Fresh Single Blastocyst Transfer Research Articles

P-267 The morula stage. Is it time to repair?

Abstract Study question Are there statistically significant differences in embryo’s fate when exclusion or extrusion of blastomeres is detected along development? Summary answer According to our results, exclusion or extrusion of blastomeres affects the embryo’s subsequent viability, suggesting that different biological processes are involved in its appearance. What is known already The morula stage is a clear example of embryo plasticity, being a critical step towards blastocyst development. One morphokinetic parameter observed at this stage is the exclusion (before compaction) and extrusion (during or after compaction) of blastomeres. Exclusion and extrusion seem to be related to embryo self-correction phenomena and they are considered negative criteria due to potential associations with tight junction failures, gene expression, aneuploidies, or a high degree of mosaicism. However, the moment in which those phenomena are detected, can have different origins and though different consequences in embryo development. Study design, size, duration A total of 668 fertilized embryos and cultured to the blastocyst stage were included in the study. Embryo cohorts correspond to 158 consecutive patients that underwent an IVF treatment with fresh single blastocyst transfer and all their cohorts, between June 2017 and September 2022. Data recovered during culture in time-lapse incubator regarding the extrusion or exclusion of cells and the final fate of the transferred and the cohort embryos were retrospectively analysed. Participants/materials, setting, methods Embryos were cultured in single culture medium (CSCC®, Irvine Scientific) in a time-lapse incubator (MIRI-TL®, ESCO Medical). Embryos were evaluated for the time of exclusion/extrusion, number and volume of excluded/extruded cells and their final fate (transferred and the result, vitrified, discarded). For those transferred, Beta-hCG was performed 14 days after transfer and if positive clinical pregnancies were confirmed 3 weeks later. Data were analysed using IBM SPSS Statistics v25.0, with p < 0.05 indicating statistical significance. Main results and the role of chance Of the 668 analysed embryos, 340 were deemed “useful”: 225 were transferred (158 fresh, 67 cryotransferred after fresh negative pregnancy test), and 115 remain still vitrified. The rest, 328, were considered “non-useful”: 84 discarded and 244 blocked. 37% of the embryos presented total compaction and 63% partial, being 70.1% exclusion, 9.7% extrusion and 20.2% both phenomena. Exclusion/extrusion was significantly higher (p < 0.05) in non-useful embryos compared to the useful ones. In the distribution with regards to the final fate, significant differences were found (p < 0.05) being 78% exclusion, 8.8% extrusion and 13.3% both for useful, and 53.8% exclusion, 5.8% extrusion and 40.4% both for non-useful. There were statistically significant differences (p < 0.05) in the volume and number of cells excluded/extruded and the fate, being higher in those that resulted non-useful. ROC analysis showed that the volume occupied by excluded cells influences the embryo’s fate (AUC=0.738). Regarding transferred embryos, those that presented the phenomenon and resulted in a positive beta-hCGs, 95.8% was exclusion, none of them extruded cells and 4.2% both. For the negatives, 71% of exclusion, 11.4% of extrusion and 17.1% both, resulting in non-significant differences (p = 0.055). No significative differences were found either for the ones that resulted in a clinical pregnancy. Limitations, reasons for caution Although no statistical differences were found according to the moment of exclusion of blastomeres, before or after compaction, and the pregnancies, there is a clear trend in the sooner it happens the more embryo viability. And increase in the sample size might be helpful to confirm it. Wider implications of the findings The establishment of new parameters can improve embryo selection to help embryologists discriminating between embryos that appear to be of similar quality. Trial registration number not applicable

P-429 Measuring serum progesterone levels on the day of a fresh blastocyst transfer is debatable as there is no evidence for correlation with ongoing pregnancy results

Abstract Study question Does serum progesterone (P4) level on the day of a fresh blastocyst transfer relate to ongoing pregnancy rate (OPR)? Summary answer OPR after a fresh single blastocyst transfer seems not to be associated with serum P4 level on the day of transfer. What is known already Several studies have suggested an optimal serum P4 threshold for embryo transfers in frozen embryo transfer cycles. However, for fresh embryo transfers, data are scarce and conflicting. Study design, size, duration A retrospective single-center cohort study was performed on 598 complete data cycles, retained out of 631 consecutive fresh single blastocyst transfer cycles. Data were collected from patients undergoing a fresh IVF/ICSI cycle with autologous oocytes at a tertiary fertility center between June 2022 and August 2023. Participants/materials, setting, methods A total of 482 unique patients underwent one or more single fresh blastocyst transfers using micronized vaginal progesterone (MVP) 800mg BID for luteal phase support starting day after oocyte retrieval. Serum P4 levels were determined on day of transfer. The primary endpoint was OPR, positive hCG-test and early pregnancy loss (EPL) were secondary endpoints. Unadjusted and adjusted generalized estimating equations (GEE) assessed P4 level association with the endpoints, using an exchangeable working correlation matrix. Main results and the role of chance No association was identified between P4 levels on day of transfer and OPR after accounting for maternal age, blastocyst quality, P4 and estradiol level at last ultrasound, BMI and endometrial thickness. Data were grouped according to 10/50/90 and 25/50/75 percentiles, resulting in groups < = or > 27ng/ml and < = or > 40ng/ml, with omission of 90th and 75th percentile groups due to right-skewed distribution. With serum P4 levels higher than 40ng/ml, the probability of a positive hCG-test significantly increased (OR 1.79, CI 1.11-2.91; p = 0.018). No significant difference was observed in patients with serum P4 < = or > 27ng/ml (OR 1.23, CI 0.66-2.30; p = 0.506). Regarding OPR, no significant differences were observed when comparing patients with serum P4 < = or > 27/ng/ml or < = or > 40ng/ml (OR 0.88, CI 0.42-18.85; p = 0.736 and OR 1.41, CI 0.83-2.37; p = 0.203, respectively). Moreover, EPL did not significantly differ between serum P4 level groups (OR 1.93, CI 0.61-6.13; p = 0.265 and OR 1.2, CI 0.51-2.84; p = 0.674). Age (p < 0.001) and embryo quality (p < 0.001) are significantly related with OPR. Additionally, late follicular progesterone levels and OPR are significantly associated (OR 2.39, CI 1.16-4.95 in patients with P4 < = or > 27/ng/ml and OR 2.21, CI 1.07-4.55 in patients with < =40ng/ml and >40ng/ml). Limitations, reasons for caution Limitations include the retrospective design and the lack of live birth outcome data. Progesterone levels exceeding 60 ng/ml were not further analyzed to their precise value but grouped as 60 plus which did not allow to identify potential detrimental effects of very high P4 levels on treatment outcome. Wider implications of the findings Our data suggest that measuring P4 on the day of a single blastocyst transfer with MVP luteal phase support may not be indicative of OPR or the risk of EPL. This raises questions regarding the necessity for routine P4 measurements as well as the development of rescue strategies. Trial registration number ONZ-2023-0628

