P-589 Natural endometrial preparation for single euploid frozen embryo transfer increases the likelihood of live birth in obese patients

Study question

Does a natural endometrial preparation for single euploid frozen embryo transfer increase the odds of live birth (LB) in obese patients?

Summary answer

Compared to an artificial approach, a natural endometrial preparation for single euploid frozen embryo transfer improves the odds of LB in obese patients.

What is known already

Several protocols to prepare the endometrium for frozen embryo transfer have been described with comparable clinical outcomes, and no individual protocol has been demonstrated to be superior. Likewise, no specific patient group has been defined that can substantially benefit from a natural endometrial preparation. Despite obesity being linked to adverse clinical outcomes, observational studies and clinical trials have traditionally included participants with normal weight when comparing protocols, resulting in obese patients being underrepresented in clinical research. Therefore, studies focusing on endometrial preparation protocols for frozen embryo transfer that include obese patients are required.

Study design, size, duration

This study involved the analysis of a retrospective dataset including 975 single euploid frozen embryo transfer cycles performed at two tertiary referral centers between March 2017 and November 2019. The primary outcome was LB after natural and artificial endometrial preparation. Participants were stratified according to the World Health Organization Body mass index (BMI) classification into three groups (G): G1: Normal-weight ≤24.9 (n = 390), G2: Overweight 25 to 29.9 (n = 332), and G3: Obese ≥30 (n = 253).

Participants/materials, setting, methods

Cycles included infertility patients attempting a single euploid frozen blastocyst transfer under natural (n = 324) or artificial (n = 651) endometrial preparation. PGT-A was performed after trophectoderm biopsy using Next-Generation Sequencing. Spontaneous LH rise confirmed ovulation for natural endometrial preparation, and embryo transfer occurred five days after initial progesterone elevation. Hormones were measured from blood samples. For artificial preparation, embryo transfer was performed after oral estradiol and 120-hour vaginal progesterone exposure. All participants received luteal phase support.

Main results and the role of chance

Within each BMI group, no statistically significant differences in age were observed in patients between a natural and artificial endometrial preparation: G1 (33.5±5.1 vs. 32.7±5.2 years; p = 0.13), G2 (34.5±4.9 vs. 33.9±5.8 years; p = 0.39), and G3 (35.6±4.9 vs. 34.3±5.6 years; p = 0.1). Similarly, no statistically significant differences were observed regarding implantation rates: G1 (60% vs 57.1%; p = 0.57), G2 (54.8% vs 55.7%; p = 0.88), and G3 (64.3% vs 51.4%; p = 0.07). LB rates remained constant across all BMI groups when a natural preparation was conducted: G1 [56.66% (n = 85/150)], G2 [49.03% (n = 51/104)], and G3 [58.57% (n = 41/70)]. We observed a decrease in LB rates in G3 when an artificial endometrial preparation was performed: G1 [47.5% (n = 114/240)], G2 [44.73% (n = 102/228)], and G3 [34.42% (n = 63/183)]. The positive impact of a natural preparation on LB rates was more significant in G3, showing a 24% difference of effect between the natural and artificial endometrial preparations. Univariate logistic regression analysis showed a statistically significant difference in the primary outcome (LB) when a natural endometrial preparation was conducted in G3 (OR 2.69, 95% CI 1.53-4.74; p = 0.001), with no differences found in G1 (OR 1.45, 95% CI 0.96-2.18; p = 0.08) and G2 (OR 1.19, 95% CI 0.75-1.89; p = 0.73).

Limitations, reasons for caution

This study could be subject to bias due to its retrospective nature. Sperm quality was not considered for the present study.

Wider implications of the findings

Obese women appear to be the patient group that can obtain benefit from a natural endometrial preparation for frozen embryo transfer by increasing the odds of LB. Future prospective studies should confirm this hypothesis. A natural approach might be unfeasible in a subgroup of obese patients due to anovulatory cycles.

Trial registration number

not applicable

P-377 Does C-Section history affect the live birth outcomes after IVF in case of frozen embryo transfers?

Study question

Do previous Caesarean section deliveries (CD) affect reproductive outcomes in case of frozen embryo transfers (FET), including live births (LB), after IVF or ICSI?

Summary answer

Previous CD does not impair LBR after IVF when cycle segmentation is performed and intracavitary fluid (ICF) is eliminated prior frozen embryo transfer.

What is known already

Successful implantation requires not only a receptive endometrium, but also the process of ‘apposition’ and ‘attachment’ of the embryo to the endometrial surface. This process could be severely disturbed by previous CD and data are contradictory regarding its impact on ART outcome. Former CD might not only increase the difficulty of the ET-procedure, but might also lead to the presence of ICF. Therefore, special attention has to be paid to exclude fluid accumulation during preparation for FET. When ICF is excluded, the reproductive outcomes of FET cycles appear to be uncompromised, regardless of the previous delivery mode.

Study design, size, duration

This single center retrospective cohort study included a total of 412 single/double euploid FET cycles between March 2017 and October 2019. Trophectoderm biopsy samples were subjected to Next Generation Sequencing to diagnose the ploidy state. Vitrification and warming were performed using the Cryotop method (Kitazato, Biopharma). No embryo transfer was performed when ICF was visible during the endometrial preparation for FET.

Participants/materials, setting, methods

Patients with secondary infertility, having at least one euploid embryo after a previous IVF/ICSI-cycle with embryo vitrification, undergoing FET, were included. Clinical pregnancy rate (CPR), early pregnancy loss (EPL) and LBR were evaluated in patients after CD and after vaginal delivery (VD).

