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1.  On-Site Array CGH Applications in Clinical In Vitro Fertilization: Reproductive Outcomes and Impact on Cryopreservation of Non-transferred Human Embryos 
Background: IVF pregnancy rates have trended upward although gains have been accompanied by unwelcome increases in pre-term delivery and multiple gestation. These adverse outcomes happen because multiple embryos are typically transferred during IVF. Integrating newer molecular cytogenetic techniques with IVF can optimize selection of a single embryo for transfer. Methods: The SurePlex DNA amplification system (BlueGnome Ltd; Cambridge, UK) was used on-site for whole genome amplification of human blastocyst trophectoderm (TE) cells obtained by biopsy. IVF patients (initial cycle, age <35, no prior miscarriage, normal karyotype) were prospectively randomized into two groups: In Group 1, embryos were selected on the basis of morphology and comprehensive chromosomal screening via array comparative genomic hybridization (aCGH) from d5 TE biopsy, while Group 2 embryos were assessed by morphology only. All patients underwent a single fresh blastocyst transfer on d6. For embryos in the aCGH group, only one euploid blastocyst was selected for transfer and surplus euploid blastocysts were vitrified. In the non-aCGH (control) group, a single blastocyst was selected for fresh transfer based on appearance only, with vitrification of any surplus blastocysts with satisfactory morphology. Results: Aneuploidy was identified in 191/425 of Group 1 balstocysts (44.9%). Control embryos (n=389) were assessed by microscopy only. A higher clinical pregnancy rate was observed in Group 1 patients compared to the control group (70.9 vs. 45.8%; p = 0.017). Only 64 (28.3%) surplus euploid embryos were frozen in Group 1 while 157 (40.4%) blastocysts were cryopreserved for Group 2 (p=0.017). Conclusion: These data underscore the intrinsic imprecision of IVF when conventional morphology is used alone to select embryos for transfer. Embryos evaluated with aCGH implant with greater efficiency and achieve clinical pregnancy more often than those selected without aCGH. Patients should be advised that aCGH screening may reduce the number of surplus embryos for cryopreservation.
PMCID: PMC3635430
2.  Selection of euploid blastocysts for cryopreservation with array comparative genomic hybridization (aCGH) results in increased implantation rates in subsequent frozen and thawed embryo transfer cycles 
Background
In assisted reproductive treatments, embryos remaining after fresh embryo transfer are usually selected for cryopreservation based on traditional morphology assessment. Our previous report has demonstrated that array comparative genomic hybridization (aCGH) screening for IVF patients with good prognosis significantly improves clinical and ongoing pregnancy rates in fresh embryo transfer cycles. The current study further investigates the efficiency of applying aCGH in the selection of euploid embryos for cryopreservation as related to pregnancy and implantation outcomes in subsequent frozen embryo transfer (FET) cycles.
Methods
First-time IVF patients with good prognosis undergoing fresh single embryo transfer and having at least one remaining blastocyst for cryopreservation were prospectively randomized into two groups: 1) Group A patients had embryos assessed by morphology first and then by aCGH screening of trophectoderm cells and 2) Group B patients had embryos evaluated by morphology alone. All patients had at least one blastocyst available for cryopreservation after fresh embryo transfer. There were 15 patients in Group A and 23 patients in Group B who failed to conceive after fresh embryo transfer and completed the FET cycles. Blastocyst survival and implantation rates were compared between the two groups.
Results
There were no significant differences in blastocyst survival rates between Group A and Group B (90.9% vs. 91.3%, respectively; p >0.05). However, a significantly higher implantation rate was observed in the morphology assessment plus aCGH screening group compared to the morphology assessment alone group (65.0% vs. 33.3%, respectively; p = 0.038). There was no miscarriage observed in Group A while a 16.7% miscarriage rate was recorded in Group B (0% vs. 16.7%, respectively; p >0.05).
Conclusions
While aCGH screening has been recently applied to select euploid blastocysts for fresh transfer in young, low-risk IVF patients, this is the first prospective study on the impact of aCGH specifically on blastocyst survival and implantation outcomes in the subsequent FET cycles of IVF patients with good prognosis. The present study demonstrates that aCGH screening of blastocysts prior to cryopreservation significantly improves implantation rates and may reduce the risk of miscarriage in subsequent FET cycles. Further randomized clinical studies with a larger sample size are needed to validate these preliminary findings.
doi:10.1186/1755-8166-6-32
PMCID: PMC3766007  PMID: 23937723
aCGH; Trophectoderm biopsy; Cryopreservation; Implantation
3.  Selection of single blastocysts for fresh transfer via standard morphology assessment alone and with array CGH for good prognosis IVF patients: results from a randomized pilot study 
Background
Single embryo transfer (SET) remains underutilized as a strategy to reduce multiple gestation risk in IVF, and its overall lower pregnancy rate underscores the need for improved techniques to select one embryo for fresh transfer. This study explored use of comprehensive chromosomal screening by array CGH (aCGH) to provide this advantage and improve pregnancy rate from SET.
Methods
First-time IVF patients with a good prognosis (age <35, no prior miscarriage) and normal karyotype seeking elective SET were prospectively randomized into two groups: In Group A, embryos were selected on the basis of morphology and comprehensive chromosomal screening via aCGH (from d5 trophectoderm biopsy) while Group B embryos were assessed by morphology only. All patients had a single fresh blastocyst transferred on d6. Laboratory parameters and clinical pregnancy rates were compared between the two groups.
Results
For patients in Group A (n = 55), 425 blastocysts were biopsied and analyzed via aCGH (7.7 blastocysts/patient). Aneuploidy was detected in 191/425 (44.9%) of blastocysts in this group. For patients in Group B (n = 48), 389 blastocysts were microscopically examined (8.1 blastocysts/patient). Clinical pregnancy rate was significantly higher in the morphology + aCGH group compared to the morphology-only group (70.9 and 45.8%, respectively; p = 0.017); ongoing pregnancy rate for Groups A and B were 69.1 vs. 41.7%, respectively (p = 0.009). There were no twin pregnancies.
