Higher Pregnancy Rates Research Articles

Effect of melatonin implantation prior to ovsynch plus cidr protocol on subsequent ovarian activity and pregnancy rate in summer anestrous Murrah buffaloes

For assessing the impact of melatonin pre-treatment in summer anestrous Murrah buffaloes on subsequent reproductive activity of a fixed time artificial insemination (FTAI) protocol, 83 anestrous Murrah buffaloes were subcutaneously inserted 2x4 mm size absorbable melatonin (MT) implants (18 mg/50 kg b wt) at the base of left ear and 38 Murrah buffaloes were used as non-implanted controls. On day 35 post-MT, the treatment and control group Murrah buffaloes were subjected to FTAI protocol (Ovsynch plus CIDR). Ovarian ultrasonography and jugular vein blood sampling was carried out on day 7 and 10 of protocol and on day 7-post AI. Overall pregnancy rate on day 90 post-AI in MT group was higher compared to control group (55.4 vs 31.6%, P<0.05), along with the higher (P>0.05) plasma progesterone on day 7 of FTAI protocol in Murrah buffaloes of the former group which conceived subsequently compared to their non-pregnant counterparts. Moreover, MT group had higher (P>0.05) increase in dominant follicle diameter between day 7 and 10 of protocol compared to control group. On day 7 post-AI, the luteal profile in pregnant murrah buffaloes of MT group was better (P<0.05) compared to their counterparts in control group (CL: 14.80±0.70 vs 10.82±0.46 mm, P4: 1.54±0.07 vs 1.04±0.08 ng/ml). In conclusion, melatonin pre-treatment in summer anestrous Murrah buffaloes could be associated with better luteal activity and higher pregnancy rate in the Ovsynch+CIDR protocol.

Modern Contraceptive Use and Associated Factors In USSA Local Government Area Of Taraba State, Nigeria

With the high rate of unintended pregnancy in the world, encouraging the use of contraceptives has become necessary. However, there are factors that may influence whether a woman agrees to use contraceptives or not. Thus, this study assessed the factors that determine the use of contraceptives among women in Ussa Local Government Area of Taraba State. The specific objectives of the study were to determine the effect of cultural beliefs, socioeconomic status, attitude of conceptive providers, education level and shortages of contraceptives on the use of modern contraceptives in Ussa Local Government Area of Taraba State. The study employed literature-based analysis and found out that level of education, cultural beliefs and practices, shortages of health facilities, attitude of contraceptive providers, sex education, socioeconomic status play major role in determining women’s use of contraceptives among women in Ussa Local Government Area of Taraba State. The paper recommended that, there should be an increase supply contraceptive in all places timely and optimally through involving voluntary, religious and private health facilities in provision to ensure availability.

O-132 Comparison of pregnancy rates in antagonist cycles after luteal support with GnRH-agonist versus progesterone – prospective randomized study

Abstract Study question Are pregnancy rates in GnRH-antagonist cycles triggered with hCG and luteal phase support (LPS) with intranasal GnRH-agonist or vaginal progesterone comparable? Summary answer Nasal GnRH-agonist for LPS is associated with higher pregnancy rates compared with standard progesterone support in antagonist-based cycles triggered with hCG What is known already Regardless of its mechanism of action, the use of GnRH-a during the luteal phase in addition to progesterone, either in a single or multiple doses, has become a common practice as a part of ART protocols, based on its association with higher pregnancy and live birth rates . Its use as a sole agent for LPS has not gained the same popularity although studies supporting non-inferiority and even higher live birth rates with GnRH-a as a sole LPS agent have been published. Study design, size, duration A single-center, prospective, randomized study. A total of 150 patients underwent 164 GnRH-antagonist-based IVF cycles triggered with hCG and fresh embryo transfer. The study was conducted between June 9th, 2020, and May 5th, 2022. Participants/materials, setting, methods The study was conducted in the IVF clinic at University-affiliated tertiary medical center. Patients meeting the inclusion criteria who underwent antagonist-based IVF cycles and hCG triggering were enrolled. Computer-based randomization (1:1 ratio) was performed on the day of oocyte pickup (OPU). In both groups LPS was initiated on the evening of the OPU day with either GnRH-agonist nasal spray (Nafareline, nasal spray 200 mcg twice daily)or vaginal micronized progesterone (Utrogestan 300 mg, 3 times daily). Main results and the role of chance A total of 150 patients underwent 164 cycles, 127 cycles of which were included in the study cohort. Of them, 64 (50.4%) and 63 (49.6%) cycles were treated with GnRH-agonist or progesterone respectively as sole luteal phase support. A significantly higher pregnancy rate was found in the GnRH-a group compared with the progesterone group (43.8% versus 25.4% respectively; P = 0.030). After adjustment of several potential confounders such as age, body mass index (BMI), past obstetric history, number of IVF cycles, oocytes retrieved and embryos transferred, GnRH-agonist was still associated with a higher pregnancy rate (odds ratio 3.4, 95% confidence interval 1.4-8.3). Ovarian hyperstimulation syndrome (OHSS) rates were similar between the groups. Significantly higher progesterone levels were measured at β-hCG testing day in the GnRH-a group, both for the cleavage stage embryos (129.1±23.7 nmol/L vs. 97.7±48.9 nmol/L, P = 0.024) and for the blastocysts (127.2±0.1 nmol/L vs. 75.3±49.1 nmol/L, P = 0.034). Limitations, reasons for caution This study is not powered for analysis of clinical pregnancy rates, live birth rates and pregnancy outcomes. Larger studies are needed for research of these outcomes. All patients participating were at low risk for OHSS, therefore the study is underpowered to find significant differences in early or late OHSS.Wider implications of the findings Our findings suggest that intranasal GnRH-agonist administration as a sole luteal support in antagonist-based IVF cycles triggered with hCG results in higher pregnancy rates in comparison with traditional irritating vaginal preparations while not mandating additional support in the first weeks of pregnancy. Trial registration number Clinicaltrials.gov - NCT05484193

P-369 An innovative approach for FET that does not rely on the luteinizing hormone surge or human chorionic gonadotropin: a natural cycle with luteal support