P-418 What is the optimal midluteal phase circulating progesterone level during a fresh IVF cycle? The answer differs from what one expects in a natural cycle

Abstract Study question Do midluteal phase circulating progesterone (P4) levels relate to the fresh embryo transfer clinical outcome and is rescue P4 useful in such cases? Summary answer Live birth rate (LBR) was significantly lower when P4 levels were below 20ng/ml and did not seem to benefit from rescue intramuscular P4. What is known already Preceding literature on the predictive value of midluteal P4 for LBR has shown conflicting results and frequently included small sample sets and heterogeneous ovarian stimulation protocols. The findings reported ranged from the lack of an association between P4 serum levels and clinical outcome to worse success rates seen either in the groups with the highest or the lowest P4 in midluteal phase. Furthermore, while rescue P4 has been empirically proposed, it has lacked formal assessment thus far. Study design, size, duration In total, 652 patients who underwent a fresh single blastocyst transfer in an IVF cycle in our center between 2014 and 2021 were included in this retrospective cohort study. All were GnRH-antagonist cycles using hCG trigger and luteal support with micronized vaginal progesterone 200mg twice daily. Rescue intramuscular progesterone was systematically administered whenever low midluteal P4 (below 1 standard deviation of the center’s mean) levels were detected. Participants/materials, setting, methods The cycles were subdivided into three groups according to the midluteal P4 levels: <10ng/ml, 10-20ng/ml and >20ng/ml. The primary outcome assessed was LBR, with secondary outcomes including clinical pregnancy (CPR) and pregnancy loss rates. Maternal age and body mass index (BMI), year of treatment, ovarian response, endometrial thickness, cause of infertility and embryo quality were controlled for using multivariable logistic regression. Main results and the role of chance The mean age ± standard deviation of patients was 36.8±3.8 years, while mean weight and BMI were 63.2±11.5kg and 23.3±3.9kg/m2, respectively. LBR in the group with P4>20ng/ml (46.5%) was significantly higher than in the groups with low and intermediate P4 serum levels (23.1% and 28.1%, respectively, p < 0.001). The same was true for CPR (54.5%, 30.8% and 37.9%, respectively, p < 0.001). Conversely, the rate of pregnancy loss in the group with P4>20ng/ml (23.8%) was significantly lower than in the groups with low and intermediate P4 levels (42.6% and 37.5%, respectively, p = 0.018). The multivariable logistic regression confirmed that, after controlling for the confounding variables described above, P4>20ng/ml remained significantly associated with a higher LBR (OR: 2.285; 95% CI: 1.506-3.469) and a lower pregnancy loss rate (OR: 0.488; 95% CI: 0.273-0.873), irrespective of the use of rescue IM P4. Finally, a multivariable linear regression analysis of the patients baseline characteristics suggested that the only parameter predictive of midluteal P4 levels was the female patients’ weight, with an inverse relationship (adjusted regression coefficient: -0,012; 95% CI: -0,016/-0,009). Limitations, reasons for caution As the pituitary suppression, ovulation trigger and luteal support protocols used in the cycles included in the study were homogeneous (in order to maximize the internal validity of the results), this limits the extrapolibility of the results to other stimulation protocols. Furthermore, we caution that this is a retrospective study. Wider implications of the findings The usefulness of both midluteal P4 serum measurements and rescue P4 should continue to be assessed. The reasons behind the need for higher levels of P4 in a fresh cycle, when compared to natural cycles, must also be investigated. Luteal support may require personalization according to female body weight. Trial registration number Not Applicable

Culture media affect sex after IVF treatment-a detailed analysis of explanatory variables.

The purpose of this study was to provide a detailed analysis of clinical and laboratory factors associated with skewed secondary sex ratio (SSR) after ART. Retrospective cohort study of embryos resulting in live births, from frozen and fresh single blastocyst transfers. Embryos were cultured in either G-TL (n = 686) or Sage media (n = 685). Data was analyzed using a multivariate logistic regression model and a mixed model analysis. Significantly more male singletons were born after culture in Sage media compared to G-TL media (odds ratio (OR) 1.34, 95% CI (1.05, 1.70), P = 0.02). Inner cell mass grade B vs A (OR 1.36 95% CI (1.05, 1.76), P = 0.02) and one previous embryo transfer (OR 1.49, 95% CI (1.03, 2.16), P = 0.03) were associated with a significantly higher probability of male child at birth. Factors associated with a reduced probability of male child were expansion grade 3 vs 5 (OR 0.66, 95% CI (10.45, 0.96), P = 0.03) and trophectoderm grade B vs A (OR 0.57, 95% CI (0.44, 0.74), P = 0.00). Male embryos developed significantly faster in Sage media compared to G-TL media for the stages of blastocyst (- 1.12h, 95% CI (- 2.12, - 0.12)), expanded blastocyst (- 1.35h, 95% CI (- 2.34, - 0.35)), and hatched blastocyst (- 1.75h, 95% CI (- 2.99, - 0.52)). More male children were born after culture in Sage media compared to G-TL media. Male embryo development was affected by culture media. Our observations suggest that culture media impact male embryo quality selectively, thus potentially favoring the selection of male embryos.

Retrospective Analysis of Fresh Single Blastocyst Transfer versus Two Cleavage-Stage Fresh Day-3 Embryo Transfer with High-Quality Embryos during Gonadotropin-Releasing Hormone Antagonist Cycles in High Responders

Retrospective Analysis of Fresh Single Blastocyst Transfer versus Two Cleavage-Stage Fresh Day-3 Embryo Transfer with High-Quality Embryos during Gonadotropin-Releasing Hormone Antagonist Cycles in High Responders

P-183 Blastocyst speed versus blastocyst look: Which is the better predictor of clinical pregnancy and live birth following time-lapse culture and single blastocyst transfer?