Main results and the role of chance

Patients in the CD group were significantly older than in the VD group (35.02±4.62 vs 34.11±5.03 years, respectively) (p = 0.028). FET was performed in a Natural cycle (NC) (n = 82, 46.86%) or in a Hormonal replacement therapy (HRT) cycle (n = 93, 53.14%) in CD group versus NC (n = 77, 32.49%) or HRT cycle (n = 160, 67.51%) in VD group (p = 0.003).

Patient characteristics (AMH, BMI, duration of infertility, presence of intrauterine abnormalities, endometrial thickness, embryo quality, presence of blood on the transfer catheter and number of SETs/DETs) were similar between groups. Embryo transfer difficulty and the presence of mucus on the transfer catheter were significantly higher in CD group versus VD group (p = 0.040, p=0.004, respectively). Pregnancy outcomes CPR (61.71% vs 63.71%), EPL (12% vs 12%) and LBR (60% vs 60.34%) did not differ statistically between the CD and VD groups.

In the multivariate regression model with embryo-quality, cycle-regimen, ET-difficulty, presence of blood/mucus, age, AMH, number of transferred embryos, only embryo quality remained significantly associated with LBR in CD-group (p = 0.001). In VD-group, cycle regimen was also significant parameter besides embryo quality (p = 0.001, p = 0.001 respectively). When CD and VD groups are categorized in terms of cycle regimen, CP and LBR were similar (p = 0.828/p=0.618 in HRT; p = 0.826/p=0.150 in NC).

Limitations, reasons for caution

This study is limited to its retrospective design and the fact that no distinction existed between patients with one or several previous CDs. Furthermore, this analysis is limited to patients, for whom ICF was excluded prior to ET.

Wider implications of the findings

This study confirmed that in patients after CD, the chance for CP and LBR is not compromised, when ICF is excluded during the endometrial preparation for FET. The existence of C-section scar may increase the ET-difficulty and the presence of the mucus on the transfer catheter.

Trial registration number

NA

P-358 Effect of endometrial thickness on biochemical pregnancy rate: an analysis of 1534 frozen euploid embryo transfers

Study question

Can a thick endometrial lining measured prior to embryo transfer be considered a protective factor against Biochemical Pregnancy (BP)?

Summary answer

The risk of BP is independent of Endometrial Thickness (EMT), but rather dependent of the type of endometrial preparation and parity.

What is known already

Higher EMT prior to embryo transfer is associated with better clinical outcomes in general, like higher implantation and livebirth, and lower miscarriage rates. But up to our knowledge, no studies evaluated the effect of EMT on BP per say.

Study design, size, duration

This is a two-center retrospective observational study including a total of 1534 euploid Frozen Embryo Transfer (FET) cycles between March 2017 and March 2020 at ART Fertility Clinics Muscat, Oman and Abu Dhabi, UAE. BP is defined as blood beta-hCG >15 mIU/ml on day 12 post FET, that is progressively decreasing, with no evidence of gestational sac on ultrasound.

Participants/materials, setting, methods

The study group consisted of 112 cases of BP, while the control group consisted of the remaining 1422 FET’s that led to different clinical outcomes. EMT was measured by transvaginal ultrasound on the day of progesterone rise (±1 day); that rise was either spontaneous in Natural Cycles (NC), or iatrogenic in Hormone Replacement Therapy (HRT) cycles. Euploidy status of the embryos was assessed by NGS analysis of trophectoderm biopsies. Bivariate and multivariate analyses were conducted.

Main results and the role of chance

There was no difference in mean EMT between the study and the control groups (7.55 vs. 7.68 mm, p = 0.154).

Looking at the association of different variables with the rate of BP, there was no effect of age, BMI, AMH, number of embryos transferred, degree of blastocyst expansion, inner cell mass or trophectoderm grade, day of biopsy, nor presence of blood or mucus on the transfer catheter. However, patients on HRT cycles had significantly higher rates of BP compared to NC (8.42% vs. 4.99%, p = 0.015). Also, those with a previous livebirth had higher rates of BP compared to nulliparous women (8.7% vs. 5.39%, p = 0.014).

The distribution of BP showed that 54.5% occurred with EMT <7.5 mm, 34.8% with EMT 7.5-9 mm, and 10.7% with EMT >9 mm. These represents respectively 8.16%, 6.68%, and 5.94% of the total sample. This decreasing trend of BP with increasing EMT didn’t reach statistical significance (p = 0.429). Univariate analysis comparing the risk of BP in FET’s done with lower and higher EMT to those performed at 7.5-9 mm yielded similar conclusion: OR = 1.24 [0.82-1.88] for <7.5 mm, and OR = 0.88 [0.45-1.72] for >9 mm.

Controlling for different confounders, HRT cycles and multiparity remained as independent risk factors for BP.

Limitations, reasons for caution

Inter-observer variability in EMT measurement and the transfer technique, the retrospective nature of the study, and the lack of data on the mode of delivery of parous women could all have interfered with the conclusion.

Wider implications of the findings

The reduced adverse clinical outcomes with NC shed light on the role of the corpus luteum in the early phases of implantation, and some potential secreted mediators other than progesterone. Besides, the effect of previous deliveries on the endometrium and its receptivity needs further investigation.