Abstract Study question Can progestin supplementation in natural cycle, without reliance on LH surge or hCG ovulation triggering, effectively prepare the endometrium for a frozen embryo transfer (FET)? Summary answer High pregnancy rates can be achieved in natural cycle using luteal support as the main method for endometrial synchronization, without relying on the LH surge What is known already In recent years, frozen-thawed embryo transfer has become widely adopted and plays a significant role in assisted reproductive technology. To date, the evidence suggests that natural cycles result in higher pregnancy rates and fewer obstetric complications compared to hormonal replacement therapy, however, the most effective method for preparing the endometrium has not yet been determined. For transfer in the natural cycle specifically, conflicting results have been reported in terms of the outcome following spontaneous or triggered ovulation. No research is available that supports a natural cycle FET without monitoring the endogenous LH surge or using hCG trigger. Study design, size, duration This is a prospective analysis of 508 natural FET cycles between March 2019 and December 2022, including patients receiving embryos with own oocytes (339) and donated oocytes (169). Participants/materials, setting, methods All patients underwent ultrasound monitoring and serum hormone levels determination of estrogen and progesterone in 3 moments of the cycle (the day of the start of luteal support, 1 week before B-HCG and the day of B-HCG). Upon ultrasound confirmation of the endometrium's optimal thickness and appearance and the presence of the pre-ovulatory follicle, patients began progesterone supplementation and the day for FET was scheduled. Main results and the role of chance A clinical pregnancy rate of 65.48% was reported with a miscarriage rate of 9.09%. A higher rate of miscarriage (22.22%) was found to be associated with an endometrial thickness of less than 7mm at the time of progesterone initiation. The size of the dominant follicle did not affect pregnancy outcome, but a higher pregnancy rate was observed when the follicle measured 15 mm or larger (CPR of 66.83% in cycles with a follicle ≥15mm versus CPR of 60.22% in cycles with a follicle <15mm). Estrogen levels decline in the second measurement but increase again on the day of a positive beta test. This protocol requires less monitoring compared to true and modified natural cycles and is convenient to coordinate with oocyte recipients. A thin endometrial lining, measured below 7mm, increases the risk of a clinical miscarriage. A lack of increase in estrogen levels on the day of B-hCG is an unfavorable sign for a positive outcome. Limitations, reasons for caution Our analysis of data has a prospective design, although it may be limited by unmeasured factors such as the number, stage, and chromosomal testing of transferred embryos. Wider implications of the findings Supplementary luteal support does not affect the natural progression of the endometrium towards receptiveness and results in a key intervention for controlling the start, length and functionality of the window of implantation. A natural cycle, with progesterone supplementation but without monitoring the LH surge, results in high pregnancy rates. Trial registration number Not applicable

O-005 The ToF-study - comparing the cumulative live birth rate of blastocyst-stage versus cleavage-stage embryo transfers in good prognosis IVF patients: a multicenter randomized controlled trial.

Abstract Study question Does blastocyst-stage embryo transfer in fresh and frozen cycles improve the cumulative live birth rate (cLBR) compared with cleavage-stage embryo transfer in IVF/ICSI treatments? Summary answer In good prognosis IVF patients (≥4 available embryos), a blastocyst-stage transfer policy did not result in a significant higher cLBR compared to cleavage-stage transfer policy. What is known already A recent Cochrane systematic review and meta-analysis concluded that fresh blastocyst-stage transfer in IVF/ICSI treatments is associated with higher rates of pregnancy in comparison to fresh transfer of cleavage-stage embryos. However, it is unknown whether a blastocyst-transfer policy also improves the cumulative live birth rate, i.e. the live birth rate derived from fresh and frozen-thawed embryo transfers following a single oocyte retrieval, in comparison to a cleavage-stage transfer policy in IVF/ICSI. Study design, size, duration In this multicenter randomized controlled trial women were randomly allocated to blastocyst-stage transfers (blastocyst group - fresh embryo transfer on day 5 after oocyte retrieval followed by vitrification of remnant blastocysts on day 5 and 6 following local criteria) or cleavage-stage transfers (cleavage-stage group - fresh embryo transfer on day 3 after oocyte retrieval followed by embryo cryopreservation on day 3 or 4). Randomization was stratified for age (≥36 or < 36 years). Participants/materials, setting, methods Women with a good prognosis after IVF/ICSI (defined as presenting ≥4 available embryos on day 2 of embryo culture), during their first, second, or third treatment cycle, were included. The primary outcome was the cLBR per oocyte retrieval, including associated frozen-thawed embryo transfers within 12 months after randomization (or 17 months during the COVID pandemic). Risk ratios (RR) with 95% CI adjusted for age group were calculated using log-linear binominal regression. Main results and the role of chance A total of 1202 women from 21 Dutch centers were randomly assigned to blastocyst-stage transfers (N = 599) or cleavage stage transfers (N = 603) between 2018 and 2021. At submission of this abstract, data on the primary outcome was available for 1153 (95.9%) women, 577 women in the blastocyst-stage group and 576 women in the cleavage-stage group. The cumulative live birth rate was 58.2% (336/577 women) in the blastocyst-stage group and 57.3% (330/576 women) in the cleavage stage group (RR 1.022, 95% CI 0.844-1.237; p = 0.825). The live birth rate after fresh embryo transfer was 38.0% (219/577 women) versus 29.9% (172/576 women) in the blastocyst-stage group and cleavage-stage group respectively (RR 1.282, 95% CI 1.017-1.615 p = 0.035). Interaction was found between age and day of transfer with a higher cumulative live birth rate and a higher live birth rate after fresh transfer in women of 36 years or older in the blastocyst group. Analyses on other IVF treatment outcomes, obstetrical or neonatal outcomes, patient burden, and cost effectiveness are ongoing. Limitations, reasons for caution Outcomes are only applicable for treatments of women with at least four embryos available on day two of embryo culture. Wider implications of the findings A blastocyst-stage embryo transfer policy did not result in a significant higher cumulative live birth rate in comparison to a cleavage-stage embryo transfer policy in IVF/ICSI treatments. Further research into the interaction of age with outcomes is warranted. Trial registration number NTR7034

P-479 Prognosis for ongoing pregnancy after recurrent implantation failure (RIF) following IVF/ICSI treatment

Abstract Study question What is the cumulative ongoing pregnancy rate within one year after visiting the RIF outpatient clinic in patients with RIF after IVF/ICSI treatment? Summary answer The cumulative ongoing pregnancy rate was 42.9% with a mean time to pregnancy of 8.8 months (95% CI 7.5-10.1 months). What is known already An estimated portion of 10-15% of IVF patients experience RIF. Multiple add-on treatments have been proposed, however, evidence for effective clinical therapeutic options still remain scarce. Although it is described that RIF patients might eventually benefit most from a ‘keep calm and carry on’ approach, in practice patients often seek clearer answers on their pregnancy chance and request further investigations/interventions. It would be helpful to give patients insight in their chances of achieving pregnancy after RIF, but at this moment little is known about their prognosis. This is further complicated by the lack of consistency in the definition of RIF. Study design, size, duration A prospective cohort study on 42 RIF patients after one-year follow-up was performed, as part of the MURIM (Multidisciplinary Research on Repeated Implantation Failure and Recurrent Miscarriages) study. Baseline characteristics including an endometrial assessment and ReceptIVFity (vaginal microbiome) test were collected at the RIF outpatient clinic. After a follow-up duration of minimal one year participants were asked to complete a questionnaire regarding fertility treatment and pregnancy outcome. Missing information was received via medical files. Participants/materials, setting, methods RIF patients aged 18 to 38 years old visiting the RIF outpatient clinic at Maastricht University Medical Centre+ between April 2019 until September 2021 were included. RIF was defined as consecutive implantation failure of three high quality embryos or ten embryos without a quality criterion. Clinical characteristics, pregnancy outcome and time to pregnancy was analyzed by survival analysis and cox hazard regression analysis via SPSS version 20.0. A p-value of < 0.05 was considered statistically significant. Main results and the role of chance Forty-two out of 44 contacted patients responded to the questionnaire (response rate = 95.5%). The ongoing pregnancy rate was 42.9% (Standard Deviation (SD): 0.50%) during the first year after visiting the RIF outpatient clinic. Mean time to ongoing pregnancy was 8.8 months (95%-CI: 7.5-10.1 months). The mean amount of embryo transfers (ETs) during this year was 2 (SD: 1.78). The ongoing pregnancy rate per ET (by survival analysis) for the first, third and sixth ET was 33.1%, 49.3% and 63.8%, respectively. To correct for a possible overestimation of the cumulative ongoing pregnancy rate per ET by normal survival analysis, pregnancy rates were calculated again using the number at risk of the total group during the first ET (pessimistic cumulative pregnancy rate). The pessimistic cumulative ongoing pregnancy rates were 33.1%, 42.9% and 48.6%, respectively. When comparing baseline characteristics by univariable cox hazard regression between women with and without ongoing pregnancy, no significant differences were found. Nineteen pregnancies were reported during the one-year follow-up, one conceived spontaneously (5.3%); four via fresh ET (IVF=15.8% and ICSI=5.3%); and 14 by frozen ET (IVF=26.4% and ICSI=47.4%). The pregnancies resulted in 14 livebirths (73.7%); one miscarriage (5.3%); one stillbirth (5.3%); and three ongoing pregnancies (15.8%). Limitations, reasons for caution Although this is the first study that prospectively describes pregnancy prognosis after RIF, it is limited by the short follow-up period and relatively small sample size. The RIF outpatient clinic consultation might have contributed to the obtained pregnancy results but the proportionality is unclear as there is no control group. Wider implications of the findings The obtained ongoing pregnancy prognosis after RIF is encouraging and justifies a conservative approach after three failed ETs. Furthermore, the high pregnancy rate indicates the need of well-defined, individualized diagnostic criteria to define RIF and to be able to deviate between couples with 'bad luck' and an underlying (treatable) cause. Trial registration number NL66835.068.18/METC18-040