Abstract Study question To compare predictive value for pregnancy and live birth of morphological versus morphokinetic assessment of blastocysts after time-lapse culture and single blastocyst transfer. Summary answer Blastocyst morphokinetic assessment was not superior in predicting pregnancy and live birth compared to blastocyst morphology, but provides additional information, particularly for morphologically poorer-quality blastocysts. What is known already Blastocyst culture with time-lapse technology enables evaluation of both morphokinetic developmental speed and classical morphology including Gardner scoring of the blastocyst. One approach to assess the developmental speed of blastocysts is to use the morphokinetic classification proposed by Campbell, Fishel, et al., based on time to start of blastulation (tSB) and the duration of forming the blastocyst (dB). However, beyond the advantages of undisturbed embryo culture, the value of the kinetic data from time-lapse is debated. Study design, size, duration EDCOS (Embryo Developmental profiles from Controlled Ovarian Stimulation cycles using follitropin alfa) is a multicentre, prospective cohort study of patients undergoing IVF/ICSI whose embryos were cultured in time-lapse incubator devices in 10 ART centres throughout Denmark and Sweden. Patients undergoing IVF/ICSI (including donor oocyte cycles) who had ovarian stimulation with follitropin alfa (Bemfola®) and had zygotes and embryos available for monitoring in the EmbryoScope™ time-lapse incubator device (Vitrolife) were invited to join this study. Participants/materials, setting, methods Morphological and morphokinetic prognostic classifications for single blastocyst transfers (SET) were determined for three study subpopulations: fresh autologous SET (311 women), frozen autologous SET (246 women; 345 transfers) and frozen donor SET (38 women; 59 transfers). All blastocysts were graded morphologically in five grades from Amorph (best) to Emorph (worst) based on their Gardner score and morphokinetically in three grades from Akin (best) to Ckin (worst) based on tSB and dB. Main results and the role of chance Overall ongoing pregnancy and live birth rates (OPR/LBR) for morphokinetic classifications Akin, Bkin and Ckin were 36.1%, 30.0% and 16.3% (P = 0.021) and 30.4%, 21.8% and 9.1% (P = 0.000), respectively. OPR and LBR for morphological classifications Amorph, Bmorph, Cmorph, Dmorph and Emorph were 41.9%, 37.8%, 30.8%, 19.0% and 15.6% (P = 0.000) and 36.6%, 29.1%, 15.6%, 16.5% and 8.3% (P = 0.002), respectively. For Dmorph blastocysts, OPR and LBR for morphokinetic classifications Akin, Bkin and Ckin were 50%, 21.4% and 7.1% (P = 0.009) and 33.3%, 10.8% and 0% (P = 0.003), respectively. Receiver operating characteristic curve analyses achieved areas under the curve for fresh autologous SET of 55.7%, 58.9% and 67.2% for the morphokinetic, morphological and combined classifications, respectively; and 53.4%, 64.0% and 65.6%, respectively, for frozen autologous SET. Limitations, reasons for caution This was an observational study with no control group, conducted under usual clinical practice. Data were collected prospectively, although clinics could deselect and rank blastocysts according to their own procedures. However, the outcome of subsequent frozen blastocyst transfer cycles was also analysed. Wider implications of the findings Selection of a blastocyst for transfer based on morphokinetic assessment at the blastocyst stage was not superior to classical blastocyst morphological assessment after time-lapse culture but is a viable option. Combining morphokinetic and morphological evaluation provides additional supporting information to guide in blastocyst selection, especially for morphologically poorer-quality blastocysts. Trial registration number Not applicable

P-208 Culture media affect gender after IVF treatment: A detailed analysis of explanatory variables

Abstract Study question Does embryo culture media affect gender at birth and why? Summary answer More male children were born after culture in the Sage 1-Step media compared to the G-TL media. What is known already ART increases the proportion of male children at birth. Laboratory techniques and culture conditions is known to impact secondary sex ratio (SSR). Physiological development differs in male and female embryos, leading to different metabolic requirements at the preimplantation stage. The composition of commercial culture medias varies and thus, the different medias may have different impact on embryo development and quality according to gender. This, in turn, may influence SSR, as embryos are selected based on morphological scoring systems and developmental speed. Study design, size, duration The study was designed as a retrospective registry-based study with all data collected at a single clinic. All embryos resulting in live birth from frozen and fresh single blastocyst transfers, in the period from 1. January 2017 to 31. December 2020 were included. Donor embryos and embryos cultured in more than one culture media were excluded. A total of 1371 SET embryos were included. Participants/materials, setting, methods Embryos were cultured in either the G-TL media, Vitrolife (n = 686) or the Sage 1-Step media, Origio (n = 685). All embryos were monitored for 5-6 days in a time-lapse incubator, Vitrolife, before single blastocyst transfer. Multivariate logistic analysis of cycle and embryo characteristics was performed to identify all factors associated to sex. The association between culture media and embryo morphokinetic according to sex was evaluated using a mixed model analysis. Main results and the role of chance Significantly more male singletons were born after culture in 1-Step media compared to G-TL media (risk ratio (RR) 1,1 95% CI [1,0, 1,3], P = 0,01). The female/male ratio was 42,3/57,7% in 1-Step media and 48,5/51,5% in G-TL media. The multivariate regression analysis displayed a higher chance of a male child with higher expansion grade (grade 5) (RR, 1,2 95% CI [1,0, 1,4] P = 0,04), lower inner cell mass grade (grade B) (RR 1,13 95% CI [1,0, 1,3] P = 0,02) and second embryo transfer (RR 1,2 95% CI [1,0, 1,3] P = 0,03). Trophectoderm (TE) grade B reduced the probability of male child compared with TE grade A (RR 0,8 95% CI [0,8, 0,9] P > 0,05). Male embryos developed significantly faster in the 1-Step media compared to the G-TL media for the stages of; blastocyst (tB) (-1,1 hours 95% CI [-2,1, -0,1]), expanded blastocyst (tEB) (-1,3 hours 95% CI [-2,3, -0,3]) and hatched blastocyst (tH) (-1,7 hours 95% CI [-3,0, -0,5]). Timing of development were the same for female embryos in the G-TL media compared to the 1-Step media. There was no significant difference in timing of development between female and male embryos in identical culture media. Limitations, reasons for caution This study was a retrospective study with data collection from only a single clinic, and as such in risk of confounding. Apart from culture media, culture conditions were similar during the two time periods. Paternal factors and type of infertility was not included. Wider implications of the findings Our observations suggest that culture media impact male embryo quality selectively, thus favoring selection of male embryos. As the impact appears to vary between different culture media, and has a measurable impact on gender after birth, the influence of culture media on embryo quality deserves more attention. Trial registration number not applicable

P-263 Increased live birth rate, blastocyst formation and quality when embryos were cultured in EmbryoScope time-lapse incubators compared to MINC™ benchtop incubators