Trial registration number

not applicable

P-201 Identifying patients benefiting from delayed-matured oocytes insemination

Study question

Are there any predictive factors supporting the decision of inseminating delayed-matured oocytes?

Summary answer

Patients with ≤59% mature oocytes at retrieval and/or Anti-Mullerian-Hormone (AMH) >2.52 ng/ml have increased chances of obtaining a euploid embryo from delayed-matured oocytes.

What is known already

Approximately 15% of oocytes retrieved after ovarian stimulation are immature, at metaphase I (MI) or germinal-vesicle (GV) stages at the time of oocyte denudation. Performing IVM in those oocytes could permit an increase on the number of usable embryos. Nevertheless, the utility of delayed-matured oocytes varies greatly among IVF laboratories with relatively low success rates, hence its practice in daily routine might be counter-productive. Determining which patient population could benefit from such strategy is valuable thereof to the clinical practice. Moreover, data comparing euploid rates of embryos derived from delayed-matured oocytes with its mature sibling oocytes are needed.

Study design, size, duration

This observational study was performed at ART Fertility Clinics, Abu Dhabi, UAE, between January 2019 and June 2021. A total of 5454 cumulus oocytes complexes (COC) were retrieved from 469 ovarian stimulation cycles. Out of the retrieved COCs, 3473 oocytes were immediate at metaphase II (MII-D0), and 915 were delayed-metaphase II oocytes (MII-D1).

Participants/materials, setting, methods

Patients with primary and secondary infertility undergoing Controlled ovarian stimulation (COS) in standardized protocols for IVF/ICSI treatment were included. Ovum pick up performed 34-36h post final oocyte maturation trigger shot (TS). Insemination was done 39-41h post TS for the MII-D0, while MII-D1 ICSI was performed 63-68h post TS. All cycles were planned for Preimplantation Genetic Testing for Aneuploidies (PGT-A) at blastocyst stage using Next Generation Sequencing (NGS).

Main results and the role of chance

Fertilization rates significantly differed between MII-D0 and MII-D1 oocytes (69.54% vs 55.96%, p < 0.001, respectively). Blastocyst utilization rates were significantly higher in MII-D0 group compared to MII-D1 group (59.47% vs 18.52%, p < 0.001). However, no difference was observed in the rate of euploid blastocysts between MII-D0 and MII-D1 (46.3% vs 39.0%, p = 0.163).

As identified by univariant logistic regression analysis, the following parameters augmented the chances of obtaining at least 1 blastocyst for biopsy when MII-D1 were injected: AMH (OR 1.15, p < 0.001), number of COCs collected (OR: 1.03, P = 0.005), maturation rate on day0 (OR: 0.19, P = 0.001).

When the multivariant analysis model was applied, AMH and maturation rate on day0 remained significant factors predicting the success of inseminating delayed-matured oocytes (OR:1.15, [CI:1.00-1.32], p = 0.045); OR:0.06, [CI:0.03-0.31], p < 0.001, respectively), with cut off values of AMH >2.52 ng/ml and maturity rate of ≤ 59%, being identified by ROC analysis.

Limitations, reasons for caution

ICSI of MII-D1 was performed with the fresh or frozen sperm samples from the previous day. Exact timing of polar body extrusion of delayed-matured MI/GV was not identified.

Wider implications of the findings

The results of this study might provide guidance to the IVF laboratories for targeting the patient population who would benefit from MII-D1 ICSI without adhering to unnecessary costs and workload.

Trial registration number

not applicable

P-628 Do ovarian reserve markers and female age predict the rate of euploid blastocysts in IVF/ICSI cycles?

Study question

Are female age and ovarian reserve markers (anti-Mullerian hormone (AMH) and Antral Follicle Count (AFC)), able to predict euploid blastocyst rate in IVF/ICSI cycles?

Summary answer

Female age, serum AMH, AFC and the number of mature oocytes collected during IVF/ICSI cycles significantly affect the rate of euploid blastocysts

What is known already

The age-associated decline in female reproduction has been clearly demonstrated, due to the reduction of the ovarian reserve and the increased risk of chromosomal abnormality occurring in the oocyte. Lately, it has been debated whether a reduced ovarian reserve, independently of age, could be associated with higher aneuploidy rate in embryos. Ovarian reserve can now be accurately measured by serum AMH levels and AFC, both markers with similar high reliability.

Study design, size, duration

This analysis includes data from 10556 blastocysts after preimplantation genetic testing for aneuploidy (PGT-A) with Next Generation Sequencing (NGS). Embryos were obtained from 2564 IVF/ICSI cycles of infertile couples, at ART Fertility Clinics UAE, from November 2016 to December 2020.

Participants/materials, setting, methods

10556 blastocysts with chromosomal information for ploidy were included, mosaic and non-informative embryos were excluded. Trophectoderm biopsy was performed on day 5, 6 or 7 blastocysts. Serum AMH concentrations were measured by Elecsys® AMH automated assay (Cobas 601 platform, Roche®) for all patients in a single laboratory. AFC (sum of small antral follicles in both ovaries) was evaluated with transvaginal 2D-sonography (Voluson E8, GE Healthcare). Ethical approval was obtained from the Research Ethics Committee (REFA023b).

