The predictive value of using a combined Z-score and day 3 embryo morphology score in the assessment of embryo survival on day 5

BACKGROUND: The purpose of this study was to evaluate the ability of using the Z-score alone, or, in combination with the day 3 embryo morphology score, to predict embryo viability at day 5 from a large cohort of embryos derived from patients undergoing treatment with IVF/ICSI. METHODS AND RESULTS: In this retrospective study, a total of 1894 zygotes from 346 treatment cycles (295 couples) was analysed between January 2001 and May 2002. The Z-scoring system was useful in predicting day 5 embryo survival. The mean +/- SD day 5 embryo survival rates were 78.2 +/- 1.7, 49.0 +/- 2.5, 21.4 +/- 3.2 and 11.8 +/- 5.6% for Z-1, Z-2, Z-3 and Z-4 zygotes groups respectively. Embryos derived from Z-1 scores and grade I day 3 embryo scores showed the best day 5 embryo survival and a very high implantation potential. CONCLUSIONS: These data suggest that a combined evaluation of the Z-score and day 3 embryo morphology is highly predictive of embryo outcome after IVF/ICSI. The Z-score could be of great help in the selection of embryos for cultures extended to later stages. The Z-score alone, or preferably in combination with day 3 embryo morphology, is useful in the determination of the most suitable embryos and the number of embryos for transfer, thus achieving the optimal chance of conception while reducing the risk of high order multiple pregnancy.     

Morphological evaluation of human embryos and derivation of an embryo quality scoring system specific for day 3 embryos: a preliminary study

A scoring system specific for day 3 embryos has not been extensively explored. Most IVF laboratories continue to grade embryos solely on the basis of cell number and percentage fragmentation as was traditionally done for day 2 embryos. Additional morphological features, some unique to day 3 embryos, may be useful in selecting embryos most likely to blastulate and implant. The objective of this study was to derive an embryo scoring system for day 3 transfers which is predictive of positive pregnancy outcomes. A total of 316 transferred embryos from 93 patients was recorded on videotape and evaluated. The following parameters were used to grade the embryos: cell number, fragmentation pattern (FP), cytoplasmic pitting, compaction, equal sized blastomeres, blastomere expansion and absence of vacuoles. The clinical pregnancy rate was 41.9%, with an implantation rate of 18% per embryo transferred. The mean number of embryos transferred per patient was 3.4. Three formulae were derived to score embryo quality in each transfer based on the average score of individual embryos transferred. In the first scoring system, cell number alone was used to predict pregnancy outcome. The second scoring system was based on blastomere number and the observed FP. The third scoring system utilized both blastomere number and FP but also combined this with five morphological criteria to yield a final day 3 embryo quality (D3EQ) score. We found the D3EQ score to be prognostic of pregnancy outcome. This study suggests that although cell number and FP are certainly predictors of positive pregnancy outcomes, additional parameters specific to day 3 embryos should be used to stratify a cohort of embryos further.     

Implantation: Embryo score to predict implantation after in-vitro fertilization: based on 957 single embryo transfers

The purpose of this study was to devise an embryo score to predictthe likelihood of successful implantation after in-vitro fertilization(IVF). Unlike most studies dealing with the influence of embryostage and morphology on pregnancy, our study was based on singlerather than multiple embryo transfers. A total of 957 singleembryo transfers were carried out. No delivery was obtainedafter any of the 99 transfers using 1-cell embryos or embryosobtained after delayed fertilization. In the remaining 858 transfers,the embryos had cleaved. Higher pregnancy rates were obtainedwith embryos displaying no irregular cells (11.7 versus 6.9%;P < 0.01) and embryos displaying no fragmentation (11.5 versus8.1%; P < 0.05). The 4-cell embryos implanted 2-fold moreoften than embryos with more or less cells (15.6 versus 7.4%;P < 0.01). Based on these observations, we devised a 4-pointembryo score in which embryos are assigned 1 point each if they(i) are cleaved, (ii) present no fragmentation, (iii) displayno irregularities, and (iv) have four cells. Both pregnancyrate and take home baby rate were significantly correlated withembryo score. Each point of this score corresponds to a 4% increasein pregnancy rate. Interestingly, pregnancy rate was significantlylower in women aged >38 years (8.2 versus 11.4%; P < 0.05),even though embryo quality was similar regardless of age. Singleembryo transfer allowed us to define a simple and useful embryoscore to choose the best embryo for transfer to optimize IVFand embryo transfer outcome. The use of this embryo score coulddecrease multiple pregnancies after multiple embryo transfers.     