Abstract Study question Does embryo culture using the EmbryoScope or EmbryoScope+ time-lapse incubators affect blastocyst development and birth rate compared to MINC™ benchtop incubators? Summary answer Culture in the EmbryoScope or EmbryoScope+ resulted in higher blastocyst quality and utilisation rates, and birth rates from fresh blastocyst transfers was increased. What is known already Time-lapse incubators enable continuous monitoring of embryos so that morphological changes can be observed, and embryo selection software applied to select the best embryo for transfer. However, there has been considerable debate over the benefits of such systems and a review of 8 randomized controlled trials (Armstrong et al., 2019; Cochrane Database Syst Rev (5)) was inconclusive. Interpretation and comparison of results are complicated by differences among imaging systems and variations in culture protocols between clinics. EmbryoScope time-lapse incubators may also have better temperature and pH stability than benchtop incubators, improving embryo development. Study design, size, duration Retrospective data from 1189 cycles in the EmbryoScope or EmbryoScope+ and 1381 MINC cycles conducted concurrently in the same laboratory over 18 months. All embryos from each patient cycle were cultured in one incubator type. All patients from a treating clinician were allocated to one incubator type. Participants/materials, setting, methods All IVF/ICSI cycles from a single clinic. Cycles with vitrified eggs or embryos were excluded. Embryos were cultured in Vitrolife G-TL media under 5% O2, media was refreshed on Day 5. Embryos were scored using the Gardner grading system. For embryos cultured in the Embryoscope, selection of embryos for transfer was based on a combination of Gardner grading and the KIDScore D5 v2 algorithm. Main results and the role of chance There was an increase in Day 5 top quality blastocysts (AA) from embryos in the Embryoscope compared to the MINC (15.3% vs.9.7%, p < 0.0001), and Day 5 good quality blastocysts (≥BB, 24.4% vs.16.9%, p < 0.0001). Overall, the utilisation rate was significantly higher from embryos in the Embryoscope (51.3% vs.46.0%, p < 0.0001). From fresh single blastocyst transfers, there was a significant increase in detection of fetal heart by ultrasound (34.7% vs 28.0% p < 0.01) and live birth rate (30.9% vs 24.6%, p<0.01) from embryos cultured in the Embryoscope (n = 972) compared to the MINC (n = 633). Interestingly, pronuclei were not observed during fertilisation assessment for 84 embryos that subsequently formed blastocysts cultured in the MINC, compared to only 4 embryos in the Embryoscope, suggesting that continuous monitoring increases accuracy in determining fertilisation. Limitations, reasons for caution Assessment using the EmbryoViewer compared to an inverted microscope may result in discrepancy in blastocyst grades. The use of KIDscore combined with Gardner grading for embryo selection in the Embryoscope but not the MINC may influence transfer outcomes. As data was collected retrospectively, patients were not randomised to incubator types. Wider implications of the findings Culture in the Embryoscope increases the frequency of high-quality usable blastocyst development when compared to a MINC. Importantly, this translates to a higher pregnancy rate and live birth rate from fresh embryo transfers. This may be due to the microwell dishes, incubator performance, embryo selection or all of these. Trial registration number Not applicable

P-681 Embryo utilisation rate and blastocyst formation rate correlate negatively with the oocyte yield and positively with live birth rate: an analysis from HFEA’s national database

Abstract Study question Do embryo utilisation rate (EUR) and blastocyst formation rate (BFR) correlate with oocyte yield and livebirth rate (LBR) in fresh IVF/ ICSI cycles? Summary answer EUR and BFR correlate positively with livebirth rate (LBR) but decline with increasing number of oocytes to a nadir when the fresh cycle LBRs plateaus. What is known already LBR in fresh IVF cycles plateaus once a certain number of oocytes are retrieved. While impaired endometrial receptivity with high ovarian response appears to be an underlying cause, other factors, such as decreasing competency of oocytes or embryos cannot be ruled out. Cytoplasmic dysmorphism of oocytes and chromosomal disorders have been shown to rise with increasing number of oocytes. Consequently, cumulative livebirth rate per oocytes has been reported to decline with increasing oocyte yield. When obvious male factor is excluded, the competency of oocytes can be reflected in the embryo grading. Study design, size, duration Retrospective analysis of 8015 fresh IVF/ ICSI cycles that met the inclusion criteria from the national database published by Human Fertilisation and Embryology Authority (HFEA) in the United Kingdom. We analysed 2 years of published data between January 2015 and December 2016. Participants/materials, setting, methods Population included couples at their first IVF treatment with single fresh blastocyst transfer, due to tubal or unexplained infertility among women aged <40 years. Only cycles that produced at least 1 transferable blastocyst were included to determine the blastocyst formation rate. Inclusion criteria were designed to minimise other co-factors that may influence embryo quality. Linear regression analysis was done to find the correlation between EUR/ BFR and oocyte yield; multiple regression to predict livebirth Main results and the role of chance EUR (correlation coefficient = -0.156605, p < 0.0001) and transferable BFR correlation coefficient = -0.156605, p < 0.0001) declined with increasing number of oocytes. The findings were no different whether IVF or ICSI was performed. Both EUR (OR 1.002, CI 1.001- 1,004) and (transferable) BFR (OR 1.005, CI 1.003-1.006) correlated positively with LBR (p < 0.0001, for both), after adjusting for other confounders including age and method of insemination. Both (transferable) BFR and EUR declined with the increasing number of oocytes falling to a nadir when around 8 oocytes were retrieved then remained static with higher oocyte yield. LBR in fresh cycles also reaches its peak at around 8 oocytes then plateaus. Limitations, reasons for caution Information on patient’s BMI or stimulation dose is not available in the HFEA database. However, it might have little impact in our findings given large sample size. Cycles with no blastocyst formation through extended culture were not included, as this intention to treat information was not available Wider implications of the findings Declining proportion of competent embryos may result in flattening of LBR graph in fresh cycles after certain number of oocytes retrieved. Increasing absolute number of competent embryos fails to boost fresh cycle LBR after a saturation point, We have to improve embryo selection than increasing ovarian stimulationto improve fresh LBR Trial registration number NA

P-783 Obstetric and neonatal outcomes after single vitrified-thawed vs. fresh blastocyst transfer: a population-based linkage study