Main results and the role of chance

Patients’ characteristics are described as mean ± SD (min-max): age: 34.72±6.13(18-50), years of infertility: 3.43±3.43(0-25), AMH: 2.52±2.70ng/mL(0.01-23.00), AFC: 11.57±7.86(0-61), body mass index (BMI): 28.57±4.83Kg/m2(14.34-44.96), Metaphase II (MII) inseminated oocytes: 10.11±6.53(1-50), 2PN embryos 7.32±5.12(1-42), blastocysts 4.12±3.21(1-26). Fertilization rate was 73.31%(±19.30), blastulation rate 61.05%(±25.69) and euploidy rate 39.42%(±35.24).

A significant negative Pearson correlation coefficient was found between age and euploidy rate (ρ=-0.5398, p < 0.001). AMH, AFC and total of MII inseminated oocytes showed a significant positive Pearson correlation coefficient with euploid rate (AMH:ρ=0.2076, p < 0.001; AFC: ρ = 0.2578, p < 0.001; MII:ρ=0.2036, p < 0.001). Linear regression analysis was conducted to evaluate the predictability of the variables on euploid rate. As expected, age clearly had a negative impact (Coef=-3.10, Std. Err=0.10, p < 0.0001). A positive effect was observed for AMH (Coef=2.75, Std. Err=0.31, p < 0.0001), AFC (Coef=1.16, Std. Err=0.09, p < 0.0001), number of MII inseminated oocytes (Coef=1.10, Std. Err=0.10, p < 0.0001) and 2PN embryos (Coef=1.43, Std. Err=0.13, p < 0.0001). For patients >35 years old and AMH lower than 1.3 ng/mL, euploid rate was significantly lower compared with the patients >35 years old and AMH equal or higher than 1.3 ng/mL (21.2% vs 25.5%, p = 0.0192).

Limitations, reasons for caution

Despite the large number of cycles and embryos included, the retrospective study design is a limitation.

Wider implications of the findings

Ovarian reserve is not only a quantitative, but also a qualitative biomarker of oocyte-embryo competence. Cumulative success rates for IVF/ICSI cycles are dependent on the availability of euploid blastocysts. Age and ovarian reserve markers should be combined for adequate counselling.

Trial registration number

Not applicable

O-255 Clinical and laboratory factors associated with pregnancy outcomes in patients undergoing frozen euploid blastocyst transfer

Study question

Which variables do have an impact on the pregnancy and live birth rates (LBR) when euploid frozen embryo transfers (FET) are performed?

Summary answer

Day of trophectoderm biopsy, Body Mass Index (BMI) and endometrial preparation protocol have an impact on pregnancy rate (PR) and LBR in FET cycles.

What is known already

Preimplantation genetic testing for aneuploidy (PGT-A) and morphological grading of embryos are the two main criteria to select a blastocyst from a pool of embryos, having the highest implantation potential. However, other clinical and laboratory variables might play a crucial role for a successful outcome when top quality euploid embryos are transferred in a FET cycle. It has been described that higher BMI increases the odds for miscarriage when compared with non-obese women.

Study design, size, duration

This analysis includes 1660 FET cycles with data from of pregnancy rates, miscarriage rate and LBR. Embryos were obtained from 2564 IVF/ICSI cycles of couples with primary or secondary infertility at ART Fertility Clinics UAE, from November 2016 to December 2020.

Participants/materials, setting, methods

A total of 1660 FET cycles with 2439 euploid blastocysts were included. FET cycles with mosaic or segmental aneuploid embryos were excluded. PGT-A was performed on trophectoderm cells, using Next Generation Sequencing (NGS). Biopsy was performed on day 5, 6 or 7 blastocysts. Endometrial preparation included ovulatory natural cycles (NC) and hormone replacement therapy (HRT) cycles, chosen according to physician’s discretion. Ethical approval was obtained from the Research Ethics Committee (REFA023b).

Main results and the role of chance

Patients’ characteristics are described as mean±SD (min-max): age: 33.5±5.43(19-47), AMH: 3.30±3.05ng/mL(0.01-23.00), BMI: 27.1±4.87Kg/m2(13.1-43.90), mean number of blastocysts transferred: 1.4±0.49(1-3). Patients were categorized according to age (years) in 4 categories (<30,n=404; 30-34,n=487; 35-40,n=595; >40,n=174) and no association with pregnancy rate (PR, p = 0.856), biochemical miscarriage rate (BMR, p = 0.940), clinical miscarriage rate (CMR, p = 0.06) nor LBR (p = 0.154) was found. BMI (kg/m2) was divided into four groups according to World Health Organization: underweight (<18.5;n=32), normal weight (18.5–24.9;n=555), overweight (25–29.9;n=622), and obese (≥30;n=426). Although no differences were seen for PR or BMR between groups (p = 0.507 and p = 0.343, respectively), CMR was significantly lower for normal BMI group (p < 0.001) and LBR significantly higher when compared to the overweight and obese group (<18.5kg/m2=68.42%; 18.5–24.9kg/m2=68.35%; 25–29.9kg/m2=60.14%; ≥30kg/m2=53.29%; p < 0.001). No differences were observed on the outcomes when AMH was sub-divided as per Bologna Criteria (<1.3ng/mL,n=327; ≥1.3ng/mL,n=1090). Regarding endometrial preparation, NC protocol showed significantly lower BMR and CMR (7.93% vs 12.27%,p=0.026; 8.44% vs 17.97%,p<0.001), and higher LBR (70.33% vs 55.06%,p<0.001) compared to HRT. Day of trophectoderm biopsy had a significant higher PR for day 5 (day 5=75.58% vs day 6=61.1% and day 7=23.81%, p < 0.0001), yet no differences were observed for BMR, CMR nor LBR.