P-599 The use of serum test to detect the LH surge in ultrasound-monitored intrauterine insemination (IUI) significantly increases pregnancy rates.

Abstract Study question Could a serum test to detect LH surge in ultrasound-monitored IUI cycle improve pregnancy rates? Summary answer Serum test to detect LH surges with ultrasound monitoring during IUI cycle significantly increased pregnancy rates. What is known already IUI is known as the first line of treatment for infertile couples and is usually administered with human chorionic gonadotropin (hCG) before ovulation with clomiphene citrate (CC) or/and human menopausal gonadotropin (hMG) to ovarian known to stimulate. One of the key factor for IUI is that insemination should be performed close to ovulation time, as there are many reports that sperm injection at the ovulation time has a high pregnancy rates. However, there are still few reports on the optimal timing of ovulation for performing IUI. Study design, size, duration The IUI performed from January 2016 through November 2022 (n = 3187) was included in this study. A total of 875 patients underwent the IUI by inferring LH surge with procedure with serum test, while 2312 patients underwent the procedure IUI without the serum test (control). Participants/materials, setting, methods In this study included 3187 IUI cycle were analyzed. Controlled ovarian hyperstimulation was conducted with CC (100 mg/day) and hMG. Patients were divided into two groups with serum test or not test (control). The serum test group was monitored LH surge by inferring LH peak during IUI cycle. When the sufficient follicular size and endometrial thickness had been reached, hCG was administrated and insemination was performed. Pregnancy rates were compared by Chi-squared test. Main results and the role of chance In each group, there were no significantly difference in age (34.4±3.7 vs. 34.7±3.7 years old) and endometrial thickness (8.8±2.2 vs. 8.9±2.2 mm) for IUI cycle condition. The serum test group was significantly higher clinical pregnancy rates compared to control group (19.0 vs. 15.7 % respectively) during IUI cycle (P < 0.05). In addition, patients were classified according to the history of at least one or more failed IUI cycle. The clinical pregnancy rates was significantly higher in the serum test group than control group (21.6 vs. 10.8 % respectively) who history of at least one or more failed IUI cycle (P < 0.001). Limitations, reasons for caution A limitation of this study has a too small size of the intervention group compared with the control group. Wider implications of the findings In our results, the serum test group had a significantly higher clinical pregnancy rates than the control group. Therefore, detecting a surge in LH with a serum test during the IUI cycle could predict the optimal timing of ovulation and thus increase the pregnancy rates. Trial registration number not applicable

P-140 Relationship between re-expansion rate of vitrified blastocysts during recovery culture post-warming and pregnancy rate after single blastocyst transfers

Abstract Study question What is the relationship between re-expansion rate of vitrified-warmed blastocysts and pregnancy rate after single blastocyst transfers (SVBT)? Summary answer Re-expansion rate of vitrified-warmed blastocysts was higher with increasing the number of TEs and yielded higher pregnancy rate after SVBT. What is known already The increased use of blastocyst transfer has emphasized the importance of selecting high-quality embryos. Pre-vitrification morphological grading: Gardner’s criteria or time-lapse imaging of embryo morpho kinetics and developmental speed, is established a tool for selection of high-quality blastocysts. The recovery culture of vitrified blastocysts post-warming is performed before embryo transfer. Embryos that have dehydrated and shrunk during vitrification are restored to their pre-vitrification state during the recovery culture. Developmental competence in vivo of re-expanded blastocysts after thawing was higher than that of non-expanded blastocysts, but it is not clear the relationship between the re-expansion rate and the pregnancy rate, quantitatively. Study design, size, duration We analyzed 1034 vitrified-warmed blastocysts in 758 patients from July 2017 to June 2021. All embryos were monitored by a time-lapse system (EmbryoScope+, Vitrolife). Expanded blastocysts which reached the blastocoel cavity of 160 µm or more with obvious ICM were vitrified and cryopreserved. The blastocysts were transferred in the following cycle or later. Fetal heartbeat was detected as the pregnancy confirmation. Participants/materials, setting, methods The re-expansion rate was defined as the percentage of re-expanded blastocyst diameter after the recovery culture to the blastocyst diameter at the time of vitrification. The time of recovery culture was about 3 hours. The re-expansion rate and pregnancy rate were analyzed by logistic regression analysis. We also examined the association between re-expansion rate and the number of trophectoderm cells at equatorial region (eTE) or iDAScore: the parameters for selecting high-quality embryos. Main results and the role of chance Logistic regression analysis showed a significant relationship between re-expansion rate and pregnancy rate (P < 0.0001), with an AUC of 0.58 and a cutoff value of 88.5%. Pregnancy rates in re-expansion rates ≥ 88.5% were significantly higher than those in < 88.5% (51.7 vs. 37.4%). Therefore, we classified re-expansion rates ≥ 88.5% as positive and < 88.5% as negative, and performed logistic regression analysis of women age, vitrification time of blastocysts, eTE, and iDASCore. The results showed that women age, vitrification time, and iDAScore all did not differ significantly from the re-expansion rate. The number of eTE was significantly higher with increasing re-expansion rates (P < 0.0001), with an AUC of 0.58 and a cutoff value of 7.5. Limitations, reasons for caution We used only the expanded blastocysts with 160 µm or more in diameter and obvious ICM for vitrification. In addition, this study was retrospective, and further research is needed to confirm the reproducibility of the study in other clinics with different vitrification protocols and patient populations. Wider implications of the findings Quantitative analysis of re-expansion rate of vitrified blastocysts indicated that higher re-expansion rate (≥ 88.5%) had high pregnancy rate. It is useful to exploring the influence factors of re-expansion for producing high-quality embryos. Here, we found that the number of eTE is as an important factor for re-expansion. Trial registration number not applicable

P-189 Systematic management and confirmation of safety (Safety management manual; 7 CHA IVF laboratory instructions; Field training; Lecture; Inspection) can prevent embryo mix-up in IVF laboratory

