The analysis of one or two blastomeres for PGD using fluorescence in-situ hybridization

Preimplantation Genetic Testing for Aneuploidy: A Review

Importance

Preimplantation genetic testing for aneuploidy (PGT-A) has undergone many technical developments over recent years, including changes in biopsy timings, methodology, and genetic analysis techniques. The evidence surrounding the efficaciousness of PGT-A is sporadic and inconsistent; as such, significant doubt and concern remain regarding its widespread implementation.

Objective

This review seeks to describe the historical development of PGT-A and to analyze and summarize the current published literature.

Conclusions

At times during its infancy, PGT-A failed to display conclusive improvements in results; with newer technologies, PGT-A appears to yield superior outcomes, including reductions in miscarriages and multiple gestations. Clinicians and patients should assess the use of PGT-A on a case-by-case basis, with laboratories encouraged to utilize blastocyst biopsy and next-generation sequencing when conducting PGT-A. Further studies providing cumulative live birth rates and time to live birth are required if PGT-A is to be proven as producing superior outcomes.

Relevance

PGT-A has the potential ability to impact in vitro fertilization success rates, and as it is increasingly adopted worldwide, it is crucial that clinicians are aware of the evidence for its continued use.

Evaluation of the impact of sperm morphology on embryo aneuploidy rates in a donor oocyte program

This study investigates the correlation between sperm morphology and the incidence of embryo aneuploidy in an oocyte donation program. A total of 1,165 embryos from 103 patients have been analyzed by fluorescent in situ hybridization (FISH) for numerical abnormalities in chromosome numbers 13, 18, 21, X, and Y. Data has been evaluated in five groups according to sperm morphology, which has been assessed according to the Kruger's strict criteria. The results did not show any difference in paternal (p = 0.878), maternal (p = 0.873), and donor ages (p = 0.871), sperm counts (p = 0.782) and motility (p = 0.124), and fertilization rate (p = 0.080) among the groups. However, total aneuploidy rate (p < 0.001) and its derivatives (trisomy p = 0,042, monosomy p = 0,004) differed significantly and they were reversibly correlated with sperm morphology (rho correlation test; total aneuploidy p < 0.001, trisomy p < 0.001, monosomy p = 0.004). Therefore, these results suggested that diminished sperm quality is correlated to the aneuploidy rate in preimplantation embryos.

ABBREVIATIONS

FISH: fluorescence in situ hybridization; ICSI: intracytoplasmic sperm injection; HCG: human chorionic gonadotropin.

The Past, Present, and Future of Preimplantation Genetic Testing

Preimplantation genetic testing (PGT) of oocytes and embryos is the earliest form of prenatal testing. PGT requires in vitro fertilization for embryo creation. In the past 25 years, the use of PGT has increased dramatically. The indications of PGT include identification of embryos harboring single-gene disorders, chromosomal structural abnormalities, chromosomal numeric abnormalities, and mitochondrial disorders; gender selection; and identifying unaffected, HLA-matched embryos to permit the creation of a savior sibling. PGT is not without risks, limitations, or ethical controversies. This review discusses the techniques and clinical applications of different forms of PGT and the debate surrounding its associated uncertainty and expanded use.

Number of biopsied trophectoderm cells is likely to affect the implantation potential of blastocysts with poor trophectoderm quality

OBJECTIVE

To evaluate whether the developmental potential of the blastocyst is affected by the number of trophectoderm (TE) cells biopsied in preimplantation genetic diagnosis (PGD) cycles.

DESIGN

Retrospective study.

SETTING

University-affiliated center.

PATIENT(S)

Women underwent PGD cycles of blastocyst biopsy and fluorescence in situ hybridization analysis.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Biopsied TE cell number of blastocysts, survival, and implantation rates.

RESULT(S)

The biopsied TE cell number was affected by the TE quality and experience of different embryologists. The diagnostic efficiency increased when from one to five cells were biopsied (86.7%, 91.7%%, 96.0%, 96.8%, to 98.7%) and was maximized when more than six cells were biopsied. To compare the clinical efficiencies, blastocysts were divided into four groups according to biopsied TE cell number: 1-5, 6-10, 11-15, and 16-41. For the blastocysts with grade A TE score, no significant difference was observed in the survival and implantation rates among the four groups. For the blastocysts with grades B and C TE scores, the survival rates showed no significant differences among the four groups, but a significant decreasing trend in implantation rates was observed with increasing biopsied TE cell number.