Abstract Study question Does the transfer of a single vitrified-thawed blastocyst optimise obstetric and neonatal outcomes compared to a single fresh blastocyst transfer? Summary answer A single vitrified-thawed blastocyst transfer is associated with a lower risk of preterm delivery and small-for-gestational-age babies but a higher risk of large-for-gestational-age babies. What is known already Several studies have been performed comparing the outcomes of ART pregnancies after fresh or frozen embryo transfers. Nevertheless, a closer examination of the available studies indicates a significant heterogeneity in terms of the clinical protocols they compare, predominantly in regards to the developmental stage of the embryos (cleavage vs. blastocyst), the number of embryos transferred (single vs. multiple) and the cryopreservation method used (slow-freezing vs. vitrification). The use of single blastocyst transfer and vitrification is currently considered the gold standard of care but relevant studies on the safety of these technologies regarding the obstetric and neonatal outcomes are lacking. Study design, size, duration Autologous ART cycles where a single Day 5/6 embryo was transferred were identified (n = 188,730) in the Australian ART registry (ANZARD) and these were linked with 20,214 birth records (deliveries >20 weeks of gestation or with a weight of > 400gr of the Perinatal Data Collection which had taken place in two Australian States between 1st of January of 2009 and 31st of December of 2016. Cycles including preimplantation genetic testing or assisted hatching were excluded. Participants/materials, setting, methods Two cohorts were formed, the Fresh group, containing 89,299 ART treatment cycles linked to 11,138 PDC birth records, and the Vitrified-Thawed (VT) group, containing 75,596 ART treatment cycles linked to 7,518 PDC birth records. Comparisons of obstetric and neonatal outcomes between these groups were performed using generalized estimating equations to account for the clustered nature of data while also accounting for multiple confounders. Significance level was set at 0.01 to correct for multiplicity of testing. Main results and the role of chance The risk of preterm delivery was significantly lower in the VT group compared to the fresh group (adjusted relative risk-aRR: 0.78, 99% CI 0.69-0.88). This persisted in a sensitivity analysis (accounting for the embryo ranking within each cohort) by comparing pregnancies occurring after the first vitrified-thawed embryo transfer following a freeze-all cycle (VTFA) with the fresh ET group (aRR: 0.71, 99% CI: 0.54-0.94). The probability of pregnancy-induced hypertension was not significantly different between the two groups (aRR: 1.15, 99% CI: 0.99-1.34). There was also no indication of an increased risk of PIH when the VTFA group was compared to the fresh ET group (aRR: 0.94, 99% CI: 0.68-1.30). The probability of SGA was 35% lower in the VT group compared to the fresh ET group (aRR: 0.65, 99% CI: 0.56-0.74). When only VTFA babies were compared with the fresh ET group, then the probability of SGA was 20% lower, but this was not statistically significant. For LGA babies, the risk was significantly higher (∼45%) in the VT group compared to the fresh ET group (aRR: 1.46, 99% CI: 1.30-1.65). The LGA risk remained significantly higher in the VTFA compared to the fresh ET group (aRR: 1.34, 99% CI: 1.04-1.72). Limitations, reasons for caution This is a population-based study using linked administrative datasets; therefore not all confounders could be accounted for. Furthermore, the smaller sample size of the sensitivity analysis combined with the strict level of significance adopted might have rendered some sensitivity analyses underpowered particularly for rare outcomes Wider implications of the findings This analysis shows the differences in obstetric and neonatal outcomes between fresh and frozen embryo transfers studying vitrification and single embryo transfer exclusively. For certain outcomes, it appears that the effects are modified when the embryo ranking within each cohort is accounted for. Trial registration number Not applicable

P-286 Clinical pregnancy after blastocyst culture at a stable temperature of 36.6 °C or 37.1 °C : a prospective randomized controlled trial

Abstract Study question Is there a difference in clinical pregnancy rate after single blastocyst transfer (SET) on day 5, in case of stable culture at 36.6 °C or 37.1 °C? Summary answer Clinical pregnancy rates (CPR, heartbeat at 7 weeks) do not differ between blastocyst culture at 36.6 °C and 37.1 °C for five/six consecutive days. What is known already Since the beginning of IVF, embryo culture has been performed at 37.0 °C; however, the optimal temperature remains unknown. Changes in incubator types have led to significant improvements in temperature control. Stable temperature control, with temperature gradients of 0.1 °C among chambers, is possible in G210 incubators (K-Systems, Coopersurgical). A previous prospective trial at our centre showed that embryo development on day 5/6 was not affected when embryos were cultured at a stable temperature of 36.6 °C or 37.1 °C. Though not powered for clinical pregnancy, culture at 37.1 °C resulted in an increased CPR when compared to culture at 36.6 °C (46.4% vs. 74.2%). Study design, size, duration A prospective randomized controlled trial was performed in a tertiary fertility centre between February 2017 and December 2022. Sample size of 89/89 patients with fresh SET was required achieving 80% power to detect a difference of 0.22 between group proportions (0.43-0.65) at a significance level of 0.05 using a two-sided z-test with continuity correction. Participants/materials, setting, methods Patients were recruited the day before oocyte retrieval based on inclusion criteria (SET on day 5, fresh or frozen ejaculated sperm, female age<40 years, BMI<35m2/kg, <3 cycles for the current child) with final randomization after denudation once six mature oocytes were present. Primary endpoint was clinical pregnancy rate (CPR defined as heartbeat at 7 weeks); secondary endpoints were fertilization, blastocyst development, pregnancy (positive hCG), live birth rate (LBR) and cumulative live birth rate (CLBR). Main results and the role of chance A total of 304 patients were eligible for the study of whom 268 signed the consent, 234 were randomized and 181 received SET on day 5: 90 cultured at 36.6 °C and 91 at 37.1 °C. Patients were on average 32.4 ± 3.5 vs. 32.5 ± 4.2 years old, respectively. No differences were observed in embryological outcomes per cycle between both temperatures: 12.0 ± 3.8 vs. 12.1 ± 3.8 COCs retrieved (p = 0.88), 10.0 ± 3.1 vs. 9.7 ± 2.9 mature oocytes inseminated (p = 0.68) with a maturation rate of 83.2% (901/1083) vs. 81.3% (898/1104) (p = 0.87); 8.0 ± 3.1 vs. 7.9 ± 2.7 normally fertilized oocytes with a fertilization rate of 79.9% (720/901) vs. 80.0% (718/898) (p = 0.96), respectively. On average 1.5 ± 1.7 vs. 1.4 ± 1.9 (p = 0.25) and 1.1 ± 1.1 vs. 0.9 ± 1.0 (p = 0.45) blastocysts were vitrified on day 5 and day 6, respectively. Utilization rate per fertilized oocyte was 44.3% (319/720) vs. 42.1% (302/718) (p = 0.14). A single blastocyst transfer was performed for 181 patients, leading to a pregnancy rate of 72.2% (65/90) vs. 62.7% (57/91) (p = 0.17), respectively. CPR of the fresh cycle was 51.1% (46/90) vs. 48.4% (44/91) [OR (95%CI) 1.05 (0.55-1.96), p = 0.71]. To date, a CLBR of 71.1% (64/90) vs. 65.9% (60/91) (p = 0.64), was achieved respectively; with seven patients in each group with remaining blastocysts and no live birth yet. Limitations, reasons for caution Only a selected patient population with expected good prognosis was eligible for the study. Wider implications of the findings Embryos are capable to tolerate small changes in temperature deviations, demonstrated by their similar implantation potential. Trial registration number NCT03548532

The Relationship between Number of Supernumerary Blastocysts Cryopreserved and Probability of a Live Birth Outcome after Single Fresh Blastocyst Transfer: Analysis of over 10 Thousand Cycles.