Abstract Study question Is systematic patient safety management training effective in improving awareness in safety confirmation and preventing errors in Embryo mix-up for embryologists? Summary answer From survey for 116 embryologists, they responded that they followed safety management instructions and regulations, and that they improved their safety work capability and awareness What is known already The cases of embryo mix-up known through the media include errors of sperm change during IUI, fertilization, Freeze-thawing, PGT, and Embryo transfer process, but there will be more due to statistical difficulties. Errors mostly occur because clinics do not have the right protocol. Currently, there aren’t any regulations or policies to track eggs, sperm, embryos or frozen embryos during ART. For this reason, infertile couples have to choose clinics with high pregnancy rates and safe clinics on their own to perform assisted reproductive techniques. Study design, size, duration This study was conducted through a survey of 116 embryologists who worked at five clinics of CHA fertility centers. The patient safety management system was created from the CHA fertility Center itself. From August 2021 to December 2022, safety confirmation training was conducted for 16 months. All embryologists were anonymously surveyed twice with 32 questions. The first survey was conducted in April 2022, and the second survey was in December 2022. Participants/materials, setting, methods The survey was conducted in 32 items with 10 categories. Interviewees’ made response for each item in five steps. Each item asked 1) Learning in the standard safety manual 2) Changes in safety awareness before and after training, 3) Compliance to the seven safety instruction (double checks) for each work part, 4) Level of difficulty in education, 5) Effects of education and 6) Suggestions for safety confirmation. Main results and the role of chance In the first survey, 61 out of 112 responded (54.5%) 60 out of 116 (51.7%) in the second. The answers were scored using a 5-point Likert scale (1 = strong disagree, 5 = Strong agree). 1. The mean score for work satisfaction was 3.1 ± 0.8 out of 5 in the first survey and 3.1 ± 0.7 out of 5 in the second. Work satisfaction remained unchanged. 2. The perception of patient safety confirmation was 3.7/5 before training and 4.0/5 after training (p < 0.03) in the second which improved the perception of safety confirmation. 3. The safety confirmation ability through training was improved to 4.1/5(p < 0.01) after training compared to 3.8/5 in both the first and second surveys. 4. The necessity and importance of safety training were considered important in the first survey as it scored 3.6/5 and 4.5/5 (p < 0.001) in the second survey. 5. In the course of work, they responded that their safety management skills were improved (1st: 3.4/5, 2nd: 4.5/5(p < 0.05)) by the effects of training. As for CHA IVF lab, the embryologists were well aware of the guidelines (scoring 4.5/5 in the first and second survey) to know seven safety instructions (which are double check, outloud, RI witness, monitoring, document, information) should be followed well. Limitations, reasons for caution Embryo mix-up during ART procedures can be a major mistake to be avoided. The confirmed documentations can make errors any time. Establishing the safety protocol of the same process as ART procedure, the system, and education are important, but the most important is the safety management capability of the manager. Wider implications of the findings The safety management manual, the 7 CHA IVF laboratory patient safety instructions, online lecture training, field training, and inspection have raised awareness of the safety errors and the importance of double checking. Errors in safety can be prevented through systematic system development and repeated safety training. Trial registration number non-clinical trials

O-154 ICMART preliminary world report 2019

Abstract Abstract title International Committee for Monitoring Assisted Reproductive Technologies (ICMART) Preliminary World Report on ART, 2019 Study question In 2019 what was the global utilization, effectiveness and safety of ART? Summary answer Globally, ART utilization and data collection continue to increase but with wide variations in utilization, effectiveness and safety. What is known already ICMART began ART global data collection in 1991. Utilization, effectiveness and safety have continuously improved with more cycles, higher pregnancy rates and lower multiple birth rates, the latter due to the transfer of fewer embryos. Frozen embryo transfer (FET) and donor egg cycles continue to increase. However, wide variations in practice and outcomes exist globally. Approximately 10 million ART babies have been born. ICMART has helped develop registries internationally. A new electronic data collection platform has been developed with the University of New South Wales (UNSW) in Sydney, Australia; nevertheless, data collection and quality remain challenging. Study design, size, duration Countries and regions annually collect ART data, some prospectively and others retrospectively. ICMART retrospectively requested data from all known global sources for 2019 and reviewed them for missing or incorrect data. The dataset was reviewed and corrected by ICMART, in partnership with UNSW for validation and analysis, then ICMART finalized the results tables. Standardized definitions from The International Glossary on Infertility and Fertility Care, 2017, and previously developed methods were used. Preliminary results are presented. Participants/materials, setting, methods The European IVF Monitoring Consortium (EIM), Latin American Network of Assisted Reproduction (REDLARA), Australian/ New Zealand Registry and African Network and Registry for ART (ANARA) submitted regional data, and other countries contributed national data, through standardized formats, to ICMART. A few individual clinics with no registry access also contributed. Data received were reviewed, corrected, and validated to the extent possible, analyzed and summarized by ICMART using descriptive statistics. Main results and the role of chance Data collection and analysis are ongoing, so the presented results are preliminary. The number of ART cycles continues to increase, but utilization is still highly variable among countries and regions. Regional and country differences persist in the age of women treated, number of embryos transferred, live birth rates, rate of multiple births, use of ICSI, cryopreservation cycles and other factors. The role of chance is minimal. Actual global ART results are limited to reporting countries and clinics representing 90 to 95% of global cycles. However, this is a very large sample size from which imputation of total global results is performed. Limitations, reasons for caution Most, but not all, countries report to ICMART. Some countries have limited data and many countries have limited data validation. ICMART can perform only minimal verification of submitted data. Widespread adherence to consensus definitions provided in the Glossary takes time and requires translation into multiple languages. Standardization of validation and reporting is an ongoing process because of missing data and continuing changes in clinical practice. Wider implications of the findings ICMART World Reports standardize data, track trends, enable comparisons, stimulate questions and improve ART quality. Better understanding of ART increases societal acceptance and support for equitable access and ART research.

P-498 Towards precision medicine: maternal genetic profiles as determinant of adequate decidualization and reproductive success; a prospective study in oocyte donation cycles.

