response has been expected, further treatment may be avoided because of an unfavourable prognosis for pregnancy.

Prediction of embryonic developmental competence by time-lapse observation and 'shortest-half' analysis

Selecting an embryo with the highest probability of achieving a pregnancy is a major challenge. Early-cleavage embryos are considered to be of good quality; however, the exact developmental stage that predicts further development has not been defined. The aim of the study was to characterize cleavage rate and distribution of various stages of mouse preimplantation embryos using a time-lapse system. Mated mice were killed 20 h after human chorionic gonadotrophin administration and putative zygotes were recovered and cultured in an incubator-enclosed time-lapse imaging system. The 'shortest half' analysis was used to establish the period in which at least 50% of the embryonic population cleaved within the shortest time. Analysis indicated that through embryonic development, cleavage timing becomes less uniform and the 'shortest half' becomes longer with intervals of 2, 2.5, 3.5 and 5 h for 2-, 4-, 8-cell embryo and blastocyst stages, respectively. The 'shortest half' for the first cleavage was closely synchronized, with 80% of embryos developing to the blastocyst stage. Moreover, slow-cleaving embryos approaching the 2-cell stage expressed inferior developmental potential in comparison to those cleaving within the 'shortest half'. Thus, embryonic cleavage rate seems to be a biological indicator of developmental potential and may be useful for embryo selection.

First polar body and nucleolar precursor body morphology is related to the ovarian reserve of infertile women

This study was undertaken in order to gain insight into the morphology of the first polar body (PB1) and the two pronuclei (2PN) in ICSI patients, specifically the nucleolar precursor bodies (NPB). Whether early abnormalities in these structures are related to the ovarian reserve of infertile women was also studied. Eighty consecutive infertile women were prospectively investigated throughout their first ICSI cycles. Basal ovarian reserve studies were performed in all women. Cycles were evaluated with respect to PB1 and 2PN morphology of the transferred embryos. Cycles that had at least one transferred embryo with normal PB1 and 2PN morphology had significantly better basal ovarian reserve parameters compared with cycles in which all transferred embryos had abnormal PB1 and 2PN morphology. Moreover, the normal morphology group performed significantly better throughout the ovarian stimulation, compared with the abnormal morphology group. Furthermore, the clinical implantation and pregnancy rates were significantly higher in the normal compared with the abnormal morphology group, corresponding to 20.7% versus 10.6% and 42.4% versus 18.2%, respectively. The study concluded that the morphology of the PB1 in metaphase II oocytes as well as that of the NPB within the 2PN zygotes seems to be related to the ovarian reserve in infertile women.

Chromosomal instability in rhesus macaque preimplantation embryos

OBJECTIVE

To establish a relevant animal model to systematically investigate chromosomal instability in human oocytes and preimplantation embryos.

DESIGN

Prospective rhesus monkey IVF study.

SETTING

Academic laboratory, Oregon National Primate Research Center and Caribbean Primate Research Center.

ANIMAL(S)

Young rhesus macaque females.

INTERVENTION(S)

In vitro produced entire rhesus macaque preimplantation embryos were cytogenetically assessed using a five-color fluorescent in situ hybridization assay developed for rhesus macaque chromosomes homologous to human chromosomes 13, 16, 18, X, and Y, using human bacterial artificial chromosome probes.

MAIN OUTCOME MEASURE(S)

Chromosomal abnormality rates in preimplantation embryos from young rhesus macaque females were established.

RESULT(S)

Fifty preimplantation embryos, displaying good morphology and normal development, were analyzed from 11 young rhesus macaque females. Overall, 27 embryos (54%) were normal, 11 embryos (22%) mosaic, 3 embryos (6%) chaotic, 2 embryos (4%) aneuploid, 3 embryos (6%) haploid, and 4 embryos (8%) triploid.

CONCLUSION(S)

These data indicate that in vitro produced rhesus macaque and human preimplantation embryos exhibit similar numerical chromosomal aberrations. Rhesus macaques appear to be a suitable animal model for investigating the origin of chromosomal instability observed in human preimplantation embryos.

High and low BMI increase the risk of miscarriage after IVF/ICSI and FET

BACKGROUND

The extremes of BMI are associated with an increased risk of miscarriage both in spontaneously conceived pregnancies and after fertility treatment. The aim of the present study was to study the effect of BMI on miscarriage rate (MR) in fresh IVF/ICSI, and in spontaneous and hormonally substituted frozen-thawed embryo (FET) cycles.

METHODS

Analysis was carried out on 3330 first pregnancy cycles, performed during the years 1999-2004, of which 2198 were fresh, 666 were spontaneous and 466 were hormonally substituted FET cycles. A categorical, a linear and a quadratic models of the effect of BMI on miscarriage were studied by logistic regression. Factors related to patient characteristics, protocol and embryo parameters were also examined.

RESULTS

MR was higher in hormonally substituted FET (23.0%), compared with the fresh cycles (13.8%) and spontaneous FET (11.4%, P < 0.0001). Multivariate logistic regression revealed that the relationship between BMI and the risk of miscarriage is not linear but quadratic (U-shaped) (P = 0.01), indicating a higher risk of miscarriage in underweight and obese women. Hormonal substitution for FET was also associated with a 1.7-fold higher MR, compared with the fresh cycles (P = 0.002, 95% confidence interval 1.2-2.3).

CONCLUSIONS

Obese and underweight women have an increased risk of miscarriage, and hormonally substituted FET is associated with an even higher MR.

Human blastocyst morphological quality is significantly improved in embryos classified as fast on day 3 (≥10 cells), bringing into question current embryological dogma

OBJECTIVE

To evaluate developmental potential of fast cleaving day 3 embryos.

DESIGN

Retrospective analysis.

SETTING

Academic reproductive center.

PATIENT(S)

Three thousand five hundred twenty-nine embryos.

INTERVENTION(S)

Day 3 embryos were classified according to cell number: slow cleaving: <or=6 cells, intermediate cleaving: 7-9 cells, and fast cleaving: >or=10 cells, and further evaluated on day 5. The preimplantation genetic diagnosis (PGD) results of 43 fast cleaving embryos were correlated to blastocyst formation. Clinical outcomes of transfers involving only fast cleaving embryos (n = 4) were evaluated.

MAIN OUTCOME MEASURE(S)

Blastocyst morphology correlated to day 3 blastomere number. Relationship between euploidy and blastocyst formation of fast cleaving embryos. Implantation, pregnancy (PR), and birth rates resulting from fast embryo transfers.

RESULT(S)

Blastocyst formation rate was significantly greater in the intermediate cleaving (72.7%) and fast cleaving (54.2%) groups when compared to the slow cleaving group (38%). Highest quality blastocysts were formed significantly more often in the fast cleaving group. Twenty fast cleaving embryos that underwent PGD, formed blastocysts, of which 45% (9/20) were diagnosed as euploid. Aneuploidy was diagnosed in 82.6% (19/23) of arrested embryos. A 50% implantation and 100% PR and birth rate were achieved with embryo transfers involving fast cleaving embryos.

CONCLUSION(S)

Fast cleaving embryos not only reach the blastocyst stage at a similar rate to intermediate cleaving embryos, but also exceed morphological quality criteria on day 5. Fast cleaving embryo transfers demonstrated a high clinical potential.