CONCLUSION(S)

The implantation potential is negatively affected by the biopsied TE cell number in blastocysts with poor TE morphological score.

Temporal and developmental-stage variation in the occurrence of mitotic errors in tripronuclear human preimplantation embryos

Mitotic errors during early development of human preimplantation embryos are common, rendering a large proportion of embryos chromosomally mosaic. It is also known that the percentage of diploid cells in human diploid-aneuploid mosaic embryos is higher at the blastocyst than at the cleavage stage. In this study, we examined whether there is temporal and/or developmental-stage variation in the occurrence of mitotic errors in human preimplantation embryos from the first day of development onward using mitotically stable digynic tripronuclear human embryos as a model system. All the cells of the 114 digynic tripronuclear human preimplantation embryos included were analyzed by fluorescence in situ hybridization for chromosomes 1, 13, 16, 17, 18, 21, X, and Y. Embryos were grouped according to day of development (1-6) and developmental stage (2-cell to blastocyst stage). The possibility of a mitotic error was highest in the first and second mitotic divisions. The percentage of cells with mitotic errors increased during preimplantation development and was highest at the 9-16 cell stage (76%, P = 0.027). Thereafter, the percentage of cells with mitotic errors decreased to 64% at the morula and 56% at the blastocyst stage. The pattern found correlates with the activation of the embryonic genome at the 8-16 cell stage. A better insight in the timing of occurrence of mitotic errors in human preimplantation embryos could help in understanding and prevention of these errors and is relevant in the context of PGS.

Preimplantation genetic diagnosis for chromosome rearrangements - one blastomere biopsy versus two blastomere biopsy

PURPOSE

Preimplantation Genetic Diagnosis (PGD) has proven to be a useful reproductive option for carriers of some chromosome rearrangements. The data presented in this study compares the impact of one versus two blastomere biopsy on the likelihood of achieving a PGD result, as well as the effect on subsequent embryo development and clinical outcomes.

METHODS

IVF-PGD couples had either one or two blastomeres biopsied from all embryos with ≥7 blastomeres on day 3 post oocyte collection. These blastomeres were assessed for the specific chromosome rearrangement using Fluorescent In-situ Hybridisation (FISH). Further embryo development was monitored on days 4 and 5. Clinical outcomes were assessed retrospectively.

RESULTS

The data shows that statistically more embryos achieved a PGD result following two blastomere biopsy, compared with one blastomere biopsy (92 % versus 88 %, respectively). Furthermore it was found that embryo development and clinical outcomes were similar between the two biopsy groups.

CONCLUSIONS

Based on this analysis it appears that the biopsy of two blastomeres from embryos with ≥7 blastomeres on day 3 is a valid and successful approach for couples presenting for IVF-PGD for a chromosome rearrangement.

Preimplantation genetic screening: does it help or hinder IVF treatment and what is the role of the embryo?

Despite an ongoing debate over its efficacy, preimplantation genetic screening (PGS) is increasingly being used to detect numerical chromosomal abnormalities in embryos to improve implantation rates after IVF. The main indications for the use of PGS in IVF treatments include advanced maternal age, repeated implantation failure, and recurrent pregnancy loss. The success of PGS is highly dependent on technical competence, embryo culture quality, and the presence of mosaicism in preimplantation embryos. Today, cleavage stage biopsy is the most commonly used method for screening preimplantation embryos for aneuploidy. However, blastocyst biopsy is rapidly becoming the more preferred method due to a decreased likelihood of mosaicism and an increase in the amount of DNA available for testing. Instead of using 9 to 12 chromosome FISH, a 24 chromosome detection by aCGH or SNP microarray will be used. Thus, it is advised that before attempting to perform PGS and expecting any benefit, extended embryo culture towards day 5/6 should be established and proven and the clinical staff should demonstrate competence with routine competency assessments. A properly designed randomized control trial is needed to test the potential benefits of these new developments.