Limitations, reasons for caution

Although the large number of FET included, performed in the same centre with same methodology, the retrospective study design is a limitation. We could not discard other hypothetical variables contributing to miscarriage such as KIR-HLA discrepancies, or other obstetric factors affecting late miscarriage and live birth.

Wider implications of the findings

Evaluating the factors associated with pregnancy outcomes should be considered prior to euploid frozen embryo transfer for personalized treatment approach and adequate blastocyst selection. Women with higher BMI should be aware of higher risk of miscarriage and lower LBR although an euploid blastocyst is transferred.

Trial registration number

not applicable

P-379 Ongoing pregnancy rate (OPR) of day (D) 7 euploid blastocysts is inferior to D5/D6 euploid blastocysts in frozen embryo transfer (FET) cycles

Study question

Do delayed-grown D7 euploid blastocysts have similar OPRs as D5 or D6 euploid blastocysts in FET cycles?

Summary answer

Although OPR is significantly higher with D5/D6 euploid blastocysts than D7, patients aged >38 years might benefit when slow-developing blastocysts are routinely cultured till D7.

What is known already

Current IVF practice suggests that embryos of optimal development reach blastocyst stage 116±2 hours after insemination. Recently, high reproductive potential has been reported with D6 as well as with D7 blastocysts. Although D7 blastocysts have a delayed embryo development, euploidy rates range between 25% and 49% if biopsy is performed. Usable D7 blastocysts represent nearly 5% of embryos in IVF with acceptable pregnancy and live birth rates, however, data are still limited. Therefore, further evidence of FET outcomes with D5, D6 and D7 euploid blastocysts are needed to investigate whether prolonged in-vitro embryo culture till D7 should be performed routinely.

Study design, size, duration

A single centre observational study was performed between June 2017 and November 2021, including 1396 single euploid FET cycles with blastocysts biopsied on D5 (N = 795), D6 (N = 572) or D7 (N = 29). Patients underwent endometrial preparation for a FET in a natural cycle (NC) or hormone replacement treatment (HRT). Only blastocysts graded ≥ BL3CC (Gardner scoring) before trophectoderm (TE) biopsy on D5, D6 or D7, which re-expanded within 1-hour post-warming, were considered in the analysis.

Participants/materials, setting, methods

All warmed blastocysts were transferred after 120 hours of progesterone (P4) exposure. In NC, P4 was administered after ovulation until pregnancy test (PT). For HRT cycles, estradiol was prescribed until endometrial thickness reached ≥6 mm or a trilaminar pattern was seen on which P4 was supplemented until PT. OPR was recorded at 12 weeks by the presence of a gestational sac/s and fetal heartbeat. A multivariate logistic regression model with generalized estimating equation was performed.

Main results and the role of chance

Women’s mean age differed significantly for FET cycles performed with D5, D6 and D7 euploid blastocysts (33.2±5.6, 34.5±5.3 and 36.1±4.5 years old; P < 0.001) as well as AMH values (ng/mL) (3.6±3.6, 2.9±2.8 and 2.3±1.8; P < 0.001; respectively). OPR with D5 euploid blastocysts was significantly higher than D6 and D7 (55.6%, 44.9% and 10.3%; P < 0.001), however, miscarriage rates did not differ (9.3%, 6.6% and 6.9%; P = 0.201; respectively). Following an adjusted multivariate logistic regression model, the factors associated with a reduced OPR were: D7 FETs (OR: 0.19 [0.06-0.63]; P = 0.006), ICM grade C (OR: 0.29 [0.17-0.48]; P < 0.001) and TE grade C (OR: 0.58 [0.38-0.89]; P = 0.012). Contrary, OPR outcomes were increased in NC compared to HRT cycles (OR: 1.35 [1.06-1.71]; P = 0.013). A sub-analysis showed that advanced maternal age was a risk factor of having a D7 FET cycle (OR: 1.09 [1.01-1.17]; P = 0.025). In patients >38 years, OPR was improved if D7 FET cycles were performed however, this finding was nonsignificant (OR: 2.33 [0.19-29.4], P = 0.510). In patients <38 years, D7 FET cycles were significantly negatively associated with OPR outcomes (OR: 0.07 [0.01-0.54], P = 0.011). Regardless of patient’s age, OPR outcomes with D5/D6 were higher than D7 FETs.

Limitations, reasons for caution

The current results are based on an observational study including a limited sample size of D7 euploid blastocysts FET cycles. Additionally, live birth rates should be considered in a further analysis to validate the performance of D5 and D6, compared to D7 euploid blastocysts, in both, NC and HRT cycles.

Wider implications of the findings

Considering age as a risk factor of having delayed grown blastocysts in-vitro, culturing embryos till D7 can be a strategy to increase OPR in patients >38 years old. With an increase in age, patients are more likely to have blastocysts biopsied on D6/D7. OPR outcomes are increased in NC FETs.

Trial registration number

non-clinical trials

P-537 PRIMARY SEX RATIO IS DECREASED IN EUPLOID EMBRYOS OF CONSANGUINE COUPLES AFTER IVF/ICSI WITH PGT-A

Study question

What is the primary sex ratio outcome of embryos from consanguine couples as per PGT-A analysis during IVF/ICSI treatments?

Summary answer

The primary sex ratio (PSR) (males-to-females) is decreased in euploid blastocysts from consanguine couples.