Conclusion
Although aCGH followed by frozen embryo transfer has been used to screen at risk embryos (e.g., known parental chromosomal translocation or history of recurrent pregnancy loss), this is the first description of aCGH fully integrated with a clinical IVF program to select single blastocysts for fresh SET in good prognosis patients. The observed aneuploidy rate (44.9%) among biopsied blastocysts highlights the inherent imprecision of SET when conventional morphology is used alone. Embryos randomized to the aCGH group implanted with greater efficiency, resulted in clinical pregnancy more often, and yielded a lower miscarriage rate than those selected without aCGH. Additional studies are needed to verify our pilot data and confirm a role for on-site, rapid aCGH for IVF patients contemplating fresh SET.
doi:10.1186/1755-8166-5-24
PMCID: PMC3403960  PMID: 22551456
4.  Comparing thaw survival, implantation and live birth rates from cryopreserved zygotes, embryos and blastocysts 
CONTEXT:
Most in vitro fertilization (IVF) programs employ embryo cryopreservation to enhance pregnancies from a single ovarian stimulation. More embryos are created, some of which are not transferred to the uterus immediately, generating a need for improved cryopreservation protocols. One protocol may involve growing embryos to a further stage of development, allowing only embryos with proven developmental capabilities to be cryopreserved. Here we examined thaw survival, implantation and live birth rates of embryos cryopreserved at different stages.
AIMS:
We examined thaw survival, implantation and live birth rates of embryos cryopreserved at the zygote, day 3 (D3) embryos or blastocyst stage.
SETTINGS AND DESIGN:
This is a retrospective study from a single academic IVF program.
PATIENTS AND METHODS:
A retrospective study of all patients who had frozen embryos transferred to their uteri from year 2002 to 2008 at a single academic IVF program was conducted.
STATISTICAL ANALYSIS USED:
Analysis of variance followed by Fisher's Exact Test was performed to compare the survival after thaw, implantation and live birth rates between the three groups.
RESULTS:
One thousand nine hundred and ninety-one zygotes, 2880 D3 embryos and 503 blastocysts were frozen using a slow freeze technique, thawed and transferred. Significantly more D3 embryos and blastocysts survived the thawing process compared to zygotes and significantly higher implantation rate per number of thawed blastocysts was achieved than that for zygotes. Live birth rates were similar between the three groups.
CONCLUSIONS:
Growing embryos to blastocyst stage prior to cryopreservation is associated with fewer frozen embryos but does not appear compromise patients’ chance of achieving pregnancy
doi:10.4103/0974-1208.82356
PMCID: PMC3136065  PMID: 21772736
Blastocyst; embryo cryopreservation; frozen embryo transfer; implantation; in vitro fertilization; slow-freeze; zygote
5.  Selection of competent blastocysts for transfer by combining time-lapse monitoring and array CGH testing for patients undergoing preimplantation genetic screening: a prospective study with sibling oocytes 
BMC Medical Genomics  2014;7:38.
Background
Recent advances in time-lapse monitoring in IVF treatment have provided new morphokinetic markers for embryonic competence. However, there is still very limited information about the relationship between morphokinetic parameters, chromosomal compositions and implantation potential. Accordingly, this study aimed at investigating the effects of selecting competent blastocysts for transfer by combining time-lapse monitoring and array CGH testing on pregnancy and implantation outcomes for patients undergoing preimplantation genetic screening (PGS).
Methods
A total of 1163 metaphase II (MII) oocytes were retrieved from 138 PGS patients at a mean age of 36.6 ± 2.4 years. These sibling MII oocytes were then randomized into two groups after ICSI: 1) Group A, oocytes (n = 582) were cultured in the time-lapse system and 2) Group B, oocytes (n = 581) were cultured in the conventional incubator. For both groups, whole genomic amplification and array CGH testing were performed after trophectoderm biopsy on day 5. One to two euploid blastocysts within the most predictive morphokinetic parameters (Group A) or with the best morphological grade available (Group B) were selected for transfer to individual patients on day 6. Ongoing pregnancy and implantation rates were compared between the two groups.
Results
There were significant differences in clinical pregnancy rates between Group A and Group B (71.1% vs. 45.9%, respectively, p = 0.037). The observed implantation rate per embryo transfer significantly increased in Group A compared to Group B (66.2% vs. 42.4%, respectively, p = 0.011). Moreover, a significant increase in ongoing pregnancy rates was also observed in Group A compared to Group B (68.9% vs. 40.5%. respectively, p = 0.019). However, there was no significant difference in miscarriage rate between the time-lapse system and the conventional incubator (3.1% vs. 11.8%, respectively, p = 0.273).
Conclusions
This is the first prospective investigation using sibling oocytes to evaluate the efficiency of selecting competent blastocysts for transfer by combining time-lapse monitoring and array CGH testing for PGS patients. Our data clearly demonstrate that the combination of these two advanced technologies to select competent blastocysts for transfer results in improved implantation and ongoing pregnancy rates for PGS patients.
doi:10.1186/1755-8794-7-38
PMCID: PMC4077552  PMID: 24954518
Time-lapse monitoring; Array CGH; PGS; Ploidy; Implantation; Miscarriage
6.  Comparative Genomic Hybridization Selection of Blastocysts for Repeated Implantation Failure Treatment: A Pilot Study 
BioMed Research International  2014;2014:457913.
The aim of this study is to determine if the use of preimplantation genetic screening (PGS) by array comparative genomic hybridization (array CGH) and transfer of a single euploid blastocyst in patients with repeated implantation failure (RIF) can improve clinical results. Three patient groups are compared: 43 couples with RIF for whom embryos were selected by array CGH (group RIF-PGS), 33 couples with the same history for whom array CGH was not performed (group RIF NO PGS), and 45 good prognosis infertile couples with array CGH selected embryos (group NO RIF PGS). A single euploid blastocyst was transferred in groups RIF-PGS and NO RIF PGS. Array CGH was not performed in group RIF NO PGS in which 1-2 blastocysts were transferred. One monoembryonic sac with heartbeat was found in 28 patients of group RIF PGS and 31 patients of group NO RIF PGS showing similar clinical pregnancy and implantation rates (68.3% and 70.5%, resp.). In contrast, an embryonic sac with heartbeat was only detected in 7 (21.2%) patients of group RIF NO PGS. In conclusion, PGS by array CGH with single euploid blastocyst transfer appears to be a successful strategy for patients with multiple failed IVF attempts.
doi:10.1155/2014/457913
PMCID: PMC3980987  PMID: 24779011
7.  Ovarian hyperstimulation syndrome and prophylactic human embryo cryopreservation: analysis of reproductive outcome following thawed embryo transfer 
Objective
To review utilisation of elective embryo cryopreservation in the expectant management of patients at risk for developing ovarian hyperstimulation syndrome (OHSS), and report on reproductive outcome following transfer of thawed embryos.