PGS-FISH in reproductive medicine and perspective directions for improvement: a systematic review

INTRODUCTION

Embryo selection can be carried out via morphological criteria or by using genetic studies based on Preimplantation Genetic Screening. In the present study, we evaluate the clinical validity of Preimplantation Genetic Screening with fluorescence in situ hybridization (PGS-FISH) compared with morphological embryo criteria.

MATERIAL AND METHODS

A systematic review was made of the bibliography, with the following goals: firstly, to determine the prevalence of embryo chromosome alteration in clinical situations in which the PGS-FISH technique has been used; secondly, to calculate the statistics of diagnostic efficiency (negative Likelihood Ratio), using 2 × 2 tables, derived from PGS-FISH. The results obtained were compared with those obtained from embryo morphology. We calculated the probability of transferring at least one chromosome-normal embryo when it was selected using either morphological criteria or PGS-FISH, and considered what diagnostic performance should be expected of an embryo selection test with respect to achieving greater clinical validity than that obtained from embryo morphology.

RESULTS

After an embryo morphology selection that produced a negative result (normal morphology), the likelihood of embryo aneuploidies was found to range from a pre-test value of 65% (prevalence of embryo chromosome alteration registered in all the study groups) to a post-test value of 55% (Confidence interval: 50-61), while after PGS-FISH with a negative result (euploid), the post-test probability was 42% (Confidence interval: 35-49) (p < 0.05). The probability of transferring at least one euploid embryo was the same whether 3 embryos were selected according to morphological criteria or whether 2, selected by PGS-FISH, were transferred. Any embryo selection test, if it is to provide greater clinical validity than embryo morphology, must present a LR-value of 0.40 (Confidence interval: 0.32-0.51) in single embryo transfer, and 0.06 (CI: 0.05-0.07) in double embryo transfer.

DISCUSSION

With currently available technology, and taking into account the number of embryos to be transferred, the clinical validity of PGS-FISH, although superior to that of morphological criteria, does not appear to be clinically relevant.

Preimplantation genetic screening: a systematic review and meta-analysis of RCTs

BACKGROUND

Preimplantation genetic screening (PGS) has increasingly been used in the past decade. Here we present a systematic review and meta-analysis of RCTs on the effect of PGS on the probability of live birth after IVF.

METHODS

PubMed and trial registers were searched for RCTs on PGS. Trials were assessed following predetermined quality criteria. The primary outcome was live birth rate per woman, secondary outcomes were ongoing pregnancy rate, miscarriage rate, multiple pregnancy rate and pregnancy outcome.

RESULTS

Nine RCTs comparing IVF with and without PGS were included in our meta-analysis. Fluorescence in situ hybridization was used in all trials and cleavage stage biopsy was used in all but one trial. PGS significantly lowered live birth rate after IVF for women of advanced maternal age (risk difference: -0.08; 95% confidence interval: -0. 13 to -0.03). For a live birth rate of 26% after IVF without PGS, the rate would be between 13 and 23% using PGS. Trials where PGS was offered to women with a good prognosis and to women with repeated implantation failure suggested similar outcomes.

CONCLUSIONS

There is no evidence of a beneficial effect of PGS as currently applied on the live birth rate after IVF. On the contrary, for women of advanced maternal age PGS significantly lowers the live birth rate. Technical drawbacks and chromosomal mosaicism underlie this inefficacy of PGS. New approaches in the application of PGS should be evaluated carefully before their introduction into clinical practice.

Meiotic segregation of Robertsonian translocations ascertained in cleavage-stage embryos--implications for preimplantation genetic diagnosis

BACKGROUND

The aim of this study was to ascertain the prevalence of meiotic segregation products in embryos from carriers of 13/14 and 14/21 Robertsonian translocations and to estimate the predictive value of testing single cells using the fluorescence in situ hybridization (FISH) technique, to provide more information for decision-making about PGD.

METHODS

In this prospective cohort study, the copy number of translocation chromosomes in nuclei from lysed blastomeres of cleavage-stage embryos was ascertained using locus-specific FISH probes. Logistic regression analysis, controlling for translocation type, female age and fertility status, was used to calculate the odds ratio (OR) of unbalanced segregation products for female and male heterozygotes. The primary diagnostic measure was the predictive value of the test result. The primary outcome measure was the live birth rate per couple.