What is known already

In the general population, the sex ratio (males-to-females) tends to be 1:1 (approximately 101 males to 100 females). In epidemiological studies secondary sex-ratio (ratio at the time of birth) of inbred-offspring seems to be equilibrated. However, it is well known that there is an increased incidence of autosomal recessive diseases for the offspring, compared to non-consanguineous couples. Studies have found elevated autosomal inheritances as compared to sex-linked inheritance. Assessing the impact of consanguinity on developed embryos might contribute to the understanding of the events leading to genetic diseases.

Study design, size, duration

This analysis includes data from 5135 blastocysts after preimplantation genetic testing for aneuploidy (PGT-A) with NGS. Embryos were obtained from 1836 IVF/ICSI cycles of infertile couples, at ART Fertility Clinics UAE, from November 2016 to December 2020. Consanguinity was defined when couple were first-degree or second-degree cousins.

Participants/materials, setting, methods

A total of 1138 blastocysts from consanguine couples, and 3997 from non-consanguine couples were included in the analysis. All blastocysts presented normal sexual chromosome constitution with or without autosomal aneuploidies. Mosaic and non-informative embryos were excluded. Trophectoderm biopsy was performed on day 5 for PGT-A using Next Generation Sequencing (NGS) platform. Primary sex ratio (PSR) was observed for CG and NCG couples. Ethical approval was obtained from the Research Ethics Committee (REFA023b).

Main results and the role of chance

In consanguine couples the age of female and male partner was 30.7±5.5 and 35.9 ±5.3 years old, respectively; while non consanguine couples were older (32.2±5.8 and 37.6±7.3 years old, respectively) (p < 0.001).

Expanded blastocysts deriving from consanguine couples had 52.3% of XX versus 47.7% of XY constitution of their trophectoderm biopsied cells, presenting thus a significant decrease in primary sex ratio (PSR: 0.91, p = 0.03). In non-consanguine couples, about 51.2% of trophectoderm biopsied cells had a XX constitution compared to 48.8% of XY constitution, presenting a PSR of 0.95 (NS).

The significant decreased PSR in consanguine couples was only related to normal euploid embryos and not to abnormal embryos (PSR of abnormal embryos = 0.98; NS). Euploid embryos from couples presenting consanguinity generated 53.4% of blastocysts of XX constitution versus 46.6% of XY constitution with a PSR at 0.87 (p = 0.01).

Euploid embryos from non-consanguine couples presented a PSR at 0.96 (p=NS) (50.9% blastocysts of XX constitution versus 49.1% with XY constitution).

Limitations, reasons for caution

Differences in PSR between consanguine and non-consanguine couples did not reach significance level, justified by the lower number of embryos derived from consanguinity compared to non-consanguinity couples. Moreover 85% of the population included derives from Arabian Peninsula, therefore these results should not be transposed to other consanguine populations.

Wider implications of the findings

It is known that consanguine couples derive embryos with increased abnormalities in comparison to the general population. The fact that euploid embryos from consanguine couples seems to present a higher female constitution might incite us to investigate to what extent does heterozygosity for x-linked loci contribute to embryo survival.

Trial registration number

not applicable

P-137 ICM and TE quality significantly impact the live birth in euploid frozen blastocyst transfer cycles

Study question

Is the live birth rate (LBR) in euploid frozen blastocyst transfer (FET) affected by the quality of ICM (Inner cell mass) and TE (Trophectoderm)?

Summary answer

ICM and TE significantly impacts the LBR with a decline of LB from 57.3% (ICM-A) to 48.5% (ICM-B) to 22.1% (ICM-C) (p < 0.001)

What is known already

The morphological blastocyst grading system proposed by Gardner-Schoolcraft remains the most accepted system to identify blastocysts with higher implantation potential. It relies on morphological features within the blastocyst, including ICM and TE. Several studies tried to identify the individual contribution of each. However, the conclusions remain contradictory and no clear consensus has yet been achieved. Due to heterogeneity of parameters evaluated between different publications, where embryos with unknown ploidy status were transferred in conjunction with a variability of stimulation protocols and in the number of transferred embryos, the real effect of the ICM and TE is difficult to infer.

Study design, size, duration

This two-center retrospective observational study includes a total of 977 euploid single FET cycles between March 2017 and March 2020 at ART Fertility Clinics Muscat, Oman and Abu Dhabi, UAE.

Participants/materials, setting, methods

Trophectoderm biopsies were analyzed with Next Generation Sequencing (NGS). All blastocysts available on D5 or D6 with a quality ≥ BL3CC were subjected to TE biopsy for PGT-A analysis and LBR was recorded. Vitrification/warming of blastocysts was performed using Cryotop method (Kitazato). Bivariate and multivariate analysis were performed between LB outcomes and ICM and TE grade while controlling for confounding factors.

Main results and the role of chance

A total of 977 single FET cycles were analyzed: 651 in hormone replacement therapy (HRT) and 326 in natural cycle regimen (NC) resulting in a 46.88% LBR. The mean patients’ age was 33.80 years with a mean Body Mass Index (BMI) of 26.80 kg/m2. Though all qualities of ICM and TE were associated with LB, blastocyst ICM-A LBR was statistically significantly higher (57.3%) than ICM-B (48.4%) and ICM-C (22.1%) (p < 0.001). Similarly, blastocyst TE-A LBR was statistically significantly higher (59.2%) than TE- B (48.6%) and TE- C (30.3%) (p < 0.001). Miscarriage rate was similar in all groups.