Calculating the implantation potential of day 3 embryos in women younger than 38 years of age: a new model

For optimal embryo selection in IVF/intracytoplasmic sperm injection (ICSI), knowledge of the implantation potential is essential. This is a retrospective analysis of morphological characteristics and cleavage kinetics of day 3 embryos resulting in an objective assessment of the relative implantation potential of each distinct type of embryo. Therefore transferred embryos were sampled according to their documented implantation behaviour: all embryos without any implantation on the one hand and all those with 100% ongoing implantation on the other. There were 213 such embryos in the latter group of which only seven (3%) had >20% fragmentation and only one embryo (0.5%) showed multinucleation (an embryo containing >20% fragmentation). For this reason, only embryos with < or =20% fragmentation and without multinucleation were analysed. They were split up according to the amount of fragmentation and the number of blastomeres on day 2 and on day 3. For each type, the implanted fraction was calculated, i.e. the number certainly implanted divided by the sum of the number certainly implanted and the number certainly not implanted, thus describing its relative implantation potential. By extrapolation to the entire population it was possible to establish the implantation potential for each type of embryo. Optimal day 3 embryos were calculated to reach a mean of 47% ongoing implantation. By establishing the implantation potential for most embryos, this model also provides useful information about which embryos are worth freezing in a cost-effective cryopreservation policy.     

High outcome predictability after IVF using a combined score for zygote and embryo morphology and growth rate

BACKGROUND: A scoring system has been developed to determine preimplantation embryo quality, and used to select embryos for transfer into the uterus of patients. METHODS AND RESULTS: The system was used to study early embryo development and to test whether these scores alone can accurately predict IVF outcome. Following zygote and embryo scores through early development, the data showed that a top quality zygote does not necessarily indicate that the resulting embryo will be top quality after in-vitro culture. The embryo quality score can change dramatically when embryos are cultured to day 2 or 3 post-fertilization. Pregnancy rates and implantation rates were compared with the cumulative and separated zygote and embryo scores. Analysis of the predictability of scoring systems suggested that morphological scores alone are relatively unpredictive of IVF outcome. When weighted for in-vitro growth rate, scores were highly predictive, more so than the rate of development alone. CONCLUSIONS: These data suggested that a combination of in-vitro growth rate and morphological analysis both of zygotes and embryos was highly indicative of outcome after IVF. The results can be adopted to the single embryo transfer approach to IVF.     

Comparison of pulsatility indices on the day of oocyte retrieval and embryo transfer

Transvaginal ultrasonography with colour blood flow imagingand analysis of impedance to uterine arterial blood flow hasbeen used to provide an index of uterine receptivity for implantationafter IVF/embryo transfer. A mean uterine arterial pulsatilityindex (PI) >3.0 at the time of embryo transfer predicted35% of failures to become pregnant. Cryopreserving embryos innon-receptive cycles and transferring them in receptive cycleswould be expected to improve pregnancy rates. Earlier decisionsregarding embryo cryopreservation can be made if receptive cyclescan be predicted at the time of oocyte retrieval rather thanat embryo transfer. To assess differences in uterine arteryimpedance, PI were measured serially in 107 women on both theday of oocyte retrieval and the day of embryo transfer. MeanPI on the day of oocyte retrieval was 2.52 ± 0.59, andon the day of embryo transfer was 2.78 ± 0.45. No significantdifference was observed when PI determined on the day of oocyteretrieval were compared with PI on the day of embryo transfer.These data suggest that the PI measurement done on the day ofoocyte retrieval could substitute for the measurement done onthe day of embryo transfer. This would allow prediction of non-receptiveendometria earlier in the cycle. Further studies are neededto evaluate whether cryopreservation of embryos and transferwhen the uterus is more receptive will increase the implantationrates.     