RESULTS

Female carriers were four times more likely than male carriers to produce embryos with an unbalanced translocation product (OR 3.8, 95% confidence interval 2.0-7.2, P < 0.001). The prevalence of abnormality for the chromosomes tested in embryos from female or male heterozygotes was estimated to be 43 or 28%, respectively, while estimates of the predictive value were 93-100 or 96-100% for a normal test result and 79 or 57% for an abnormal test result. The live birth rate per couple was 58% for female carriers and 50% for male carriers.

CONCLUSIONS

For female carriers, PGD using FISH could reduce the risk of miscarriage from either translocation or the risk of Down syndrome from the 14/21 Robertsonian translocation. PGD using FISH for male carriers is unlikely to be indicated given the relatively low prevalence of chromosome imbalance and low predictive value.

Diagnostic accuracy: theoretical models for preimplantation genetic testing of a single nucleus using the fluorescence in situ hybridization technique

BACKGROUND

The aim of this study was to develop and use theoretical models to investigate the accuracy of the fluorescence in situ hybridization (FISH) technique in testing a single nucleus from a preimplantation embryo without the complicating effect of mosaicism.

METHODS

Mathematical models were constructed for three different applications of FISH in preimplantation genetic testing (sex determination for sex-linked diseases, two-way reciprocal translocations and sporadic chromosome aneuploidy). The input values were the degree of aneuploidy (initially set at 3% per chromosome for sporadic aneuploidy) and the accuracy per probe (initially set at 95%), defined as the proportion of normal diploid nuclei with a normal signal pattern. The primary statistic was the predictive value of the test result.

RESULTS

Testing two chromosome pairs to determine sex chromosome status or detect unbalanced translocation products had high predictive value: at least 99.5% for a normal test result (95% CI: 99-100%), and 90% for an abnormal test result (95% CI: 88-92%). However, the predictive value of an abnormal test result testing five chromosomes for sporadic chromosome aneuploidy was 41% (95% CI: 36-46%); 90% would be achieved with an aneuploidy rate per chromosome of 20.3% (equivalent to 99.5% prevalence for 23 chromosomes) rather than 3%, or with an accuracy per probe of 99.6% rather than 95%, or when testing 23 chromosome pairs, rather than 5 pairs, with either 8.3% aneuploidy (86.4% prevalence) or 99.5% accuracy.

CONCLUSIONS

Testing a single cell using the FISH technique has the potential to achieve acceptable analytical performance for sex determination and two-way reciprocal translocations, but is unlikely to achieve adequate performance testing for sporadic chromosome aneuploidy. New techniques for detecting the copy number of every chromosome are emerging, but it remains to be seen if the high accuracy required will be achieved.

Preimplantation genetic testing: indications and controversies

In the last two decades, the use of preimplantation genetic testing has increased dramatically. This testing is used for identifying singlegene disorders, chromosomal abnormalities, mitochondrial disorders, gender selection in non-mendelian disorders with unequal gender distribution, aneuploidy screening, and other preconceptually identified genetic abnormalities in prospective parents. Genetic testing strategies and diagnostic accuracy continues to improve, but not without risks or controversies. In this review the authors discuss the techniques and clinical application of preimplantation genetic diagnosis, and the debate surrounding its associated uncertainty and expanded use.

Single-cell DNA and FISH analysis for application to preimplantation genetic diagnosis

Preimplantation genetic testing, which includes preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS), is a form of a very early prenatal testing. The goal of this method is to avoid transfer of embryos affected with a specific genetic disease or condition. This unit describes the steps involved in amplifying DNA from a single blastomere and specific assays for detecting a variety of DNA mutations. For some assays, whole-genome amplification by primer-extension preamplification (PEP) is performed prior to analysis. Support protocols describe the biopsy of one or two blastomeres from the developing preimplantation embryo, isolation for further investigation of all blastomeres from embryos shown to have the mutant allele, and isolation of single lymphocytes or lymphoblastoid cells as models for single-cell DNA analysis. A procedure for FISH analysis on single interphase blastomeres is provided along with support protocols for probe preparation and probe validation, which is recommended as a preliminary step before performing any PGD or PGS FISH analysis.