The grade of ICM and TE were significantly associated with Anti-Mullerian-Hormone (AMH) and day of blastocyst biopsy. Mean AMH (ng/ml) was higher in ICM groups (A: 3.78, B: 3.24, p < 0.001) and TE group (A: 3.63, B: 3.38, p < 0.05) compared to lower grade (ICM-C: 2.86, TE-C: 2.82).

In multivariate analysis, endometrial preparation for FET, BMI and AMH were the parameters influencing LBR: OR:1.45, [CI:1.07-1.96], p < 0.015) for NC; OR 0.96 [CI:0.93-0.99], p = 0.004 for BMI; OR 0.95 [CI:0.90-1.00], p = 0.033 for AMH; Both, ICM-C and TE-C, resulted in a significantly lower chance of LB [ICM: OR 0.32, CI:0.17-0.61, p < 0.001; TE: OR 0.44, CI:0.27-0.73, p = 0.002), compared to grade A.

Limitations, reasons for caution

The retrospective nature of the study and inter-observer variability in blastocyst scoring is a limitation. The physician/embryologist performing the embryo transfer could not been standardized due to the multicenter design. Randomized controlled studies are needed to determine whether ICM or TE should be prioritized in the selection of the blastocyst.

Wider implications of the findings

The ICM and TE scoring in FET may influence the LBR and should be considered as an important factor for the success of embryo transfer cycles. Whether these results can be extrapolated to fresh embryo transfer and to blastocysts with unknown ploidy status, needs further investigation.

Trial registration number

not applicable

Evolution of serum progesterone levels in the very early luteal phase of stimulated IVF/ICSI cycles post hCG trigger: a proof of concept study

BACKGROUND

Studies have suggested that controlled ovarian hyperstimulation adversely affects endometrial receptivity due to advanced endometrial maturation. This adverse effect is mainly attributed to supraphysiological levels of both estrogen and progesterone identified in stimulated cycles. There is a paucity of published data investigating the very early luteal steroid profile following hCG trigger.

AIM OF THE STUDY

This prospective, observational study was undertaken to determine the increase in serum progesterone levels after human chorionic gonadotrophin (hCG) trigger in stimulated IVF/ICSI cycles.

MATERIALS AND METHODS

This proof-of-concept study included 11 patients requiring ovarian stimulation for IVF/ICSI and who planned to avail of pre-implantation genetic screening with embryo vitrification of their biopsied embryos at blastocyst stage. For each study participant, five additional blood samples were drawn at the following specific times in the stimulation cycle, on the morning (10.00-12.00) of the assigned day to induce final oocyte maturation with hCG trigger, immediately prior to administration of hCG for final oocyte maturation, 1 h, 2 h, and 36 h post hCG trigger. A prediction model, the Gompertz curve, was used to determine serum progesterone levels at intervals between the 2 h post hCG trigger sample and the day of oocyte retrieval.

RESULTS

Statistically significant increases in serum progesterone levels were identified following hCG administration as early as 1 h following trigger (P4 0.57 ng/ml, p < 0.05), 2 h following trigger (P4 0.88 ng/ml, p < 0.001) and on the day of oocyte retrieval (P4 9.68 ng/ml, p < 0.001). According to our prediction model, the Gompertz curve, the projected serum progesterone level at 4 h post trigger would have achieved a level of 1.45 ng/ml, 8 h post trigger of 3.04 ng/ml, and 12 h post trigger of 4.8 ng/ml. The very early and significant increases in serum progesterone following hCG trigger are clearly demonstrated in this study.

CONCLUSION

The endometrium is undoubtedly exposed to rapidly increasing serum progesterone levels post hCG trigger that would not be identified until much later in natural menstrual cycles.

TRIAL REGISTRATION NUMBER

This study is registered with clinicaltrials.gov under the identifier NCT04417569.

Day 5 vs day 6 single euploid blastocyst frozen embryo transfers: which variables do have an impact on the clinical pregnancy rates?

OBJECTIVE

To determine which variables affect most the clinical pregnancy rate with positive fetal heartbeat (CPR FHB+) when frozen embryo transfer (FET) cycles are performed with day 5 (D5) or day 6 (D6) euploid blastocysts. Design and method A single center retrospective study was performed from March 2017 till February 2021 including all single FET cycles with euploid D5 or D6 blastocysts and transferred in natural cycles (NC) or hormone replacement therapy (HRT) cycles. Trophectoderm (TE) and inner cell mass (ICM) qualities were recorded before biopsy.

RESULTS

A total of 1102 FET cycles were included, 678 with D5 and 424 with D6 blastocysts. Pregnancy rate (PR), clinical PR (CPR), and CPR FHB+ were significantly higher with D5 blastocysts (PR: 70.7% vs 62.0%, OR = 0.68 [0.53-0.89], p = 0.004; CPR: 63.7% vs 54.2%, OR = 0.68 [0.52-0.96], p = 0.002 and CPR FHB+: 57.8% vs 49.8%, OR = 0.72 [0.53-0.96], p = 0.011). However, miscarriage rate (12.5% vs 11.4%, OR = 0.78 [0.48-1.26], p = 0.311) did not differ. From a multivariate logistic regression model, endometrial thickness (OR = 1.11 [1.01-1.22], p = 0.028), patient's age (OR = 1.03 [1.00-1.05], p = 0.021), BMI (OR = 0.97 [0.94-0.99], p = 0.023), and ICM grade C (OR = 0.23 [0.13-0.43], p < 0.001) were significant in predicting CPR FHB+.