Embryonic morphology and rate of implantation of human embryos following co-culture on bovine oviductal epithelial cells

A study was undertaken to evaluate embryonic development andestablish pregnancies with human embryos after in-vitro culturein two different systems. Treatment A consisted of culturingzygotes in serum-supplemented human tubal fluid culture medium(HTF). Treatment B consisted of culturing zygotes on a monolayerof bovine oviductal epithelial cells with HTF. At the time ofembryo replacement, embryos in treatment B had 4.11 blastomerespresent, which was greater (P < 0.05) than the 3.81 presentfor embryos in treatment A. In addition, the cellular fragmentationrate for treatment A embryos was 1.10, which was greater (P< 0.05) than the fragmentation rate of 0.38 for embryos withintreatment B. The incidence of ongoing pregnancy was higher afterreplacement of co-cultured embryos (treatment B) (43%) thanreplacement of conventionally cultured embryos (treatment A)(29%). The implantation rate per embryo increased (P < 0.05)from 11.5 to 18.4% after co-culture. In treatment B the proportionof ‘spare’ embryos developing to expanded blastocystswas 58.5%, which was greater (P < 0.05) than the blastocystdevelopment rate of 29.3% observed for embryos within treatmentA.     

Enhancement of embryo developmental potential by a single administration of GnRH agonist at the time of implantation

BACKGROUND: Several reports have shown that inadvertent administration of a GnRH agonist in the luteal phase does not compromise pregnancy. Moreover, some studies suggested that, unexpectedly, the embryo developmental potential is improved in these conditions. This prospective controlled study was designed to test this hypothesis. METHODS: In an oocyte donation programme, oocytes from each donor (n = 138) were shared by two recipients, one of whom was given a single dose of a GnRH agonist (0.1 mg triptorelin) 6 days after ICSI, and the other received placebo at the same time. RESULTS: Oocyte recipients treated with GnRH agonist 6 days after ICSI had higher implantation (36.9 versus 25.1%), twin pregnancy (16.7 versus 3.6%), twin delivery (13.8 versus 2.2%) and birth (31.1 versus 21.5%) rates and similar miscarriage and abortion rates as compared with the placebo group. CONCLUSIONS: GnRH agonist administration at the time of implantation enhances embryo developmental potential, probably by a direct effect on the embryo.     

The cumulative embryo score: a predictive embryo scoring technique to select the optimal number of embryos to transfer in an in-vitro fertilization and embryo transfer programme.

In order to achieve a clinical pregnancy rate higher than that achieved following initial adoption of in-vitro fertilization embryo transfers, more than one embryo is transferred. This has led to a substantial increase in unwanted multiple pregnancy rates with IVF as compared with natural conception. What is therefore required is a simple, clinically useful embryo scoring system, to reflect embryo developmental potential, which will enable the selection of the optimal number of embryos to transfer in order to achieve the maximum pregnancy rate with a low incidence of high order multiple pregnancies. We believe that the Cumulative Embryo Score (CES) achieves these aims. On the day of embryo transfer the grade of each embryo transferred was multiplied by the number of blastomeres to produce a score for each embryo, and summation of the scores obtained for all the embryos transferred gave the CES. The grouped pregnancy rates obtained rose as the CES increased to maximum of 42. A continued increase in the CES above 42 did not result in any further rise in the pregnancy rate. However, an analysis of all our IVF pregnancies showed that the multiple pregnancy rate continued to rise above a CES of 42. By restricting the CES per embryo transfer to 42, 78% of triplet pregnancies and 100% of the quadruplet IVF pregnancies could have been predicted and potentially avoided.     

The probability of pregnancy after embryo transfer is affected by the age of the patient, cause of infertility, number of embryos transferred and the average morphology score, as revealed by multiple logistic regression analysis

Because the process of conception is affected by many variables,a multiple logistic regression analysis was performed to assess(i) the impact and relative weight of both patient and embryovariables and (ii) their possible effects on the probabilityof a vital pregnancy after embryo transfer. A statistical modelwas constructed predicting the probability of pregnancy afterembryo transfer. The variables that contributed significantlyto the predictive value of the model were the age of the patient,the cause of infertility, the number of embryos transferredand the average morphology score of the transferred embryos.Embryo variables appeared to have a significant but modest valuein predicting the probability of pregnancy after embryo transfer.Other variables, such as the thickness of the endometrium, werefound to have no prognostic value. Moreover, we found that theireffect could be explained by the variables already includedin the model.     