Impact of cleavage-stage embryo biopsy in view of PGD on human blastocyst implantation: a prospective cohort of single embryo transfers

BACKGROUND

Human embryo biopsy is performed for preimplantation genetic diagnosis (PGD). The impact of 1- or 2-cell removal at cleavage-stage on future embryo development and implantation capacity is highly debated.

METHODS

In order to explore this issue further, a cohort of Day 5 single embryo transfers was analysed prospectively for embryological and clinical outcome. All transferred embryos resulted from 8-cell embryos on Day 3, from which subsequently either one cell (group I, n = 182) or two cells (group II, n = 259) were removed, or on which no invasion by means of embryo biopsy was performed (group III, control group, n = 702). RESULTS Blastocyst formation was significantly better in group III compared with group II, and similar to group I. Group I and group II did not differ in Day 3 nor in Day 5 embryo development. The overall live birth rate was significantly higher in group I (37.4%, CI 29.0-47.4%) than in group II (22.4%, CI 17.0-28.9%), and comparable to the reference ICSI population (35.0%, CI 30.8-39.7%).

CONCLUSIONS

The clinical outcome of 1-cell biopsy was significantly better than that of 2-cell biopsy, even when adjusted for availability of genetically transferable embryos.

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.

What next for preimplantation genetic screening? More randomized controlled trials needed?

The recent debate on preimplantation genetic screening (PGS) has raised questions about its routine use in clinical practice. It has been suggested that the most effective way to resolve the debate about the usefulness of PGS is to perform more well-designed and well-executed randomized controlled trials (RCTs). However, in view of the lack of evidence for the effectiveness of PGS and the accumulating evidence for its harmfulness, it is our opinion that it is unethical to perform additional RCTs for the indication advanced maternal age using cleavage stage biopsy.

Dichorionic triamniotic triplet pregnancy with monozygotic twins discordant for trisomy 13 after preimplantation genetic screening: case report

OBJECTIVE

To report the first dichorionic triamniotic triplet pregnancy discordant for trisomy 13 after in vitro fertilization (IVF) treatment with preimplantation genetic screening (PGS).

DESIGN

Case report.

SETTING

Private IVF center.

PATIENT(S)

A 40-year-old para 1+6 woman.

INTERVENTION(S)

IVF combined with PGS for chromosomes 13, 16, 18, 21, and 22, resulting in the transfer of two embryos.

MAIN OUTCOME MEASURE(S)

Prenatal fetal ultrasonography revealed a dichorionic triamniotic triplet pregnancy. An amniocentesis, performed at 15-weeks' gestation, confirmed that the singleton and one monozygotic twin were normal but the other monozygotic twin was trisomy 13.

RESULT(S)

After diagnosis and counseling, selective termination of the trisomy 13 monozygotic twin was performed at 16 weeks and 4 days. At 18 weeks and 4 days the co-twin died. A healthy boy was delivered by elective caesarean section at 36-weeks' gestation.

CONCLUSION(S)

Assisted reproductive techniques that breach the embryo's zona pellucida such as assisted hatching and PGS embryo biopsy increase the incidence of monozygotic twins. Due to high levels of mosaicism in human preimplantation embryos, PGS cannot ensure that embryos diagnosed as normal and selected for transfer do not contain abnormal cells. Hence, further reports of discordant monozygotic twins following PGS are expected, emphasizing the need for appropriate counseling of patients wishing to embark on an IVF/PGS treatment cycle.

Derivation of embryonic stem cells for therapy: new technologies

Embryonic stem cells are currently derived from the inner cell mass of human blastocysts, generated from spare embryos donated for research. To overcome ethical concerns raised by destruction of the embryo, two groups of workers have attempted to derive these cells from isolated blastomeres of 8- to 10-cell stage embryos using the embryo biopsy method akin to that used in preimplantation diagnosis. This paper briefly discusses these two techniques in relation to the routine derivation of stem cells from blastocysts. Some embryological aspects of using the inner cell mass of blastocysts in preference to early embryonic cells are presented. The paper also considers some pitfalls in therapeutic cloning, especially in non-human primates, since legislation to allow this procedure for stem cell research is currently being passed in Australia.