Materials and methods
Medical records were reviewed for patients undergoing IVF from 2000–2008 to identify cases at risk for OHSS where cryopreservation was electively performed on all embryos at the 2 pn stage. Patient age, total number of oocytes retrieved, number of 2 pn embryos cryopreserved, interval between retrieval and thaw/transfer, number (and developmental stage) of embryos transferred (ET), and delivery rate after IVF were recorded for all patients.
Results
From a total of 2892 IVF cycles undertaken during the study period, 51 IVF cases (1.8%) were noted where follicle number exceeded 20 and pelvic fluid collection was present. Elective embryo freeze was performed as OHSS prophylaxis in each instance. Mean (± SD) age of these patients was 32 ± 3.8 yrs. Average number of oocytes retrieved in this group was 23 ± 8.7, which after fertilisation yielded an average of 14 ± 5.7 embryos cryopreserved per patient. Thaw and ET was performed an average of 115 ± 65 d (range 30–377 d) after oocyte retrieval with a mean of 2 ± 0.6 embryos transferred. Grow-out to blastocyst stage was achieved in 88.2% of cases. Delivery/livebirth rate was 33.3% per initiated cycle and 43.6% per transfer. Non-transferred blastocysts remained in cryostorage for 24 of 51 patients (46.1%) after ET, with an average of 3 ± 3 blastocysts refrozen per patient.
Conclusion
OHSS prophylaxis was used in 1.8% of IVF cycles at this institution; no serious OHSS complications were encountered during the study period. Management based on elective 2 pn embryo cryopreservation with subsequent thaw and grow-out to blastocyst stage for transfer did not appear to compromise embryo viability or overall reproductive outcome. For these patients, immediate elective embryo cryopreservation and delay of ET by as little as 30 d allowed for satisfactory conclusion of the IVF sequence, yielding a livebirth-delivery rate (per ET) >40%.
doi:10.1186/1757-2215-1-7
PMCID: PMC2585559  PMID: 19014420
8.  Live birth following serial vitrification of embryos and PGD for fragile X syndrome in a patient with the premutation and decreased ovarian reserve 
Purpose
To present a live birth resulting from serial vitrification of embryos and pre-implantation genetic diagnosis (PGD).
Methods
A 31-year-old with primary infertility, fragile-X premutation, and decreased ovarian reserve (DOR) (baseline FSH level 33 IU/L), presented after failing to stimulate to follicle diameters >10 mm with three cycles of invitro fertilization (IVF). After counseling, the couple opted for serial in-vitro maturation (IVM), embryo vitrification, and genetic testing using array comparative genomic hybridization (aCGH) and PGD. Embryos were vitrified 2 days after intra-cytoplasmic sperm injection (ICSI). Thawed embryos were biopsied on day-three and transferred on day-five.
Results
The couple underwent 20 cycles of assisted reproductive technology. A total of 23 in-vivo mature and five immature oocytes were retrieved, of which one matured in-vitro. Of 24 embryos, 17/24 (71 %) developed to day two and 11/24 (46 %) survived to blastocyst stage with a biopsy result available. Four blastocysts had normal PGD and aCGH results. Both single embryo transfers resulted in a successful implantation, one a blighted ovum and the other in a live birth.
Conclusions
Young patients with DOR have potential for live birth as long as oocytes can be obtained and embryos created. Serial vitrification may be the mechanism of choice in these patients when PGD is needed.
doi:10.1007/s10815-013-0079-x
PMCID: PMC3879937  PMID: 24062195
In-vitro maturation (IVM); Embryo vitrification; Diminished Ovarian Reserve (DOR); Fragile X Syndrome (FXS); Preimplantation Genetic Diagnosis (PGD); Array Comparative Genomic Hybridization (aCGH)
9.  An update of preimplantation genetic diagnosis in gene diseases, chromosomal translocation, and aneuploidy screening 
Preimplantation genetic diagnosis (PGD) is gradually widely used in prevention of gene diseases and chromosomal abnormalities. Much improvement has been achieved in biopsy technique and molecular diagnosis. Blastocyst biopsy can increase diagnostic accuracy and reduce allele dropout. It is cost-effective and currently plays an important role. Whole genome amplification permits subsequent individual detection of multiple gene loci and screening all 23 pairs of chromosomes. For PGD of chromosomal translocation, fluorescence in-situ hybridization (FISH) is traditionally used, but with technical difficulty. Array comparative genomic hybridization (CGH) can detect translocation and 23 pairs of chromosomes that may replace FISH. Single nucleotide polymorphisms array with haplotyping can further distinguish between normal chromosomes and balanced translocation. PGD may shorten time to conceive and reduce miscarriage for patients with chromosomal translocation. PGD has a potential value for mitochondrial diseases. Preimplantation genetic haplotyping has been applied for unknown mutation sites of single gene disease. Preimplantation genetic screening (PGS) using limited FISH probes in the cleavage-stage embryo did not increase live birth rates for patients with advanced maternal age, unexplained recurrent abortions, and repeated implantation failure. Polar body and blastocyst biopsy may circumvent the problem of mosaicism. PGS using blastocyst biopsy and array CGH is encouraging and merit further studies. Cryopreservation of biopsied blastocysts instead of fresh transfer permits sufficient time for transportation and genetic analysis. Cryopreservation of embryos may avoid ovarian hyperstimulation syndrome and possible suboptimal endometrium.
doi:10.5653/cerm.2011.38.3.126
PMCID: PMC3283069  PMID: 22384431
Array Comparative Genomic Hybridization; Preimplantation Genetic Diagnosis; Preimplantation Genetic Screening; Single Nucleotide Polymorphisms Array; Vitrification; Whole Genome Amplification; Human
10.  Vitrification of mouse embryos at 2-cell, 4-cell and 8-cell stages by cryotop method 
Purpose
The objective of this study was to investigate the effects of vitrification on the preimplantation developmental competence of mouse 2-cell, 4-cell and 8-cell stage embryos.
Methods
Mouse 2-cell, 4-cell and 8-cell stage embryos were cryopreserved using the cryotop vitrification method and subsequently warmed on a later date. The embryos were then assessed by their morphology, blastocyst formation and hatching rates. Additionally, trophectoderm (TE) and inner cell mass (ICM) cell numbers were compared in hatched blastocysts from the control and experimental groups.