The implantation of every embryo facilitates the chances of the remaining embryos to implant in an IVF programme: a mathematical model to predict pregnancy and multiple pregnancy rates

BACKGROUND: We aimed to assess the validity of a theoretical mathematical model to predict the pregnancy rate and the multiple pregnancy rate in IVF/oocyte donation programmes on the basis of the implantation rate and the number of transferred embryos. METHODS: A total of 1835 embryo transfers corresponding to three different programmes in two centres with different implantation rates were analysed. Pregnancy and multiple pregnancy rates observed in the aforementioned programmes were compared with those obtained following different mathematical models. Four models were tested: binomial model, ground model, maternal variability model and collaborative model. The goodness of fit was performed by means of the maximum likelihood fit method. RESULTS: The binomial model could not predict the pregnancy rate, and especially the multiple pregnancy rate. The multiple pregnancy rate predicted following the binomial model was much lower than observed, up to 40-fold reduced. Ground model and maternal variability model adjusted to the data with more precision, but were still not accurate. Finally, the collaborative model reproduced with very great accuracy both pregnancy rate and the multiple pregnancy rate. A collaborative parameter of 22% was found, implying that the implantation probability of each embryo is increased by 22% for every embryo previously implanted. CONCLUSIONS: Embryonic implantation does not follow a binomial law, showing that the implantation is not independent from the number of embryos implanted. The best fit to the data is obtained following a collaborative model by which the implantation of one embryo is facilitated by the implantation of other embryo(s). The mathematical formula of the collaborative model predicts very accurately the pregnancy rate and the multiple pregnancy rate in IVF/oocyte donation programmes, based on the implantation rate of this specific programme and the number of embryos transferred up to five embryos. We recommend using the aforementioned formula to quantify the pregnancy rate and the risk of multiple pregnancy in the counselling of the infertile couple at embryo transfer. Such a formula is freely available at www.ifca.unican.es/matorras/mathpreg/.     

A prospective randomized study comparing the outcome of in-vitro fertilization and embryo transfer following culture of human embryos individually or in groups before embryo transfer on day 2.

A prospective randomized trial of in-vitro fertilization and embryo transfer was undertaken to investigate the reported beneficial effects of culturing preimplantation human embryos in groups, rather than individually. A total of 159 treatment cycles, in which the women were matched for age, basal gonadotrophin concentrations and number of previous attempts, were included in the study. Of these, 78 cycles were randomized to the 'individual culture' group, and 81 cycles were randomized to the 'group culture' group. The groups did not differ in terms of the median number of oocytes or embryos obtained per cycle. There was no statistically significant difference between the two groups in terms of treatment outcome, as assessed by pregnancies or clinical pregnancies.     

Limited value of morphological assessment at days 1 and 2 to predict blastocyst development potential: a prospective study based on 4042 embryos

BACKGROUND: Non-invasive and routine developmental markers are available to select the most viable embryo; however their respective values in terms of blastocyst development potential remain difficult to distinguish. METHODS: During this prospective study, the sequential growth of 4042 embryos individually cultured from day 1 to day 5/6 was recorded. Pronuclear morphology on day 1, and early cleavage, cell number and fragmentation rate on day 2 were evaluated for each zygote. Additionally, blastocyst transfers were analysed with regard to their implantation ability and early embryo development parameters. RESULTS: Once adjusted to each other, each of the four parameters remained related to blastocyst development. Early cleavage and cell number on day 2 were the most powerful parameters to predict the development of a good morphology blastocyst at day 5. Moreover, whereas transfers of a good morphology blastocyst were associated with high implantation and live birth rates, parameters of early development were not helpful in predicting their implantation ability. CONCLUSIONS: The combination of all four parameters allowed the prediction of blastocyst development with an area under the receiver operating characteristics curve of 0.688, which represents a fairly low prediction of embryo viability. Such results indicate that it is necessary to search for additional criteria, including the ability of the blastocyst to develop.     

Effect of dehydroepiandrosterone on oocyte and embryo yields, embryo grade and cell number in IVF

BACKGROUND: The aim of this study was to investigate the effect of treatment with dehydroepiandrosterone (DHEA) on fertility outcomes among women with diminished ovarian reserve. MATERIALS AND METHODS: This is a case-control study in an academically affiliated private infertility centre. Twenty-five women with significantly diminished ovarian reserve had one IVF cycle before and after DHEA treatment, with otherwise identical hormonal stimulation. Women received 75 mg of DHEA daily (25 mg three times daily) for an average of 17.6 +/- 2.13 weeks. We performed a comparison of IVF outcome parameters, before and after DHEA treatment, including peak estradiol (E(2)) levels, oocyte and embryo numbers, oocyte and embryo quality and embryo transfer statistics. RESULTS: Paired analysis of IVF cycle outcomes in 25 patients, who underwent cycles both before and after DHEA supplementation, demonstrated significant increases in fertilized oocytes (P < 0.001), normal day 3 embryos (P = 0.001), embryos transferred (P = 0.005) and average embryo scores per oocyte (P < 0.001) after DHEA treatment. CONCLUSION: This study confirms the previously reported beneficial effects of DHEA supplementation on ovarian function in women with diminished ovarian reserve.     