The ability to predict the likelihood of a live birth after single fresh embryo transfer is an important part of fertility treatment. While past studies have examined the likelihood of live birth based on the number of oocytes retrieved and cleavage-stage embryos available, the odds of a live birth based on the number of supernumerary blastocysts cryopreserved following a fresh embryo transfer has not been rigorously studied. We performed a retrospective analysis, stratified by age, on patients undergoing their first fresh autologous single day 5 blastocyst transfer to assess relationship between the likelihood of a live birth and number of supernumerary blastocysts cryopreserved. In patients aged <35 years and 35-39 years old, the likelihood of a live birth increased linearly between 1 and 6 supplementary blastocysts and non-linearly if 10 or more blastocysts were cryopreserved. When aged 40 years and above, the likelihood of a live birth increased linearly up to 4 cryopreserved blastocysts and then non-linearly if 10 or more blastocysts were cryopreserved. The present study demonstrated a non-linear relationship between the number of supernumerary blastocysts cryopreserved and the likelihood of a live birth after single blastocyst transfer in the first autologous fresh IVF/ICSI cycle across different age groups.

Systematic use of long-acting intramuscular progesterone in addition to oral dydrogesterone as luteal phase support for single fresh blastocyst transfer: A pilot study.

The need of luteal support after FET is no longer to be proven. Different routes of progesterone administration are available with interindividual differences in metabolization and serum progesterone levels, the latter being highly correlated with pregnancy and delivery rates. The administration of 2 different routes of progestogen significantly improves success rates in FET. The aim of the current study was to investigate the added value to combine intramuscular administration of progesterone to dydrogesterone in fresh embryo transfer. This is a retrospective study from prospectively collected data. Patient, aged between 18 and 43 years old, had received a fresh blastocyst transfer between January 2021 and June 2021. In the first group, all patients received only oral dydrogesterone 10mg, three times a day, beginning the evening of oocyte retrieval. In the second group, patients received, in addition to dydrogesterone, a weekly intramuscular injection of progesterone started the day of embryo transfer. Primary endpoint was ongoing pregnancy rate. 171 fresh single blastocyst transfers have been performed during this period. 82 patients were included in "dydrogesterone only" and 89 patients in "dydrogesterone + IM". Our two groups were comparable except for body mass index. After adjustment on BMI, our two groups were comparable regarding implantation rate, early pregnancy rate (46.1 versus 54.9, OR 1.44 [0.78; 2.67], p=0.25) miscarriage rate, ongoing pregnancy rate (30.3 versus 43.9, OR 1.85 [0.97; 3.53] p= 0.06). Using systematically long acting intramuscular progesterone injection in addition to oral dydrogesterone as luteal phase support seems to have no significant impact on IVF outcomes when a single fresh blastocyst transfer is performed.

Influence of climatic conditions in the mesothermal climate area on pregnancies following elective fresh single blastocyst transfer.

To investigate the effect of climatic parameters in the mesothermal climate area on clinical pregnancy and live birth following fresh single blastocyst transfer. This study investigated clinical pregnancies and live births that resulted from 555 ovarian stimulation cycles followed by fresh single blastocyst transfer. The samples were stratified according to climatic conditions (low T, temperature < 12.9°C; middle T, 12.9°C ≤ temperature < 22.6°C; high T, temperature ≥ 22.6°C; low H, relative humidity < 62.1%; middle H, 62.1% ≤ relative humidity < 66.5%; high H, relative humidity ≥ 66.5%; short S, sunlight duration < 5.2h; middle S, 5.2h ≤ sunlight duration < 6.7h; long S, sunlight duration ≥ 6.7h). Clinical pregnancy and live birth rates among three groups from each climatic parameter were compared. Multivariable analyses were performed to investigate the effects of climatic conditions on blastocyst development, endometrial thickness, clinical pregnancy, and live birth. A statistically significant difference was found in pregnancy rates among low T (48.8%), middle T (37.3%), and high T (36.6%) groups. Multivariable analyses revealed that temperature was associated with clinical pregnancy and live birth rates with adjustment for patient age, BMI, type of ovarian stimulation, endometrial thickness, and expansion grade of the transferred blastocyst. The association between climatic parameters and blastocyst development and endometrial thickness was not confirmed. This study suggests that lower temperatures in the mesothermal climate area could favorably affect the rates of clinical pregnancy and live birth achieved by fresh single blastocyst transfer.

Slightly Elevated Progesterone on HCG Trigger Day Has an Impact on Pregnancy Outcomes of Fresh Single Blastocyst Transfer Cycles Under an Early Follicular Phase Prolonged Protocol Cycle.

The effect of premature progesterone elevation on assisted reproductive technology has been debated. In different ovarian stimulation protocols, ovarian responses, and embryos transferred, conflicting results reside regarding the impact of elevated progesterone on pregnancy outcomes, according to previous studies. In addition, most studies have focused on significantly elevated progesterone levels, eg, above 1.5ng/mL, 1.75ng/mL, 2ng/mL. However, studies focusing on levels that are just slightly elevated are lacking, and some have concluded that such levels have no adverse effects on pregnancy outcomes. Clinical data of patients who underwent early follicular phase prolonged protocol cycle in vitro fertilization/intracytoplasmic sperm injection treatment were collected. Patients were divided into two groups according to progesterone level on the trigger day of human chorionic gonadotropin (HCG): Group 1: <1.0ng/mL and Group 2: 1.0-1.5ng/mL. Differences in baseline characteristics, ovulation promotion, and embryo culture, along with clinical pregnancy outcomes, were compared between the two cohorts. A total of 743 participants were included in this study, of which 587 were included in Group 1 and 156 were included in Group 2. In terms of pregnancy outcomes, Group 2 had a significantly lower clinical pregnancy rate and live birth rate per cycle than Group 1 (64.1% vs 75.7%, p <0.05; 63.5% vs 72.7%, p <0.05). After correction for maternal age, maternal body mass index, infertility duration, basal follicle-stimulating hormone, anti-Müllerian hormone, antral follicle count, total dose of gonadotropin, days of stimulation, and estradiol level on HCG trigger day, slightly elevated progesterone levels (P>1.0ng/mL) remained a risk factor for pregnancy failure in fresh single D5 blastocyst transfer under an early follicular phase prolonged protocol cycle. Slightly elevated progesterone levels on HCG trigger day may negatively affect pregnancy outcomes in early follicular phase prolonged protocol cycles.