Results
Vitrified embryos at the 2-cell, 4-cell and 8-cell stages appeared morphologically normal after warming. The overall survival rate of vitrified embryos at various stages after warming was 96.7% and there were no significant differences among 2-cell stage (96.0%), 4-cell stage (96.8%) and 8-cell stage (97.1%) embryos (P > 0.05). The blastocyst formation rate (69.4%) and hatching rate (52.6%) of vitrified 2-cell embryos were significantly lower than that from the control group and vitrified 8-cell embryos (P < 0.05). In the vitrified 4-cell embryo group, the blastocyst formation rate (90.3%) was similar to the 8-cell group (91.2%), but the hatching rate (60.0%) was significantly lower than that of the non-vitrified control ( 84.1%) and vitrified 8-cell embryo (78.4%) groups (P < 0.05). When further development to the fully hatched blastocyst stage was compared, hatched blastocysts derived from vitrified 2-cell, 4-cell and 8-cell embryos had significantly lower cell counts both in the ICM and TE, as compared to fresh blastocysts (P < 0.05). Among the vitrified 2-cell, 4-cell and 8-cell embryo groups, there were no significant differences in the cell counts of ICM and TE (P > 0.05).
Conclusions
Although cryotop vitrification was suitable for the cryopreservation of mouse embryos from the 2-cell stage, 4-cell stage and 8-cell stage without significant loss of survival, vitrification had an adverse effect on the development of 2-cell embryos. Mouse embryos at the 8-cell stage had the best tolerance for vitrification and would yield the highest level of post-vitrification developmental competence among early cleavage stage embryos. Nevertheless, it is unclear how these findings can be extrapolated to human embryos.
doi:10.1007/s10815-009-9370-2
PMCID: PMC2799565  PMID: 19967554
Vitrification; Cleavage; Embryos; Development; Cryopreservation; Mouse
11.  Comparison of clinical outcomes between fresh embryo transfers and frozen-thawed embryo transfers 
Background: Advances in embryo culture technology and cryopreservation have led to a shift in in vitro fertilization (IVF) from early fresh or frozen-thawed cleavage embryo transfer to fresh or frozen-thawed blastocyst stage transfer.
Objective: To compare the clinical outcomes of fresh embryo transfers and frozen-thawed embryo transfers.
Materials and Methods: In this retrospective case control study, patients undergoing IVF cycles from January 2012 to December 2012 were enrolled in Assisted Reproduction of Wuhan Union Hospital were enrolled. A total of 1891 cycle contains 1150 fresh embryo transfers and 741 frozen-thawed embryo transfers were studied. All data were transferred directly to SPSS 18 and analyzed.
Results: Clinical pregnancy rates of fresh cleavage-stage embryo transfers compared with fresh blastocyst transfers, frozen-thawed cleavage-stage embryo transfers, post thaw cleavage-stage extended blastocyst culture transfers and frozen-thawed blastocyst transfers were 52.7%, 35.88%, 35.29%, 47.75%, 59.8% in patients under 35 years of ages and 41.24%, 26.92%, 11.32%, 46.15%, 55.8% in patients older than 35 years old, respectively. The multiple pregnancy rates, abortion rates and ectopic pregnancy rates did not differ significantly among the five groups.
Conclusion: The clinical pregnancy rates were not different significantly between fresh cleavage-stage embryo transfers and fresh blastocyst transfers. But the clinical pregnancy rate of frozen-thawed blastocyst transfer was the highest among fresh/frozen-thawed embryo transfers.
PMCID: PMC4111889  PMID: 25071849
In vitro fertilization; Embryo transfer; Clinical outcome; Ectopic pregnancy; Endometrial receptivity
12.  New Tools for Embryo Selection: Comprehensive Chromosome Screening by Array Comparative Genomic Hybridization 
BioMed Research International  2014;2014:517125.
The objective of this study was to evaluate the usefulness of comprehensive chromosome screening (CCS) using array comparative genomic hybridization (aCGH). The study included 1420 CCS cycles for recurrent miscarriage (n = 203); repetitive implantation failure (n = 188); severe male factor (n = 116); previous trisomic pregnancy (n = 33); and advanced maternal age (n = 880). CCS was performed in cycles with fresh oocytes and embryos (n = 774); mixed cycles with fresh and vitrified oocytes (n = 320); mixed cycles with fresh and vitrified day-2 embryos (n = 235); and mixed cycles with fresh and vitrified day-3 embryos (n = 91). Day-3 embryo biopsy was performed and analyzed by aCGH followed by day-5 embryo transfer. Consistent implantation (range: 40.5–54.2%) and pregnancy rates per transfer (range: 46.0–62.9%) were obtained for all the indications and independently of the origin of the oocytes or embryos. However, a lower delivery rate per cycle was achieved in women aged over 40 years (18.1%) due to the higher percentage of aneuploid embryos (85.3%) and lower number of cycles with at least one euploid embryo available per transfer (40.3%). We concluded that aneuploidy is one of the major factors which affect embryo implantation.
doi:10.1155/2014/517125
PMCID: PMC4022197  PMID: 24877108
13.  Cryopreservation of Embryos, Blastocysts, and Pregnancy Rates of Blastocysts Derived from Frozen-Thawed Embryos and Frozen-Thawed Blastocysts 
Purpose: To evaluate the development of cryopreserved embryos when thawed and subsequently cultured to the blastocyst stage in comparison to transferring cryopreserved blastocysts.
Methods: In this retrospective clinical study, we have evaluated 170 cycles in patients undergoing IVF treatment for infertility. Cryopreserved embryos were thawed and were subsequently cultured and transferred at the blastocyst stage. Cryopreserved blastocysts (Day 6) were thawed and transferred immediately.
Results: Five hundred and sixty embryos and 444 blastocysts have been thawed. In the embryos group, the survival rate was 89% while in the blastocyst group the survival rate was 56%. In the embryos group the blastocyst development rate was 24.5%. The implantation rate in the embryos group was 20.6% per group blastocyst transferred compared to 5.3% in the blastocyst group.
Conclusions: The ability of cryopreserved embryos to develop to blastocysts and their implantation potential does not seem to be greatly affected by the cryopreservation procedure.
doi:10.1023/A:1013138703680
PMCID: PMC3455699  PMID: 11804424
blastocyst; cryopreservation; embryos; implantation rate; pregnancy rate
14.  Clinical effectiveness of elective single versus double embryo transfer: meta-analysis of individual patient data from randomised trials 
Objective To compare the effectiveness of elective single embryo transfer versus double embryo transfer on the outcomes of live birth, multiple live birth, miscarriage, preterm birth, term singleton birth, and low birth weight after fresh embryo transfer, and on the outcomes of cumulative live birth and multiple live birth after fresh and frozen embryo transfers.