Abstract Study question To determine the impact of genes related to decidualization and immune cell activation as predictors for reproductive success. Summary answer Women with unfavorable genetic profiles for Human Leukocyte Antigen (HLA)-F and Killer Immunoglobulin-like Receptor (KIR) genes showed decreased pregnancy rates. What is known already KIR genes encode receptors present on uterine Natural Killer (uNK) cells that are essential during placentation and early gestation. It has been established that women of KIR AA genotype show lower reproductive success than KIR BX, due to the lack of activation of these immune cells. Additionally, another gene, HLA-F, expressed in endometrial cells, also seems to be involved in the recruitment and supplementary activation of uNKs. Certain alleles of this gene appear to decrease its expression in the uterus and hinder the processes in which it is involved during the decidualization process, decreasing implantation rates and increasing time-to-pregnancy. Study design, size, duration We conducted a prospective cohort study with 75 patients, with no history of recurrent miscarriage or implantation failure, who attended our institution to undergo assisted reproduction treatments (ART) with donated oocytes, between January 2021 and December 2022. By using the egg donation model, we were able to investigate the endometrial cell population avoiding the oocyte factor bias Participants/materials, setting, methods All patients included were under 45 years of age (40.5 ± 2.9 years), had a normal BMI (21.6 ± 1.9 kg/m2) and had not been diagnosed with uterine pathologies or immunological conditions. All recipients were genotyped for the KIR and HLA-F genes and pregnancy, miscarriage (MR) and live birth rates (LBR) obtained in their egg donation cycles were recorded. Fisher's test was used to determine statistically significant differences (p < 0.05) between groups Main results and the role of chance Patients were divided into two groups according to their KIR genotype: 29 KIR AA (inhibitor) and 46 KIR BX (activator). In each group, allelic load was determined for the three HLA-F regions studied (RS1362126, RS2523405 and RS2523393). For all these regions, patients with favorable HLA-F alleles and KIR BX genotype had higher pregnancy rates than KIR AA patients with unfavorable HLA-F alleles (85.42 % vs 54.17% for RS1362126 region, OR = 4.956, p = 0.008; 83.33% vs 58.62% for RS2523405 region, OR = 3.529, p = 0.0295; 82.5% vs 57.69% for RS2523393 region, OR = 3.457, p = 0.0462). No significant differences were obtained for MR or LBR. This demonstrates the involvement of KIR and HLA-F in embryo implantation and that the coincidence of unfavorable alleles for both decreases reproductive success considerably, probably due to impaired decidualization and lack of uNK recruitment and activation. No significant differences were obtained for the rest of the genetic profiles, except when comparing pregnancy rate of KIR AA women with favorable HLA-F alleles to KIR AA women with unfavorable HLA-F alleles for the RS1362126 region (79.41% vs 54.17%, OR = 3.264, p = 0.04). The latter finding suggests that the lack of uNK cell activation, so evident in KIR AA patients, could be compensated by expressing favorable HLA-F alleles. Limitations, reasons for caution The low sample size of this study does not allow us to compare groups taking into account other genes, such as embryonic HLA-C, which also, and in combination with KIR genotypes, has been shown to play a role in proper implantation and placentation. Wider implications of the findings uNKs activation is required to promote embryo implantation. Combination of unfavorable genetic profiles involved in these immune mechanism leads to lower pregnancy rate. The study of these genetic profiles can help to predict reproductive success, thus identifying patients susceptible to receive immunological treatment before embryo transfer, possibly decreasing their time-to-pregnancy. Trial registration number Not applicable

O-098 Improved pregnancy rates following day 5 eSET with early hatching/hatched blastocysts (116-118 hours) compared to expanded blastocysts in a strictly selected cohort: a prospective study

Abstract Study question To investigate whether blastocysts hatching early on day 5 following IVF are developmentally superior and lead to better clinical outcomes in non PGT-A eSET cycles. Summary answer Fresh eSET on day 5 with spontaneously early hatching blastocysts (116-118 hrs) results in significantly better pregnancy rates compared to top quality expanded blastocyst transfers. What is known already Most studies seem to indicate that transfer of blastocysts at more advanced stages of development result in higher pregnancy rates. However, most studies comparing results between full/expanded vs hatching/hatched blastocyst transfers are either retrospective, have relaxed inclusion criteria, or perform transfers following assisted hatching or extended culture. Moreover, there appears to be no data on proportion of blastocysts that spontaneously hatch early on day 5, or how well they perform comparatively. Yet it has been reported that earlier time-points of blastocyst development are associated with higher euploidy. We felt the need for a well-designed prospective study to address these questions. Study design, size, duration This prospective study to compare pregnancy rates between early hatching/hatched blastocysts and top quality expanded blastocysts (4 BB or higher) in fresh, non PGT-A eSET cycles took place between October 2021 and October 2022 following institutional ethical clearance. 115 patients<37 years with AMH>1.5 undergoing 1st IVF cycles for tubal, mild male factor, unexplained infertility consented for the study and 94 patients completed it to eSET. Patients with PCOS, endometriosis or previous pelvic surgery were excluded. Participants/materials, setting, methods The study was conducted at a tertiary IVF centre. All patients underwent antagonist cycles, egg retrievals and IVF as per standard protocol. Blastocyst culture decision was taken at 2-PN examination. Embryos were examined at 116-118 hours as per our practise and decisions made to exclude from data analysis patients without at least one blastocyst at 4BB or above. eSETs performed at 120-122 hours with hatching/hatched blastocysts where available, expanded blastocysts in others. Luteal support initiated. Main results and the role of chance Demographic parameters of the patient cohort such as age (30.79±4.06), BMI (25.53±3.11) and AMH (3.23±1.68) are presented as mean± SD. Data was analysed using IBM SPSS V.26 statistical package. Differences in pregnancy rates between early hatching/hatched vs expanded blastocyst eSET groups were tested using Z test for proportions at 5% level of significance. Data was analysed for 94 patients of whom 62 had single expanded blastocyst transfers (22 achieved pregnancies) and 32 had eSET with early hatching/hatched blastocysts (of whom 18 became pregnant). 55 out of a total 261 blastocysts in the whole cohort were found to have initiated spontaneous hatching (n = 39) or fully hatched (n = 16) at 116-118 hours post-fertilisation resulting in an early hatching rate of 21.1% per blastocyst. Clinical pregnancy rate (CPR) defined as fetal heartbeat on ultrasound at 6 weeks of gestation and ongoing pregnancy rate (OPR) defined as pregnancy continuing beyond 10 weeks were found to be significantly superior in early hatching/hatched group vs expanded blastocyst group (CPR: 56.3% vs 35.5%, p = 0.002; OPR: 50% vs 30.6%, p = 0.003). Difference between miscarriage rate in the hatching/hatched group (11.1%, n = 2) and expanded blastocyst group (13.6%, n = 3) was not statistically significant. Limitations, reasons for caution Our sample size was relatively small in order to rigorously select a homogeneous group of good prognosis patients and adhere to strict study criteria- only 1st cycle, autologous, fresh, non PGT-A, day 5 eSET cycles were included. Larger controlled prospective studies would be valuable to confirm these findings. Wider implications of the findings To our knowledge this is the first report of improved pregnancy rates with early hatching blastocyst eSETs compared with expanded blastocysts. Basic science studies may shed more light on the biological underpinnings of these findings. Such transfer strategy may also prove useful to select the best blastocysts in non-PGT-A cycles. Trial registration number not applicable

P-533 Comparison of Endometrial Receptivity Array (ERA) with Preimplantation genetic testing (PGT) versus ERA alone in improving outcomes in Recurrent implantation failure.

Abstract Study question Whether addition of Preimplantation Genetic Testing for aneuploidy (PGT-A) to Endometrial Receptivity Array (ERA) helps in improving success rates in Recurrent Implantation Failure (RIF) patients. Summary answer Addition of PGT-A intervention to ERA in RIF patients did not improve outcomes. What is known already RIF causes great emotional stress and financial burden for the infertile couple. Successful implantation requires a synchronous interaction between a competent blastocyst and a receptive endometrium. Though ERA, as a measure to assess window of implantation (WOI), is around a decade old, its role in improving success rates in patients with RIF is still controversial. PGT-A, as a tool for selecting euploid embryos, though has shown to be beneficial in women with advanced maternal age, its role in improving success rates in RIF needs further evaluation. Study design, size, duration This is a multicenter retrospective cohort study carried out from September 2015 till September 2022. 285 patients with RIF with previous failed transfers with ≥ 3 good quality embryos were included. Participants/materials, setting, methods 285 patients with RIF were divided into 2 groups. Group 1 underwent PGT-A and Personalised Embryo Transfer (pET) guided by ERA and Group 2 underwent only ERA followed by pET. In Group 1 patients, embryo biopsy was done on day 5 and day 6 blastocyst before cryopreservation and NGS platform was used to detect euploid embryos. Both groups then underwent ERA followed by pET in the next cycle. Main results and the role of chance In total of 285 RIF patients studied, 59.2% patients showed displaced WOI. 91.7% ERA reports were pre-receptive. Group 1 included 137 patients and Group 2 had 148 patients & baseline characteristics were similar in both the groups. Group 1 had more self transfer cycles, i.e. 76.7% self and 17.2% donor oocytes, as compared to Group 2 with 40.2% self and 30.7% donor oocyte cycles. The implantation rate (IR), live birth rate (LBR), miscarriage rate and cumulative LBR were similar in both the groups. Higher Pregnancy rate (PR) in Group 2 (70.9% vs 57.83%) could be attributed to higher donor cycles in this group. Multiple gestation rate was also higher in Group 2 (31.49% vs 11.21%) as 2 blastocysts were transferred in most cycles in group 2 compared to Single embryo transfer(SET) in most cycles in Group 1. As PR was higher in ERA group, subgroup analysis of self gamete transfers and donor oocyte transfers was also done, which showed similar PR, IR and LBR in both the groups. Hence, PGT failed to show any value in improving pregnancy outcomes in RIF. Limitations, reasons for caution Retrospective study design. Wider implications of the findings The role of PGT in improving clinical outcomes in RIF patients needs to be studied in larger prospective studies. In our study, ERA as an intervention improved outcomes in RIF. Trial registration number not applicable