Day-3-embryo fragmentation is associated with singleton birth weight following fresh single blastocyst transfer: A retrospective study.

BackgroundPrevious studies have arguably associated poor embryo morphology with low birth weight in singletons following single embryo transfer. However, the association between birth weight and specific morphological features in the cleavage stage remains less known. The purpose of the study was to investigate whether morphological features of embryos at the cleavage stage affect birth weight following blastocyst transfer.MethodsThe single-center retrospective cohort study included 4,226 singletons derived from fresh single cleavage-stage embryo transfer (ET; n = 1,185), fresh single blastocyst transfer (BT; n = 787), or frozen-thawed single blastocyst transfer (FBT; n = 2,254) between 2016 and 2019. Morphological parameters including early cleavage, day-3 fragmentation, symmetry, blastomere number, and blastocyst morphology were associated with neonatal birth weight and birth weight z-score in multivariate regression models. The models were adjusted for maternal age, body mass index (BMI), parity, peak estradiol level, endometrial thickness, insemination protocol, female etiologies, order of transfer, mode of delivery, and year of treatment.ResultsAdjusted for confounders, day-3 fragmentation was the only morphological feature associated with birth weight and birth weight z-score, while early cleavage, symmetry, blastomere number, and blastocyst morphology were not. Day-3 fragmentation increased the birth weight in both the ET (115.4 g, 95% CI: 26.6–204.2) and BT groups (168.8 g, 95% CI: 48.8–288.8) but not in the FBT group (7.47 g, 95% CI: -46.4 to 61.3). The associations between birth weight and these morphological parameters were confirmed through birth weight z-score analyses. The adjusted odds of large for gestational age (LGA) and high birth weight were also significantly greater in singletons following the transfer of fragmented embryos in the BT group [odds ratio (OR) 3, 95% CI: 1.2–7.51 and OR 3.65, 95% CI: 1.33–10, respectively]. The presence of fragmentation at the cleavage stage also affected the association between the blastocyst morphology and birth weight. Inner cell mass grades were negatively associated with birth weight in blastocysts with day-3 fragmentation but not in blastocysts without.ConclusionsThe birth weight following blastocyst transfer was found to be positively associated with fragmentation at the cleavage stage. The data did not support the argument that transferring a poor-looking embryo may increase the risks of low birth weight. However, concerns for LGA infants remain.

The influence of morphologic grading and COS protocol on the outcomes of Day 5 versus Day 6 single fresh blastocyst transfers: a retrospective analysis of clinical outcomes from one center experience.

The purpose of this study was to evaluate whether the blastocyst morphologic grading and the protocol of controlled ovarian stimulation (COS) would influence pregnancy outcomes, aiming to provide guidance when choosing blastocyst transfer. The clinical data of 612 patients who received single fresh blastocyst transfer for first cycle, as well as the data of 253 patients who had already delivered were analyzed retrospectively. The patients were divided into two groups according to blastocyst formation time (D5 or D6). The following subgroup analyses were performed: (i) the morphologic grading of blastocyst and (ii) the protocol of COS. We observed that D5 single embryo transfer (SET) were associated with higher clinical pregnancy rate (CPR, 59.04% vs. 31.73%, P < 0.001) and live birth rate (LBR, 43.90% vs. 24.04%, P < 0.001) than D6 SET following fresh cycle. Patients in D5 group experienced more good blastocysts transfer (45.47%vs. 13.46%, P < 0.001) and less poor blastocysts transfer (9.64%vs. 45.19%, P < 0.001) than patients in D6 group. As to early stage and good quality blastocysts, the CPR and LBR were similar between D5 and D6 group. GnRH antagonist protocol had a demonstrable inferiority comparing with the early-follicular-phase long-acting GnRH-agonist long protocol (EFLL) or the mid-luteal-phase long-acting GnRH-agonist long protocol (MLLL) with regard to the CPR and LBR in D6-SET group. The analysis found that ovarian reserve of patients in D6-SET group was comparatively worse than that of patients in D5-SET group and D6-SET patients represented a subgroup of infertility patients usually having relatively poor embryo quality. The results should be interpreted with caution as the very low numbers in the respective group limited the use of statistical tests and the real significance values.

O-290 Cumulative live birth rates in a freeze-all and fresh transfer strategy after one complete ART cycle in ovulatory women

Abstract Study question Is the cumulative live birth rate(CLBR) similar following a freeze-all and fresh transfer strategy including nearly all subsequent frozen-thaw cycles from the same oocyte retrieval? Summary answer The chance of at least one live birth after use off all fresh and frozen blastocysts is similar following a freeze-all and fresh transfer strategy What is known already Traditionally, ART success rates have been reported as pregnancies per fresh cycle or per embryo transfer. Advancements such as blastocyst culture and vitrification have enhanced survival and improved live birth rates. This facilitates single blastocyst transfer, a steadily increasing use of vitrified-warmed transfers, and a growing implementation of elective freeze-all cycles worldwide. Hence CLBRs, defined as the proportion of deliveries with at least one live birth following the use of all fresh and frozen embryos derived from one ovarian stimulation cycle, constitutes a better measure of IVF treatment success providing an all-inclusive success rate for ART. Study design, size, duration CLBR was a secondary outcome in a multicentre randomised trial with allocation 1:1 to (A) Freeze-all strategy involving GnRH agonist trigger and single vitrified-warmed blastocyst transfer in consecutive modified-natural FET cycles or (B) Fresh transfer strategy with hCG trigger and fresh single blastocyst transfer followed by consecutive single blastocyst FET cycles. The minimum follow-up time from the start of ovarian stimulation was 2 years. Participants/materials, setting, methods 460 women initiating their 1.,2. or 3. ART cycle at eight different clinics in Denmark, Sweden and Spain. The GnRH antagonist protocol and modified-natural frozen-thaw cycles with single blastocyst transfer were applied. Cumulative live birth was defined as at least one live birth per woman after all fresh and/or frozen cycles from a single ovarian stimulation. Women were followed until the first live birth. Analyses were performed according to the ITT principle. Main results and the role of chance Baseline and treatment-related characteristics were similar between the two groups and a similar proportion of women had additional frozen-thawed embryo transfers following the initial fresh or frozen transfer. Combining all fresh and/or frozen transfers from the included oocyte retrieval with a minimum of 2-years of follow-up, the cumulative live birth rate was 42.6% (95/223) in the freeze-all group versus 41.7% (96/230) in the fresh transfer strategy group (risk ratio (RR): 1.0; 95%CI 0.87-1.19, P = 0.93). The median (IQR) time to first pregnancy was 106.0 (80.5-156.5) versus 29.0 (27.0-113.5) days in the Freeze all and Fresh transfer group, respectively. Of all subsequent frozen transfers, a total of 34/103 (33%) cycles resulted in a live birth in the freeze all group compared with 29/108 (26.9%) in the fresh transfer group (risk ratio (RR): 1.09; 95% CI 0.91-1.3; P = 0.41). Finally, a total of three (1.3%) and eight (3.5%) blastocysts in the freeze all and fresh transfer strategy group respectively, did not survive the freezing thawing process (p = 0.24). The number of women with unused cryopreserved embryos at the end of the 2-year follow-up period was four (0.9%) in the freeze all and seven (1.6%) in the fresh transfer group. Limitations, reasons for caution The primary RCT outcome was ongoing pregnancy rate following two treatment strategies within the ART regimen hence two different ovulation trigger modalities were applied, introducing a risk of bias. Furthermore, despite a 2-year follow-up few women (2.4%) still had cryopreserved embryos and no live birth at the end of follow-up. Wider implications of the findings Advancements of embryo culture and freezing-thawing techniques facilitate an elective single embryo transfer policy. CLBRs provide an all-inclusive success rate for ART. A freeze-all strategy can be used as an alternative to a fresh transfer strategy in women at risk of OHSS as CLBRs are similar. Trial registration number NCT02746562