Design One stage meta-analysis of individual patient data.
Data sources A systematic review of English and non-English articles from Medline, Embase, and the Cochrane Central Register of Controlled Trials (up to 2008). Additional studies were identified by contact with clinical experts and searches of bibliographies of all relevant primary articles. Search terms included embryo transfer, randomised controlled trial, controlled clinical trial, single embryo transfer, and double embryo transfer.
Review methods Comparisons of the clinical effectiveness of cleavage stage (day 2 or 3) elective single versus double embryo transfer after fresh or frozen in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) treatments were included. Trials were included if the intervention differed only in terms of the intended number of embryos to be transferred. Trials that involved only blastocyst (day five) transfers were excluded.
Results Individual patient data were received for every patient recruited to all eight eligible trials (n=1367). A total of 683 and 684 women randomised to the single and double embryo transfer arms, respectively, were included in the analysis. Baseline characteristics in the two groups were comparable. The overall live birth rate in a fresh IVF cycle was lower after single (181/683, 27%) than double embryo transfer (285/683, 42%) (adjusted odds ratio 0.50, 95% confidence interval 0.39 to 0.63), as was the multiple birth rate (3/181 (2%) v 84/285 (29%)) (0.04, 0.01 to 0.12). An additional frozen single embryo transfer, however, resulted in a cumulative live birth rate not significantly lower than the rate after one fresh double embryo transfer (132/350 (38%) v 149/353 (42%) (0.85, 0.62 to 1.15), with a minimal cumulative risk of multiple birth (1/132 (1%) v 47/149 (32%)). The odds of a term singleton birth (that is, over 37 weeks) after elective single embryo transfer was almost five times higher than the odds after double embryo transfer (4.93, 2.98 to 8.18).
Conclusions Elective single embryo transfer results in a higher chance of delivering a term singleton live birth compared with double embryo transfer. Although this strategy yields a lower pregnancy rate than a double embryo transfer in a fresh IVF cycle, this difference is almost completely overcome by an additional frozen single embryo transfer cycle. The multiple pregnancy rate after elective single embryo transfer is comparable with that observed in spontaneous pregnancies.
doi:10.1136/bmj.c6945
PMCID: PMC3006495  PMID: 21177530
15.  Blastocyst development rate impacts outcome in cryopreserved blastocyst transfer cycles 
Fertility and sterility  2008;90(6):2138-2143.
Structured Abstract
Objective
To assess cycle outcome among day 5 and day 6 cryopreserved frozen-thawed blastocyst embryo transfers (FBET).
Design
Retrospective cohort study.
Setting
Military-based ART center.
Patients
One hundred seventy-two non-donor, programmed cryopreserved embryo cycles.
Interventions
Fully expanded blastocysts on day 5 were cryopreserved on day 5 and those achieving this state on day 6 were cryopreserved on day 6. Leuprolide acetate was given for ovulation inhibition and endometrial supplementation was by oral and vaginal estradiol. Progesterone in oil was administered and blastocyst transfer occurred in the morning of the 6th day of progesterone.
Main Outcome Measures
Implantation, pregnancy and live birth rates.
Results
Fresh and frozen cycle characteristics were similar between groups. Day 5 FBET had significantly higher implantation rates (32.2% vs. 19.2%; p=0.01) which remained significant even when adjusting for co-variates (OR: 1.91; 95%CI: 1.00, 3.67). Live birth rates trended towards improvement after adjusting for co-variates (OR: 1.18; 95%CI: 0.61, 2.30).
Conclusions
Cryopreserved day 5 blastocysts have higher implantation rates and trend toward improved pregnancy outcomes compared to cryopreserved day 6 blastocysts. This suggests that embryo development rate may, in part, predict implantation and subsequent FBET outcomes although embryos not achieving the blastocyst stage until day 6 still demonstrate acceptable outcomes.
doi:10.1016/j.fertnstert.2007.10.029
PMCID: PMC2613799  PMID: 18178191
frozen-thawed blastocyst cycle; embryo transfer; day 5 vs. day 6
16.  Predictive value of preimplantation genetic diagnosis for aneuploidy screening in repeated IVF-ET cycles among women with recurrent implantation failure 
Objective
To determine the predictive value of euploid embryos in women with recurrent implantation failure undergoing repeated IVF-ET cycles with PGD (PGD).
Design
Cohort of IVF-PGD cycles in a tertiary care ART facility.
Materials and method(s)
Fifty-five consecutive patients with repeated implantation failure (more than three failed IVF-ET cycles) underwent two or more PGD cycles for aneuploidy testing. Mean maternal age was 37.6 ± 5.3 years. Biopsies were performed on day 3. One blastomere was removed from each pre-embryo, fixed and analyzed by multicolor and multi-probe FISH for chromosomes X and Y, 13, 15, 16, 17, 18, 21, and 22.
Result(s)
Forty-three of 55 patients (78%) undergoing PGD had at least one euploid embryo for transfer. Of these 31 patients (72%) also had at least one euploid embryo available for transfer with the second cycle. Of the 12 (28%) patients with no euploid embryos available for transfer with the second IVF/PGD cycle, five had a third cycle of PGD and two of these had euploid embryos available for transfer. Seventeen of the 31 patients (55%) who had euploid embryos on the second PGD cycle conceived. The ongoing pregnancy and implantation rates in patients with at least one euploid embryo were 40% and 18%, respectively. Twelve of the 55 patients (22%) had no euploid embryos available for transfer on the first PGD cycle, but on the second PGD cycle, six (50%) of these had euploid embryos for transfer. Only two pregnancies were achieved among this group of women, yielding a pregnancy rate of 17%, but both conceptions resulted in miscarriage. Of the six patients with no euploid embryos available after the second PGD cycle, four patients had a third IVF/PGD cycle, but none had euploid embryos available for transfer. Also, among women with euploid embryos available only in either the first or second PGD cycle, but not both, no ongoing pregnancy was achieved. No woman who had a PGD cycle productive of no euploid embryos had an ongoing pregnancy. Significant differences were found in terms of ongoing pregnancy (40%, P < 0.05) and implantation rates (18%, P < 0.05) in women with euploid embryos available for transfer with the first and second IVF/PGD cycles, compared to women with no euploid embryos available for transfer with either the first or second cycle. The positive predictive value of the first euploid cycle predicting a second euploid cycle was 72%, 95% CI 0.66–0.78. The negative predictive value of an aneuploid cycle was 50%, 95% CI 0.27–0.72. The sensitivity and specificity of the first PGD cycle predicting the second was 84%, 95% CI 0.77–0.91 and 33%, 95% CI 0.18–0.48, respectively.