Twin pregnancy following embryo transfer on day 7 of the luteal phase in an oocyte donation programme

We report a case of a 42 year old female patient with hypergonadotrophichypogonadism requiring oocyte donation. Spontaneous ovulationoccurred during a hormonal replacement treatment cycle and threeembryos were transferred 7 days after documented ovulation.This resulted in a viable twin pregnancy. The twins were geneticallydistinct from the mother. To the best of our knowledge thisis the first reported case of a successful transfer of embryoson day 7 of the luteal phase leading to a viable pregnancy inan oocyte donation programme.     

A quantitative analysis of the impact of cryopreservation on the implantation potential of human early cleavage stage embryos

The impact of cryopreservation on the implantation potential of early cleavage stage (day 2) embryos was assessed by analysing the outcome from > 5000 thawed embryos in relation to the outcome from a similar number of fresh embryos. Analysis of procedures in which all transferred embryos fulfilled equivalent defined criteria revealed no significant difference in the implantation rates (fetal hearts/100 embryos transferred) of fresh 4-cell embryos (16.6%) and fully intact thawed 4-cell embryos (16.9%). Although 2-cell embryos implanted at significantly lower rates, there was again no significant difference between fresh (6.5%) and fully intact thawed (7.2%) embryos. Similar analysis of all embryos (irrespective of cell number on day 2) demonstrated that the implantation potential of partially intact thawed embryos was related to the extent of blastomere loss with the implantation rate of embryos with 50% cell survival (5.4%) being approximately half the rate of fully intact embryos (11.3%). Combining the values obtained from 'pure' data for the implantation rates of embryos with defined levels of survival with their relative prevalence in the total population of thawed embryos gave a predicted number of implantations (441) which was similar to the observed outcome (463). This number was approximately 30% less than the number expected had the same embryos been transferred fresh (635). The results suggest that intact thawed embryos have the same implantation potential as equivalent fresh embryos and that the impact of cryopreservation is limited to blastomere loss which is directly related to loss of implantation potential. The observed frequency of blastomere loss results in a reduction of approximately 30% in the implantation potential of a population of embryos following cryopreservation.     

The influence of the depth of embryo replacement into the uterine cavity on implantation rates after IVF: a controlled, ultrasound-guided study

BACKGROUND: Traditionally, embryo transfer after IVF has been performed blindly and placing the embryos approximately 1 cm below the fundal endometrial surface. However, it has been suggested that transferring embryos rather lower in the uterine cavity or high in the uterus may improve implantation rates. Nevertheless, there has not yet been a controlled trial to prove this theory. This prospective randomized study investigates the influence of the depth of embryo replacement on the implantation rate after embryo transfer carried out under transabdominal ultrasound guidance. METHODS: A total of 180 consecutive patients undergoing ultrasound-guided embryo transfer were randomized to three study groups according to the distance between the tip of the catheter and the uterine fundus at the moment of the embryo deposition in the lumen of the endometrial cavity: group 1: 10 +/- 1.5 mm; group 2: 15 +/- 1.5 mm; group 3: 20 +/- 1.5 mm. RESULTS: There was equal distribution between all three study groups regarding the main demographic and baseline characteristics of the patients, ovarian response, oocyte retrieval and IVF outcome, as well as the characteristics of embryo transfer and luteal phase support. The position of the catheter tip in relation to the fundal endometrial surface in groups 1 (10.2 +/- 0.9 mm), 2 (14.6 +/- 0.7 mm) and 3 (19.3 +/- 0.8 mm) was significantly different. Implantation rate was significantly higher (P < 0.05) in groups 2 (31.3%) and 3 (33.3%) compared with group 1 (20.6%). CONCLUSIONS: The depth of the embryo replacement into the uterine cavity may influence implantation rates, and thus it should be considered as an additional procedure among factors recently proposed as associated with successful embryo transfer after IVF.     