Current value of preimplantation genetic aneuploidy screening in IVF

Preimplantation genetic aneuploidy screening (PGS) has been performed during the last decade as a way of enhancing embryo selection in patients with an increased incidence of embryonic numerical chromosome abnormalities (advanced maternal age, recurrent miscarriage and recurrent implantation failure). It has been proposed that the replacement of euploid embryos in these patients would result in a higher implantation and pregnancy rate and a reduced miscarriage rate. Additionally, the transfer of fewer embryos could reduce the chances for multiple pregnancies in all IVF patients. Although, to date, multiple studies have addressed this issue, contradictory results have been encountered. As a result, the effectiveness of aneuploidy screening remains to be established. Moreover, child outcome studies documenting the safety of this procedure are needed. The aim of this review is to summarize the available evidence concerning the use of PGS to determine the current value of the technique.

Preimplantation genetic screening for abnormal number of chromosomes (aneuploidies) in in vitro fertilisation or intracytoplasmic sperm injection

BACKGROUND

In both in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI), selection of the most competent embryo(s) for transfer is generally based on morphological criteria. However, many women fail to achieve a pregnancy after transfer of good quality embryos. One of the presumed causes is that such morphologically normal embryos show an abnormal number of chromosomes (aneuploidies). In preimplantation genetic screening (PGS), embryos are analysed for aneuploidies and only embryos that are euploid for the chromosomes tested are transferred. This technique has been suggested and used to improve pregnancy rates for the following indications: (i) advanced maternal age, (ii) repeated IVF failure, (iii) repeated miscarriage and (iv) testicular sperm extraction (TESE)-ICSI. Although PGS is used more and more often, its effectiveness is still unclear.

OBJECTIVES

To assess the effectiveness of PGS in terms of live births in women undergoing IVF or ICSI treatment.

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders and Subfertility Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 1, 2005), MEDLINE (1966 to present) and EMBASE (1980 to present) (searched March 2005) and reference lists of articles. We also contacted authors for providing additional data when necessary.

SELECTION CRITERIA

Trials for all four suggested indications as mentioned above were sought. All relevant published randomised controlled trials were selected. They were eligible for inclusion if the comparison dealt with IVF/ICSI with PGS versus IVF/ICSI without PGS.

DATA COLLECTION AND ANALYSIS

Relevant data were extracted independently by two authors. All trials were screened and analysed according to predetermined quality criteria. Validity was assessed in terms of method of randomisation, completeness of follow-up, intention-to-treat analysis and presence or absence of blinding. The primary outcome measure was live birth rate per woman. Secondary outcome measures were the proportion of women reaching embryo transfer, mean number of embryos transferred per transfer, clinical pregnancy rate, multiple pregnancy rate, miscarriage rate, ongoing pregnancy rate, proportion of women reaching embryo transfer after cryopreservation and proportion of women whose child has a congenital malformation.

MAIN RESULTS

Two randomised controlled trials met our predetermined eligibility criteria. These trials used PGS for advanced maternal age. The primary outcome of live birth rate per woman was not significantly different in the PGS and control groups, though data were only available from one study. The live birth rate was 11% (21 out of 199) in the PGS group, versus 15% (29 out of 190) in the control group (OR 0.65; 95% CI 0.36 to 1.19). For a control group rate of 15%, these data suggest a live birth rate using PGS of between 4% and 17%. Ongoing pregnancy rate was provided in both studies. This was not significantly different with a combined odds ratio of 0.64 (95% CI 0.37 to 1.09). For a control group rate of 20%, this suggests an ongoing pregnancy rate using PGS of between 8% and 21%.

AUTHORS' CONCLUSIONS

To date there is insufficient data to determine whether PGS is an effective intervention in IVF/ICSI for improving live birth rates. Available data on PGS for advanced maternal age showed no difference in live birth rate and ongoing pregnancy rate. However, only two randomised trials were found, of which one included only 39 patients. For both studies comments on their methodological quality can be made. Therefore more properly conducted randomised controlled trials are needed. Until such trials have been performed PGS should not be used in routine patient care.