P-580 Virtual reality as tool to reduce anxiety during embryo transfer.

Abstract Study question Is the use of virtual reality during embryo transfer effective as a measure to reduce anxiety during the procedure? Summary answer With the current evidence, it cannot be affirmed that virtual reality is useful as a tool to reduce anxiety during embryo transfer. What is known already The embryo transfer (ET), the last and crucial procedure of in vitro fertilization (IVF), generates anxiety, especially in couples with a history of reproductive failure. The latest evidence suggests that a high level of stress can influence reproductive results. Virtual reality (VR) seems to be a useful tool that helps to relieve pain, stress, anxiety and depression symptoms. VR has recently been proposed as a method to alleviate pain and emotional impact in other gynecological procedures such as hysteroscopy. It would be interesting to study the potential beneficial impact of the application of virtual reality to reduce anxiety during ET. Study design, size, duration This is an experimental and ramdomized study. A total of 128 infertile women undergoing ET were included, who were grouped into two groups based on whether or not they used VR glasses. In all of them, the level of anxiety was assessed according to validated questionnaires (STAI and GAD-7) along with other clinical parameters such as pain (VAS) or blood pressure. The recruitment period was from May to June 2022. Participants/materials, setting, methods 128 women between the ages of 18 and 40 who underwent vitrified or fresh embryo transfer were included. Patients under treatment with antidepressants or anxiolytics, drug users, or neurosensory deficits were excluded. In the experimental group, the usual ET procedure was performed applying VR (virtual reality class 1 medical device developed by Deepsen and Metronic®). The study was carried out in the Assisted Human Reproduction Unit of the Virgen de Valme University Hospital (Seville). Main results and the role of chance The 128 participants were randomized into two groups, 64 in each study arm: experimental group (exposed to VR) and control group (normal ET procedure). The characteristics of the patients were comparable between the two groups. Systolic blood pressure (120.62 ± 15.11 vs 126.04 ± 12.26), diastolic blood pressure (75.41 ± 9.58 vs 81.28 ± 9.28) and mean blood pressure (90. 14 ± 10.97 vs 95.54 ± 9.79) after embryo transfer were significantly (p < 0.05) lower in the experimental group compared to the control group. However, no differences were observed between the two groups in pain (VAS), blood pressure before the procedure, respiratory rate and oxygen saturation before and after ET. Anxiety level scores (STAI and GAD-7) were comparable between the two groups. Unlike the only comparable study in which a higher pregnancy rate was observed in the experimental group (although without statistical significance), in our study the pregnancy rate was higher in the control group (33.3% vs 43.8%). However, in our study the gestation rate that exceeded 6 weeks of pregnancy was higher in the experimental group (81% vs 71.4%), although without statistical significance. Limitations, reasons for caution The sample size is too small, making it difficult to find significant relationships. In addition, there are no previous studies that support the theory of the study. Wider implications of the findings There is only one previous comparable study evaluating the use of VR in assisted reproduction. Our findings suggest changes in blood pressure with the use of VR, although this is not the case in the rest of the parameters analyzed. A larger sample is needed to confirm these findings. Trial registration number Not applicable

P-792 The effect of subendometrial injection of autologous platelet rich plasma (PRP) guided by hysteroscopy in recurrent implantation failure patients - A pilot study

Abstract Study question Does the subendometrial injection of autologous platelet-rich plasma (PRP) guided by hysteroscopy achieve successful pregnancy outcome in recurrent implantation failure patients? Summary answer In this study we observed that subendometrial injection of autologous PRP is associated with higher implantation rates in recurrent implantation failure patients. What is known already The key success factors in IVF are to have a good endometrium lining and vascularity for successful implantation. These two factors directly affect the pregnancy outcomes of IVF. Although several approaches have been attempted to address these factors including estrogen treatment, aspirin, sildenafil, vitamin E, Granulocyte-Colony Stimulating Factor (G-CSF), there is no efficient method described. Additionally, some cases do not show a response to the medical treatment. In those cases, specifically, in previously failed IVF patients autologous Platelet Rich Plasma (PRP) injection into the sub-endometrial cavity with an ovum pick up needle has been preferred, as confirmed by literature. Study design, size, duration An open label, single center study. Total 130 women were selected for hysteroscopic instillation of PRP, all patients have previous unsuccessful IVF attempts in our clinic or were referred to our clinic. Study participants are of age 23 to 49 years. Study began in July 2020 and was completed in December 2022. Participants/materials, setting, methods 2 ml of autologous PRP was instilled in the junctional zone using a wallace needle through the hysteroscope's operating channel to inject the PRP beneath the superficial endometrium from day 6-14 of menstrual cycle. FET preparation was started from Day 2/3 of next menstrual cycle using 6 mg/daily estradiol hemihydrate (EV Active Tab CORONA Remedies). Main results and the role of chance Women who received hysteroscopic instillation of PRP in the sub-endometrial junction had higher pregnancy rates (82/130 [63.07%] (P-value = <0.05). In the subsequent cycle monitored to day 15, Endometrial thickness (ET) was 7 mm or thicker in 90 of 130 patients [69.23%] (P-value = <0.05) and 6-7 mm in 8 of 130 patients [6.15%]. Endometrial thickness did not improve in 32 of 130 patients [24.61%] and remained below 6 mm. Subendometrial blood flow increased significantly in 92 of 130 patients [70.76%] (P-value = <0.05). The mean increase in ET was 1.5 to 2 mm. The instillation of PRP caused no side effects and was well tolerated by all patients. In 47 patients (36.15%) we did not achieve clinical pregnancy while 1 had a biochemical pregnancy Based on paired ‘t’ test, it is concluded that there is statistically significant improvement in ET, vascularity and successful pregnancy outcome after PRP instillation. Limitations, reasons for caution Little is known about the best dosage and time for the instillation of PRP in endometrium. The importance of standard yet simple techniques and a highly repeatable protocol for clinical use is deciding factor which yet to finalize. It involves invasive procedure so may cause infections and anesthesia related complications. Wider implications of the findings Although PRP has still not gained universal acceptance in previously failed IVF patients for a variety of reasons, emerging evidences suggests that PRP could be an effective option compared to conventional approach especially, in patients with thin endometrium, advanced maternal age and primary ovarian insufficiency. Trial registration number Not applicable