Conclusion(s)
Even with a history of recurrent implantation failure, the availability of euploid embryos, especially on two, consecutive PGD cycles is associated with high ongoing pregnancy and implantation rates. Conversely, the absence of euploid embryos for transfer predicts poor reproductive outcome, even if subsequent cycles do yield euploid embryos.
doi:10.1007/s10815-008-9200-y
PMCID: PMC2582115  PMID: 18266102
Aneuploidy; Recurrent IVF failure; Multicolor FISH; Preimplantation genetic diagnosis
17.  Successful implantation and live birth of a healthy boy after triple biopsy and double vitrification of oocyte-embryo-blastocyst 
SpringerPlus  2015;4:22.
Introduction
Preimplantation genetic diagnosis and/or screening (PGD/PGS) allow the assessment of the genetic health of an embryo before transferring it into the uterus. These techniques require the removal of cellular material (polar bodies, blastomere(s) or trophectoderm cells) in order to perform the proper genetic analysis. We report the implantation and live birth outcome of a vitrified-warmed blastocyst developed after triple biopsy and double vitrification procedures at oocyte, cleavage embryo and blastocyst stage.
Case description
An infertile couple, with family history of β-thalassemia, searched for IVF procedure and PGD. First polar bodies biopsy with subsequent vitrification was uninformative due to meiotic crossing-over, so oocytes were inseminated after warming. Two embryos were obtained and blastomere biopsy was performed on day 3 with inconclusive results on their genetic status. Their culture resulted in one expanded blastocyst stage on day 7 that underwent trophectoderm biopsy and vitrification. This embryo showed to be normal. It was then warmed and transferred in an artificial cycle.
Discussion and Evaluation
Preconception genetic analysis by removal and analysis of the first polar body is technically possible, but the genetic information that we can obtain at this stage may be limited and the oocytes to be inseminated is not predictable. Compared to blastomere biopsy, trophectoderm biopsy has more diagnostic efficiency with respect to both chromosomal mosaicism and PCR accuracy, reducing the problems of amplification failure and allele drop out. Moreover, embryos biopsied at the cleavage stage seem to have lower implantation rate than biopsied blastocyst.
Conclusions
This is the first case report of a live birth obtained from a three step biopsy and double vitrification procedures of a blastocyst. This case report seems also to suggest the harmlessness of all these procedures if carefully performed by a skilled biologist in an IVF lab with quality management system. Finally, our study highlight that blastocyst cryopreserved on day 7 have clinically important potential and embryos that not reach blastocyst stage on day 6 should not to be discharged because they may result in an ongoing pregnancy.
doi:10.1186/s40064-015-0788-y
PMCID: PMC4300308  PMID: 25625041
Vitrification; Polar body biopsy; Embryo biopsy; Blastocyst biopsy
18.  Polar body based aneuploidy screening is poorly predictive of embryo ploidy and reproductive potential 
Purpose
Polar body (polar body) biopsy represents one possible solution to performing comprehensive chromosome screening (CCS). This study adds to what is known about the predictive value of polar body based testing for the genetic status of the resulting embryo, but more importantly, provides the first evaluation of the predictive value for actual clinical outcomes after embryo transfer.
Methods
SNP array was performed on first polar body, second polar body, and either a blastomere or trophectoderm biopsy, or the entire arrested embryo. Concordance of the polar body-based prediction with the observed diagnoses in the embryos was assessed. In addition, the predictive value of the polar body -based diagnosis for the specific clinical outcome of transferred embryos was evaluated through the use of DNA fingerprinting to track individual embryos.
Results
There were 459 embryos analyzed from 96 patients with a mean maternal age of 35.3. The polar body-based predictive value for the embryo based diagnosis was 70.3 %. The blastocyst implantation predictive value of a euploid trophectoderm was higher than from euploid polar bodies (51 % versus 40 %). The cleavage stage embryo implantation predictive value of a euploid blastomere was also higher than from euploid polar bodies (31 % versus 22 %).
Conclusion
Polar body based aneuploidy screening results were less predictive of actual clinical outcomes than direct embryo assessment and may not be adequate to improve sustained implantation rates. In nearly one-third of cases the polar body based analysis failed to predict the ploidy of the embryo. This imprecision may hinder efforts for polar body based CCS to improve IVF clinical outcomes.
doi:10.1007/s10815-014-0293-1
PMCID: PMC4156943  PMID: 25106935
Preimplantation genetic screening (PGS); Polar bodies; Aneuploidy; Blastocyst; SNP array
19.  Polar body array CGH for prediction of the status of the corresponding oocyte. Part I: clinical results 
Human Reproduction (Oxford, England)  2011;26(11):3173-3180.
BACKGROUND
Several randomized controlled trials have not shown a benefit from preimplantation genetic screening (PGS) biopsy of cleavage-stage embryos and assessment of up to 10 chromosomes for aneuploidy. Therefore, a proof-of-principle study was planned to determine the reliability of alternative form of PGS, i.e. PGS by polar body (PB) biopsy, with whole genome amplification and microarray-based comparative genomic hybridization (array CGH) analysis.
METHODS
In two centres, all mature metaphase II oocytes from patients who consented to the study were fertilized by ICSI. The first and second PBs (PB1and PB2) were biopsied and analysed separately for chromosome copy number by array CGH. If either or both of the PBs were found to be aneuploid, the corresponding zygote was then also processed by array CGH for concordance analysis.