Endometrial Thickness Is a Risk Factor for Singleton Low Birth Weight From Single Blastocyst Transfer: A Retrospective Cohort Study.

ObjectiveTo explore whether endometrial thickness (EMT) ≤7.5 mm is associated with singleton low birth weight (LBW) from single fresh blastocyst transfer.MethodsThis was a retrospective cohort study. Only women ≤ 40 years old who underwent single fresh blastocyst transfer and had singleton live births were included in the study. LBW was the primary outcome of this study. Neonatal malformation was the secondary outcome. Logistic regression was used to evaluate the association between (EMT) ≤7.5 mm and singleton LBW.ResultsA total number of 2847 women met the study inclusion criteria. The neonatal birthweight in the EMT ≤7.5 mm group was significantly lower than that in the EMT 7.6~12.0 mm and EMT >12.0 mm group (P<0.001). The rate of LBW in the EMT ≤7.5 mm group was 24.9%, which was significantly higher than the 4.0% in the EMT 7.6~12.0 mm group and the 5.3% in the EMT >12.0 mm group (P<0.001). The total neonatal malformation rate was similar between the groups (1.1%, 0.8% and 1.5%, P=0.21). After logistic regression analysis, EMT ≤7.5 mm was found to be an independent risk factor for LBW (adjusted odds ratio [AOR]: 4.39, 95% CI: 1.85˜10.46, P<0.001).ConclusionEMT ≤7.5 mm on the hCG trigger day is an independent risk factor for LBW in singleton pregnancies from single fresh blastocyst transfer. The neonatal birthweight in the EMT ≤7.5 mm group was significantly lower than that in the EMT 7.6~12.0 mm and EMT >12.0 mm groups. The total neonatal malformation rate was comparable between the groups.

P–498 Patient’s pregnancy rates after IVF fresh embryo transfer positively correlates to the number of visual connections to live blastocyst development images of own embryos

Abstract Study question Looking at time-lapse images of own embryos during the five days of culture, as a patient’s active behaviour, may help to increase pregnancy rates? Summary answer The number of visual connections to live blastocyst development images of own embryos positively correlates to patient’s pregnancy rates after fresh single blastocyst transfer. What is known already In human reproduction, despite the evidence that infertility itself and reproductive treatments can produce anxiety and stress, the impact of emotions on pregnancy outcomes is unknown and probably underestimated. The interaction between psyche, nervous, immune and endocrine systems (PNIE) is well known and has been applied to understand and treat different pathological conditions. Patient’s active behaviour during IVF treatments appears to be a positive strategy to decrease women’s anxiety and stress, thus to increase fertility quality of life and pregnancy outcomes. Study design, size, duration Retrospective comparative study of 934 patients undergoing fresh IVF cycles during three years. To avoid any bias related to oocyte and embryo factors, we only included egg donation cycles in the study, and ≥3BB (Gardner score) single embryo transfers. All embryo cultures were performed in time-lapse incubator and patients could connect on-line to their embryo’s images before single blastocyst transfer. We evaluated the impact of visual connections to live embryo images on pregnancy rates. Participants/materials, setting, methods On day one of embryo culture, consenting patients received an individualized and secure link allowing them to connect on-line to images of their own embryos any time during the five days of culture. Patients were divided in five groups depending on the number of on-line visualisations (A = 0; B = 1–10; C = 11–20; D = 21–30; E &amp;gt; 30). Pregnancy and clinical pregnancy rates were compared between the five groups. Chi-square test for a large contingency table was performed to compare all groups Main results and the role of chance The distribution of patients in the five groups, based on number of visualizations, resulted as follows: 287 in group A; 328 in group B; 156 in group C; 80 in group D; 83 in group E. The five groups were homogeneous and there were no statistically significant differences in recipient’s ages (A 42.8±3.9 years; B 41.9±3.9 years; C 41.8±4.5 years; D 42.8±4.1 years; E 41.9±4.4 years) and in donor’s ages (A 25.5±4.3 years; B 26.9±4.4 years; C 27.1±4.2 years; D 26.4±4.5 years; E 26.5±4.1 years) among the five groups. We observed a progressive positive trend between the number of on-line visualisations and pregnancy rates, reaching statistical significance for group E (&amp;gt;30 visualizations) compared to the others groups. In group E, pregnancy rates and clinical pregnancy rates per fresh single blastocyst transfer were respectively 72.3% and 65.1%, significantly higher when compared to the others groups (p &amp;lt; 0.01, p &amp;lt; 0.001): group A 61% and 50.9%, group B 63.1% and 56.1%, group C 64.1% and 55.1%, group D 65% and 53.8%. Limitations, reasons for caution Time-lapse incubator is needed as well as a strong informatics setting to ensure secure and personalised on-line connection to each patient at any time during the five days of culture. Endocrine and endometrial biomarkers should be proposed and evaluated in further clinical trials to better understand these results. Wider implications of the findings: Repeated on-line visualization of own embryos images before fresh blastocyst transfer enhances pregnancy rates in IVF cycles. We propose that repeated visual stimuli of images produces a positive emotional connection between patients and their own developing embryos, thus reducing anxiety and enhancing recipient’s endometrial receptivity. Trial registration number Not applicable