P-357 Downregulation (DR) with combined gonadotropin-releasing hormone agonist (GnRHa) and aromatase inhibitor (AI) optimizes the frozen-thawed embryo transfer (FET) results in women with adenomyosis

Abstract Study question Does combined GnRHa & AI therapy for downregulation in women with adenomyosis optimize the FET success rates / outcomes on par with women without adenomyosis? Summary answer GnRHa combined with AI used for downregulation in women with adenomyosis optimized the outcomes of frozen–thawed embryo transfer cycle on par with women without adenomyosis. What is known already Women with adenomyosis have lower rates of successful implantation via altered molecular expressions in the endometrium due to local hyperestrogenism & also an increased risk of early pregnancy loss (Munro et al 2019). DR improves the clinical pregnancy rate by reducing the endometrial inflammatory reaction and/or myometrial contractility and their impact on uterine receptivity in women with adenomyosis undergoing FET (Sania Latif et al 2021). Combined treatment for uterine adenomyosis with Anastrazole plus GnRHa showed better results than dienogest treatment with a higher reduction of symptoms & higher pregnancy rates (M Sbracia & F Scarpellini, 2018). Study design, size, duration A Retrospective cohort study conducted at a tertiary care fertility unit. Data for 326 women with/without adenomyosis undergoing frozen–thawed embryo transfer after IVF was was retrieved from the hospital's database and analyzed for a period between September 2021 to November 2022. Participants/materials, setting, methods Women with adenomyosis (n = 107) received Anastrozole 1mg/day for 2months plus 3doses of Inj. Goserelin 3.6mg subcutaneously at 28days interval between 2successive doses. Hormone replacement therapy (HRT) was started 2weeks after the 3rddose of Inj. Goserelin & FET was performed after an optimum endometrial thickness (EMT) was achieved. For women without adenomyosis (n = 219) HRT was started on cycle Day-2 & FET was performed after achieving an optimum EMT. Serum beta-hCG was performed on Day15 after FET. Main results and the role of chance Statistical analysis was performed using SPSS20version. Normally distributed continuous variables were compared using a student t-test, and categorical variables were compared by χ2 and Fisher's exact test, where appropriate. To reduce selection bias, propensity score matching was used, and propensity matching yielded 99 pairs. Baseline characters like age (p-value=0.36), BMI (p-value=0.12), duration (p-value=0.28), type (p-value=1) & cause (p-value=0.3) of infertility, endometrial thickness (p-value=0.37), day of embryo transfer (p-value=0.57) were comparable for the two groups. FET results in terms of positive pregnancy test (Serum beta-hCG > 50mIU/ml) were found to be 68.21% for the DR- FET group and 67.71% for the HRT group which were comparable(p-value=0.17). This suggests that downregulation in women with adenomyosis helps achieve success rates similar to women without the disease. Pregnancy outcomes like miscarriage (15 vs 13.13 %, p-value=1.00), biochemical pregnancy (3.03 vs 2.02 %, p-value=1.00) and ectopic pregnancy (1.01 vs 0 %, p-value=0.49) rates analyzed between the DR FET and HRT groups showed no statistically significant difference. Clinical pregnancy rates were almost similar for the 2 groups (55.71 Vs 57.46%, p-value=0.65). Thus, we conclude that downregulation with combined GnRHa and AI optimizes the frozen-thawed embryo transfer results in women with adenomyosis on par with women without adenomyosis. Limitations, reasons for caution This is a retrospective study and hence randomized comparison was not possible. Women were followed up for 12 weeks of pregnancy, hence live birth rates were not analyzed in our study. Wider implications of the findings Combining the two treatment modalities (GnRHa + AI) which work at different sites optimizes IVF success rates & pregnancy outcomes. Hence we suggest that well-designed prospective randomized studies are needed to further analyze the synergistic role of this drug combination for downregulation in women with varied severity of adenomyosis. Trial registration number Not applicable

O-258 Characterization of vaginal microbiota during IVF fresh embryo transfer (IVF-ET) and in early pregnancy

Abstract Study question Does the composition of vaginal microbiota affect the success of IVF-ET? Does vaginal microbiota profile change intra-individually from IVF-ET to early pregnancy? Summary answer L. crispatus is associated with successful IVF outcome. The individual composition of vaginal microbiota tends to shift towards Lactobacillus-dominance between IVF-ET and early pregnancy. What is known already Lactobacilli are the most abundant species in healthy female reproductive tract microbiota and especially Lactobacillus crispatus is associated with good gynecological health. The composition of vaginal microbiota may also play an important role in infertility and the success of IVF. Women with Lactobacillus-dominated vaginal microbiota may have higher pregnancy rates after IVF-ET compared to women with non-Lactobacillus dominance, but the results have been controversial. In healthy pregnancy, vaginal microbiota is usually lactobacilli-dominated, whereas miscarriages are associated to a non-lactobacillus dominance. The intra-individual shift on the vaginal microbiota from ET to early pregnancy has not been studied earlier. Study design, size, duration This observational and longitudinal study investigates the effect of vaginal microbiota on the success of fresh IVF-ET. Another aim was to study the intra-individual changes in the microbiota profile between IVF-ET and early pregnancy. We recruited 76 subfertile women undergoing IVF with their own gametes between November 2019 and September 2021 in the Reproductive Medicine Unit, Helsinki University Hospital and in Oulu University Hospital. Main outcomes were clinical pregnancy and live birth. Participants/materials, setting, methods Study population composed of 76 subfertile women under 40 years of age. One IVF cycle including fresh embryo transfer was studied. Vaginal swabs were taken at the time of IVF-ET and at 8th gestational week. Samples were frozen in − 20 °C and moved to − 80 °C within four weeks. Microbiota analysis was performed with next-generation sequencing of 16S rRNA gene using Illumina MiSeq technology. Clinical data were collected from the patient registries and background questionnaires. Main results and the role of chance Altogether 30 (39.5%) of the 76 women achieved pregnancy after IVF-ET and 26 (34.2%) had live birth. The relative abundance of L. crispatus among women who achieved clinical pregnancy (46.9% vs. 19.1%, q = 0.003) and live birth (43.3% vs. 19.1%, q = 0.006) was significantly higher compared to women who did not. After adjusting for age, parity and gravidity, the results remained similar when comparing clinical pregnancy (q = 0.039), but in live birth, the difference lost significance (q = 0.14) Vaginal samples were taken at the 8th gestational week from 21 of 30 women who got pregnant. All samples were dominated by Lactobacillus species, mainly by L. crispatus (n = 16, 76.2%). Only two (9.2%) women had L. iners dominated microbiota at the early pregnancy. When comparing samples taken during fresh IVF-ET and early pregnancy, L. crispatus had significantly higher relative abundance in early pregnancy samples compared to the samples taken at the ET (71.5% vs. 43.4%, q = 0.001), whereas the relative abundance of L. iners (10.1% vs. 24.1%, q = 0.004), and G. vaginalis (0.8% vs. 14.7%, q = 0.004) decreased. Altogether 13 women had an intra-individual shift in their microbiota profiles. Limitations, reasons for caution The small sample size was the main limitation of our study. Larger studies are needed to confirm our findings and their relationship with the success of IVF-ET. Wider implications of the findings Vaginal microbiota at the time of fresh IVF-ET has an impact of the success of IVF treatment. Also, the intra-individual composition of vaginal microbiota between IVF-ET and early pregnancy changes in some women. The vaginal microbiota modification through probiotics in order to optimize the result of IVF warrants more studies. Trial registration number Not applicable