RESULTS
Both PBs were biopsied from a total of 226 zygotes from 42 cycles (average 5.5 per cycle; range 1–15) in 41 couples with an average maternal age of 40.0 years. Of these, the ploidy status of the zygote could be predicted in 195 (86%): 55 were euploid (28%) and 140 were aneuploid (72%). With only one exception, there was at least one predicted aneuploid zygote in each cycle and in 19 out of 42 cycles (45%), all zygotes were predicted to be aneuploid. Fresh embryos were transferred in the remaining 23 cycles (55%), and one frozen transfer was done. Eight patients had a clinical pregnancy of which seven were evolutive (ongoing pregnancy rates: 17% per cycle and 30% per transfer). The ploidy status of 156 zygotes was successfully analysed by array CGH: 38 (24%) were euploid and 118 (76%) were aneuploid. In 138 cases complete information was available on both PBs and the corresponding zygotes. In 130 (94%), the ploidy status of the zygote was concordant with the ploidy status of the PBs and in 8 (6%), the results were discordant.
CONCLUSIONS
This proof-of-principle study indicates that the ploidy of the zygote can be predicted with acceptable accuracy by array CGH analysis of both PBs.
doi:10.1093/humrep/der294
PMCID: PMC3196878  PMID: 21908463
microarray CGH analysis; polar body; oocyte; zygote; PGS
20.  Low utilization of extra embryos in donor oocyte in vitro fertilization cycles: an ethical dilemma to donor management 
Purpose
To explore outcomes of donor In Vitro Fertilization (IVF) cycles with regards to cryopreservation and utilization of extra embryos after fresh transfer.
Methods
A database search was performed to identify all consecutive fresh donor oocyte cycles from January 1, 2000 to December 31, 2010 at a private fertility laboratory. Parameters analyzed included: number of oocytes retrieved, number of patients choosing embryo cryopreservation, number of patients returning for frozen embryo transfer (FET), and pregnancy outcomes.
Results
A total of 1070 fresh oocyte donor cycles were identified. Average number of oocytes retrieved was 16.9 ± 7.9, and average number of embryos transferred was 2.3 ± 0.96. Sixty-six percent of patients cryopreserved excess embryos following fresh transfer, and only 40 % of these patients ultimately returned for FET. Patients who conceived in their fresh cycle were much less likely to return for FET than those who did not (25 % v 65 %, p < 0.001), however chance of conceiving with FET was no different between these two groups (38 % v 38 %, NS).
Conclusions
An unexpectedly low number of patients undergoing a donor oocyte IVF cycle will ultimately return to utilize extra embryos from their fresh cycle. This is concerning considering the high numbers of oocytes retrieved and the known complications from hyperstimulation, especially in light of the relatively high pregnancy rates associated with donor cycles. This raises concerns not only for donor management, but also raises ethical dilemmas when considering the large numbers of remaining embryos that will never be utilized.
doi:10.1007/s10815-013-0038-6
PMCID: PMC3790114  PMID: 23812846
Embryo donation; Embryo utilization; Cryopreservation; Embryo surplus
21.  Lessons from elective in vitro fertilization (IVF) in, principally, non-infertile women 
Background
We here report the first investigation of exclusively elective in vitro fertilization (IVF) cycles in women with no apparent history of infertility. Since IVF outcome in women with infertility are always influenced by underlying causes of infertility, a study on non-infertile women may offer new insights.
Methods
We investigated 88 females without history of infertility in 109 consecutive elective IVF cycles, almost exclusively performed for purposes of preimplantation genetic screening (PGS; i.e., elective gender selection). The following questions were addressed: (i) impact of PGS on IVF pregnancy chances; (ii) impact of transfer of 1 vs. ≥2 embryos on IVF pregnancy chances; (iii) correlation of anti-Müllerian hormone (AMH) levels to embryo ploidy (iv) effect of gonadotropin dosage used in stimulation on available embryos for transfer; and (v) in form of a 1:1 case control study, compared 33 elective PGS cycles with matched control cycles without PGS, performed in couples with either prior tubal ligations and/or severe male factor infertility as indication of IVF.
Results
The overall clinical pregnancy rate for the group was 36.7%; pregnancy was associated with number of euploid (P = 0.009) and number of embryos transferred (P = 0.001). Odds of pregnancy were 3.4-times higher if ≥4 euploid embryos were produced in comparison to <4 (95% CI 1.2 to 9.2; P = 0.019), and odds of pregnancy were 6.6-times higher if greater than or equal to 2 rather than <1 euploid embryos were transferred (95% CI 2.0 to 21.7; P = 0.002). Increasing AMH (P = 0.001) and gonadotropin dosage used in ovarian stimulation (P = 0.024), was, independently, associated with number of available euploid embryos. Increasing AMH, but not follicle stimulating hormone (FSH), was associated with number of embryos available for biopsy and PGS (P = 0.0001). Implantation rates were 26.4% with PGS and 9.5% without (P = 0.008). Women undergoing PGS, demonstrated 4.58-times higher odds of pregnancy than matched controls (95% CI 1.102 to 19.060, Exp 4.584, P = 0.036).
Conclusions
This study suggests that outcomes of elective IVF cycles may significantly deviate from infertility-associated cycles. Affirming proof of concept for PGS, utilizing day-3 embryo biopsy and fluorescence in-situ hybridization (FISH), both widely held responsible for earlier failures to establish such proof, suggests that the principal cause of prior failures were likely not insufficient laboratory techniques but poor patient selection for PGS. Such a conclusion questions the current reintroduction of PGS with improved techniques and technologies in absence of prior determination of suited patient populations.
doi:10.1186/1477-7827-10-48
PMCID: PMC3495227  PMID: 22716082
In vitro fertilization (IVF); Preimplantation genetic diagnosis (PGD); Preimplantation genetic screening (PGS); Aneuploidy; Pregnancy rates; Gonadotropin dosage; Anti-Müllerian hormone (AMH); Single embryo transfer
22.  Live birth after fresh embryo transfer vs elective embryo cryopreservation/frozen embryo transfer in women with polycystic ovary syndrome undergoing IVF (FreFro-PCOS): study protocol for a multicenter, prospective, randomized controlled clinical trial 
Trials  2014;15:154.
Background
Polycystic ovary syndrome (PCOS) patients are at increased risk of pregnancy complications, which may impair pregnancy outcome. Transfer of fresh embryos after superovulation may lead to abnormal implantation and placentation and further increase risk for pregnancy loss and complications. Some preliminary data suggest that elective embryo cryopreservation followed by frozen–thawed embryo transfer into a hormonally primed endometrium could result in a higher clinical pregnancy rate than that achieved by fresh embryo transfer.