In-vitro development and implantation of human embryos following culture on fetal bovine uterine fibroblast cells

Human zygotes resulting from IVF were placed in two differentculture systems to evaluate in-vitro development and to establishpregnancies in patients following embryo replacement. TreatmentA (control) consisted of culturing zygotes in a modified Earle'sBalanced Salt solution while treatment B consisted of culturingzygotes on a monolayer of fetal bovine uterine fibroblasts inthis same culture medium. At the time of embryo replacement,embryos within treatments A and B had 3.7 and 4.3 blastomerespresent, respectively. After 24 h in culture, the cellular fragmentationrate for treatment A embryos was 0.85 which was greater (P <0.05)than the fragmentation rate of 0.44) for embryos within treatmentB. The incidence of implantation for patients whose embryoswere given treatment A was 17.0% which was lower (P <0.05)than 35% for those given treatment B. Implantation rates increasedwith time in culture (43%) for treatment B embryos. Cultureby treatment B of three pronucleate zygotes resulted in 7/9and 4/9 reachIng the blastocyst and expanded blastocyst stages,respectively, whereas only 1/26 three-pronucleate zygotes culturedusing treatment A reached either of these stages.     

Morphologic parameters of early cleavage-stage embryos that correlate with fetal development and delivery: prospective and applied data for increased pregnancy rates

BACKGROUND: Many different embryo selection criteria have been used in assisted reproductive technologies (ART), but there are no published prospective studies to ascertain their usefulness in predicting implantation. METHODS: In a prospective trial, 20 early scoring parameters previously reported to influence clinical outcome were collected, but embryos were selected for transfer by current laboratory protocols; day 1 pronuclear (PN) (Z) score combined with day 3 or 5 morphology. Data points for each oocyte/embryo were scored independently and tracked individually. Data were analysed retrospectively for parameters most likely to result in a positive pregnancy test, fetal heartbeat (FHB) and delivery. RESULTS: Results indicated that day 1 PN morphology and nucleolar precursor body (NPB) ratio, day 2 cell number, blastomere symmetry and nucleation and the ability to cleave from day 2 to day 3 were the six most significant factors in fetal development. This outcome was then applied prospectively over 8 months. The implantation rate (IR) and clinical pregnancy rate (CPR) increased in each age group, and the number of embryos used decreased. CONCLUSION: In conclusion, early parameters that include PN morphology, number and ratio of NPBs per nucleus and the day 2 morphology of cleaving embryos are stronger positive predictors of implantation than day 3 morphology or the ability to achieve the blastocyst stage of development. Parameters that were most consistently correlated with no delivery were lack of PN symmetry, day 2 multinucleation and uneven cell size. Day 3 and day 5 parameters were not significant compared with the combination of early parameters.     

Influence of early ICSI-derived embryo sHLA-G expression on pregnancy and implantation rates: a prospective study

BACKGROUND: We have previously reported the retrospective observation that when at least one embryo, transferred on day 3, expressed sHLA-G above the geometric mean (sHLA-G+) 46 h post-ICSI, there was a marked improvement in both pregnancy (PR) and implantation (IR) rates. METHODS: The media surrounding individual embryos derived from ICSI performed on oocytes from 482 women < or =43 years of age were tested for sHLA-G expression by specific ELISA. RESULTS: We report here prospective results showing improved IVF results following the transfer of 'good quality' embryos (7-9 cells with <20% fragmentation) by preferentially including at least one sHLA-G+ embryos. PR and IR for women < or =38 years were 63% and 32% when one transferred embryo was sHLA-G+, and 69% and 36% when at least two embryos were sHLA-G+. When none of the embryos transferred was sHLA-G+, PR and IR were 25% and 13%, respectively. Comparable PR and IR for women 39-43 years were 29% and 11% when none of the transferred embryos were sHLA-G+; 38% and 15% when at least one sHLA-G+ embryo was transferred; and 61% and 26% when at least two 2 sHLA-G+ embryos were transferred. The data were stratified by patient age. CONCLUSIONS: PR and IR increased with the addition of each sHLA-G+ embryo, regardless of age. While there are significant barriers to routine embryo sHLA-G testing, we believe that if implemented, this would provide a mechanism for optimizing IVF PR while minimizing the risk of multiple pregnancies.