P-212 βhCG concentration in peripherical maternal blood after single embryo transfer, ongoing pregnancy rates and morphokinetics

Abstract Study question Is there a relationship between the concentration of the βhCG hormone in maternal blood, embryo morphokinetics and clinical outcome? Summary answer βhCG concentration is related to trophoectoderm quality, abortion rate and live birth rate, but not to embryo morphokinetics What is known already Measurement of βhCG has been widely used for early pregnancy detection after assisted reproduction treatments. Shortly after embryo implantation, trophoblastic βhCG is detectable in maternal blood, However, βhCG concentration in several women showed high variability, and embryo implantation also depends on endometrial receptivity, what means that in early stages, everything affecting endometrial receptivity, may affect βhCG concentration. Early high βhCG concentration has been related with higher pregnancy rate, but there are scarce information concerning relationship between βhCG early value and ongoing pregnancy rates Study design, size, duration Retrospective biomedical research of 508 patients having single embryo transfer of fresh embryos at IVIRMA VIGO clinic between 2017 and 2021 to analyse the relation between βhCG concentration, and embryo quality, embryo morphokinetics and ongoing pregnancy rate. Patients with recurrent miscarriage, advanced maternal age, uterine pathologies and severe male factor were excluded of the study. βhCG was measured in the peripherical maternal blood 13 days after embryo transfer Participants/materials, setting, methods All the embryos were generated by ICSI and were cultured in a time-lapse incubator under a 37ºC, 6% CO2 and 5% O2 atmosphere. T-Student and Youden test between embryo kinetics and βhCG values, Pearson correlation test to compare gestational successes with kinetic embryo data, and a linear regression model with βhCG like response variable and morphokinetic data like explanation variables were employed Main results and the role of chance βhCG concentration was greater in trophoectoderm A embryos compared to B and C (ASEBIR classification), 619.53 UI/ml, IC95% (483.16-755.90), 442.24 UI/ml, IC95% (350.18-534.31), 269.95 UI/ml, IC95%(88.88-451.01) (p = 0.038) respectively and there was a trend with Inner cell mass quality, being greater also in quality A vs B and C (p = 0.053) Patients who had a clinic abortion showed lower βhCG concentration compared to those with ongoing pregnancy and live birth, 385.37 UI/ml, IC95% (268.45-502.28) vs 987.53 IU/ml, IC95% (845.03-1130.03). T-student test linear regression analysis and Youden index, with βhCG cut-off points of 10 IU/ml and 100 IU/ml were employed, to analyze relationship between βhCG concentration and embryo morphokinetics, but it was not significant in any of the parameters analyzed Limitations, reasons for caution There is a limited sample size and data were obtained from a retrospective study. Patients and donor oocytes were analyzed in this study, although no differences were found when they compared Wider implications of the findings This study shows that a top quality trophoectoderm produces more βhCG, and that could be a predictive value for ongoing pregnancy Trial registration number 1712-VGO-122-EM

P-542 How should we prepare the endometrium in euploid embryo transfer cycles? Modified natural or artificial endometrial preparation?

Abstract Study question Does modified natural endometrial preparation in single euploid frozen-thawed embryo transfer (FET) cycles affect chance of pregnancy and risk of miscarriage compared to artificial? Summary answer The rate of clinical pregnancy and live birth increases while the rate of miscarriage decreases in modified natural FET cycles compared to artificial FET cycles. What is known already Corpus luteum produces growth factors, angiogenic factors and vasoactive substances as well as hormones. These substances play role for initial placentation. Early maternal endocrine milieu resulting exogenous estrogen and progesterone could damage placentation, which may in turn cause miscarriage. High estradiol levels might also be responsible for decreased pregnancy rates (Wu et al 2021). Study design, size, duration This retrospective, single center study evaluated 1890 frozen single euploid embryo transfer cycles in women between 20-43 years old from January 2017 to September 2021. The study is based on data obtained from Istanbul Memorial Hospital, ART and Reproductive Genetics Center. FET cycles were analyzed in two groups according to different endometrial preparation protocol. Group A (n = 1335): modified natural FET cycles (mNat/FET) and Group B (n = 555): artificial FET cycles (AC-FET). Participants/materials, setting, methods Only good prognosis patients with ages between 20-43 years old were included. Exclusion criterias were women age 44 and above, recurrent abortion history, BMI>35 kg/m 2, endometrial factor, uterin factor (adenomyosis, mullerian anomaly) history. NGS was used to study trophoectoderm biopsy material in all cases. Patients demographics, cycle characteristics and pregnancy outcomes were analyzed. Main results and the role of chance We analyzed the effect of endometrial preparation methods on pregnancy outcomes between the two groups after excluding confounding factors in single euploid embryo transfer cycles. There were no significant differences in patient demographics and cycle characteristics such as age, body-mass index, infertility duration, previous IVF attempts, AMH level, daily gonadotropin dosage used, number of oocytes obtained, mature oocytes and fertilized oocytes between the two groups. There was no significant difference between the morphologic grading of the transferred embryos in both groups. However, all pregnancy outcomes were statistically significantly different in two groups. In group A, biochemical pregnancy rate (76.9% vs. 73.9%, p:0.04), clinical pregnancy rate (71% vs. 65.7%, p < 0.01), live birth rate (65.4% vs. 50.5%, p < 0.01) were significantly higher than in group B. Also, biochemical pregnancy loss rate (7.7% vs. 11%, p:0.01), clinical pregnancy loss rate (6.7% vs. 21%, p < 0.01), second trimester pregnancy loss rate (0.8% vs. 1.5%, p:0.04) were significantly lower compared to group B. Limitations, reasons for caution The limitation of our study include the fact that this was a retrospective analysis. Prospective randomised studies are necessary to evaluate the differences between the two groups according to pregnancy outcomes. Wider implications of the findings This study shows that pregnancy outcomes are better in patients undergoing mNat/FET even after controlling for confounding factors when comparing mNat/FET and AC-FET in single euploid FET cycles. As a result, in appropriate patients, mNat/FET with higher pregnancy rate and live birth rate should be preferred as much as feasible. Trial registration number Not applicable

Learners' perspectives on the prevention and management of pregnancy school dropout: a Namibian case.

Namibia has had a problem with the high rate of learner pregnancy and school dropout for many years, despite implementing education sector policy on preventing and managing learner pregnancy. This study aimed to explore the perspectives of school-going learners in Namibia regarding the factors contributing to learner pregnancy and school dropout and propose interventions to address them. This qualitative research employed interpretative phenomenological data analysis, with seventeen individual and ten focus group interviews involving 63 school-going learners: adolescents, pregnant learners, and learner parents. Emerging factors driving learner pregnancy and school dropout in rural Namibian schools include older men and cattle herders preying on young girls, long school holidays, the proximity of alcohol sites near school premises, and age restrictions after maternity leave. The learners proposed interventions include prohibiting learners' access to alcohol establishments, strengthening collaborations between stakeholders, sensitizing girls and cattle herders, and ongoing advocacy efforts. Findings indicate community hostility, lack of infrastructure and resources, and learner unawareness. It is essential to mitigate community hostility and raise awareness. Incorporating the perspectives of learners in policy interventions remains crucial for effectively addressing the high rates of learner pregnancy and school dropout in rural Namibian schools.