Methods/Design
This study is a multicenter, prospective, randomized controlled clinical trial (1:1 treatment ratio of fresh vs. elective frozen embryo transfers).. A total of 1,180 infertile PCOS patients undergoing the first cycle of in vitro fertilization (IVF) or intracytoplasmic sperm injection will be enrolled and randomized into two parallel groups. Participants in group A will undergo fresh embryo transfer on day 3 after oocyte retrieval, and participants in group B will undergo elective embryo cryopreservation after oocyte retrieval and frozen–thawed embryo transfer in programmed cycles. The primary outcome is the live birth rate. Our study is powered at 80 to detect an absolute difference of 10 at the significance level of 0.01 based on a two-sided test.
Discussion
We hypothesize that elective embryo cryopreservation and frozen–thawed embryo transfer will reduce the incidence of pregnancy complications and increase the live birth rate in PCOS patients who need IVF to achieve pregnancy.
Trial registration
ClinicalTrials.gov Identifier: NCT01841528
doi:10.1186/1745-6215-15-154
PMCID: PMC4022358  PMID: 24885793
Frozen–thawed embryo transfer; In vitro fertilization; Live birth; Polycystic ovarian syndrome
23.  Arrested human embryos are more likely to have abnormal chromosomes than developing embryos from women of advanced maternal age 
Background
Aneuploidy is one of the major factors that result in low efficiency in human infertility treatment by in vitro fertilization (IVF). The development of DNA microarray technology allows for aneuploidy screening by analyzing all 23 pairs of chromosomes in human embryos. All chromosome screening for aneuploidy is more accurate than partial chromosome screening, as errors can occur in any chromosome. Currently, chromosome screening for aneuploidy is performed in developing embryos, mainly blastocysts. It has not been performed in arrested embryos and/or compared between developing embryos and arrested embryos from the same IVF cycle.
Methods
The present study was designed to examine all chromosomes in blastocysts and arrested embryos from the same cycle in patients of advanced maternal ages. Embryos were produced by routine IVF procedures. A total of 90 embryos (45 blastocysts and 45 arrested embryos) from 17 patients were biopsied and analyzed by the Agilent DNA array platform.
Results
It was found that 50% of the embryos developed to blastocyst stage; however, only 15.6% of the embryos (both blastocyst and arrested) were euploid, and most (84.4%) of the embryos had chromosomal abnormalities. Further analysis indicated that 28.9% of blastocysts were euploid and 71.1% were aneuploid. By contrast, only one (2.2%) arrested embryo was euploid while others (97.8%) were aneuploid. The prevalence of multiple chromosomal abnormalities in the aneuploid embryos was also higher in the arrested embryos than in the blastocysts.
Conclusions
These results indicate that high proportions of human embryos from patients of advanced maternal age are aneuploid, and the arrested embryos are more likely to have abnormal chromosomes than developing embryos.
doi:10.1186/1757-2215-7-65
PMCID: PMC4065243  PMID: 24955133
Aneuploidy; Arrested embryo; Blastocyst; Human
24.  SNP microarray-based 24 chromosome aneuploidy screening demonstrates that cleavage-stage FISH poorly predicts aneuploidy in embryos that develop to morphologically normal blastocysts 
Molecular Human Reproduction  2010;16(8):590-600.
Although selection of chromosomally normal embryos has the potential to improve outcomes for patients undergoing IVF, the clinical impact of aneuploidy screening by fluorescence in situ hybridization (FISH) has been controversial. There are many putative explanations including sampling error due to mosaicism, negative impact of biopsy, a lack of comprehensive chromosome screening, the possibility of embryo self-correction and poor predictive value of the technology itself. Direct analysis of the negative predictive value of FISH-based aneuploidy screening for an embryo's reproductive potential has not been performed. Although previous studies have found that cleavage-stage FISH is poorly predictive of aneuploidy in morphologically normal blastocysts, putative explanations have not been investigated. The present study used a single nucleotide polymorphism (SNP) microarray-based 24 chromosome aneuploidy screening technology to re-evaluate morphologically normal blastocysts that were diagnosed as aneuploid by FISH at the cleavage stage. Mosaicism and preferential segregation of aneuploidy to the trophectoderm (TE) were evaluated by characterization of multiple sections of the blastocyst. SNP microarray technology also provided the first opportunity to evaluate self-correction mechanisms involving extrusion or duplication of aneuploid chromosomes resulting in uniparental disomy (UPD). Of all blastocysts evaluated (n = 50), 58% were euploid in all sections despite an aneuploid FISH result. Aneuploid blastocysts displayed no evidence of preferential segregation of abnormalities to the TE. In addition, extrusion or duplication of aneuploid chromosomes resulting in UPD did not occur. These findings support the conclusion that cleavage-stage FISH technology is poorly predictive of aneuploidy in morphologically normal blastocysts.
doi:10.1093/molehr/gaq037
PMCID: PMC2907218  PMID: 20479065
FISH; PGD; microarray; mosaicism; uniparental isodisomy
25.  Single thawed euploid embryo transfer improves IVF pregnancy, miscarriage, and multiple gestation outcomes and has similar implantation rates as egg donation 
Purpose
The objective of our study was to determine if trophectoderm biopsy, vitrification, array-comparative genomic hybridization and single thawed euploid embryo transfer (STEET) can reduce multiple gestations and yield high pregnancy and low miscarriage rates.
Methods
We performed a retrospective observational study comparing single thawed euploid embryo to routine age matched in vitro fertilization (IVF) patients that underwent blastocyst transfer from 2008 to 2011 and to our best prognosis group donor oocyte recipients (Donor). Our main outcome measures were implantation rate, clinical pregnancy rate, spontaneous abortion rate and multiple gestation rate.
Results
The STEET group had a significantly higher implantation rate (58 %, 53/91) than the routine IVF group (39 %, 237/613) while the Donor group (57 %, 387/684) had a similar implantation rate. The clinical pregnancy rates were not statistically different between the STEET and IVF groups. However, the multiple gestation rate was significantly lower in the STEET group (STEET 2 % versus IVF 34 %, Donor 47 %).
Conclusions
STEET results in a high pregnancy rate, low multiple gestation rate and miscarriage rates. Despite the older age of STEET patients and transfer of twice as many embryos, the implantation rate for STEET was indistinguishable from that for egg donation. STEET offers an improvement to IVF, lowering risks without compromising pregnancy rate.
doi:10.1007/s10815-012-9929-1
PMCID: PMC3585677  PMID: 23307447
Trophectoderm biopsy; Single embryo transfer; Array-comparative genomic hybridization; Aneuploidy; Embryo biopsy; Donor egg; IVF; Embryo transfer

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