CONCLUSION

Although clinical outcomes are higher with D5 blastocysts, CPR FHB+ is more affected by endometrial thickness, patient age, BMI, and ICM grade C rather than biopsy day or endometrial preparation protocol.

Reintroducing serum FSH measurement during ovarian stimulation for ART

RESEARCH QUESTION

What is the impact of systemic FSH concentrations during ovarian stimulation for IVF/intracytoplasmic sperm injection on systemic progesterone concentrations in the late follicular phase?

DESIGN

Post-hoc analysis of a previously performed randomized controlled trial (RCT) performed between November 2017 and February 2020 in a tertiary IVF centre. The RCT included patients with infertility undergoing ovarian stimulation in a gonadotrophin-releasing hormone (GnRH) antagonist protocol. The GnRH antagonist was administered at 08:00 h and recombinant FSH at 20:00 h. Ultrasound and blood tests were performed 3-5 h after the GnRH antagonist.

RESULTS

The subgroup analysis comprised 105 patients. Systemic FSH concentrations increased from Day 2/3 until initiation of GnRH antagonist and remained constant until the day of trigger (DoT). The total group was split according to the median FSH DoT concentration (12.95 IU/l; Group A <12.95 IU/l; Group B ≥12.95 IU/l). Significant differences, with the higher concentrations in Group B, were found for: systemic FSH concentration on Day 2/3 (P = 0.04), total gonadotrophin dosage (P = 0.03), progesterone on DoT (P = 0.001) and progesterone per follicle (P = 0.004). In the total group, systemic DoT FSH concentration was statistically significantly positively correlated with the DoT progesterone concentration and the ratio of progesterone per follicle (ρ = 0.37 and 0.38, respectively, both P < 0.001). No significant correlations were seen between the systemic DoT FSH concentration and the number of retrieved oocytes.

CONCLUSION

While ovarian response seems to be independent from the systemic FSH concentrations on the DoT, high concentrations of circulatory FSH augment the production of progesterone.

The position of the euploid blastocyst in the uterine cavity influences implantation

RESEARCH QUESTION

Does the position of the euploid blastocyst in the uterine cavity upon transfer, measured as distance in millimetres (mm) from the fundus (DFF) to the air bubble, influence implantation potential?

DESIGN

A total of 507 single/double euploid frozen embryo transfer (FET) cycles at blastocyst stage were included retrospectively between March 2017 and November 2018 at a single centre. The patients were on average 33.3 years old. The FET were performed in natural cycles (n = 151) or hormone replacement therapy cycles (n = 356).

RESULTS

Of the 507 transfers, 370 (73.0%) resulted in a pregnancy, defined as human chorionic gonadotrophin concentration over 15 mIU/ml, and 341 (67.3%) in a clinical pregnancy, with an implantation rate of 62.0% and ongoing pregnancy rate of 59.6% (302/507). When comparing the number of embryos transferred, the pregnancy rate, clinical pregnancy rate and ongoing pregnancy rate were significantly higher after double-embryo transfer (DET) (P = 0.002: P < 0.001 and P = 0.002). The quality of the blastocyst in the single-embryo transfer group had a positive effect on the pregnancy rate (A versus B, P = 0.016; A versus C, P = 0.003) and clinical pregnancy rate (A versus C, P = 0.013). After performing a multivariate logistic regression analysis to consider the effect of all explanatory variables, a negative effect between DFF and pregnancy (P = 0.001), clinical pregnancy (P = 0.001) and ongoing pregnancy (P = 0.030) was found. When all variables remained constant, an increase of 1 mm of DFF changed the odds of pregnancy by 0.882, of clinical pregnancy by 0.891 and of ongoing pregnancy by 0.925. No significant effect of DFF was found on the miscarriage outcome (P = 0.089).

CONCLUSIONS

The depth of blastocyst replacement inside the uterine cavity may influence the pregnancy, clinical pregnancy and ongoing pregnancy rates and should be considered as an important factor to improve the success of IVF cycles.

P–584 Female parental consanguinity is associated with a reduced ovarian reserve: a large observational study including 2198 women from the Arabian Peninsula

Study question

Is parental consanguinity associated with reduced ovarian reserve in women from the Arabian Peninsula? Summary answer: Women descending from consanguineous unions have a reduced ovarian reserve compared with daughters of non-consanguine couples.

What is known already

Consanguineous marriage is defined as marriage between second-degree cousins or closer, with high prevalence in the Arabian Peninsula societies. An increased incidence of autosomal recessive diseases has been described in consanguineous marriages compared with non-consanguineous marriages. Despite the known adverse genetic impact of consanguinity, most available studies focus on the fertility of the consanguine couple. Only few publications, including low number of women, evaluated the impact of consanguinity on the fertility of their offspring, suggesting that daughters of consanguine parents might have reduced fertility associated to reduced ovarian reserve.

Study design, size, duration

A retrospective large-scale observational study was performed including 2482 women from the Arabian Peninsula who had their serum AMH and AFC measured as part of their fertility assessment at ART Fertility Clinics (UAE and Oman), from May 2015 to November 2019.

Participants/materials, setting, methods

2482 women from the Arabian Peninsula, aged 19–50 years, were assessed. Consanguinity was defined as women whose parents were first-degree or second-degree cousins. Ovarian reserve was evaluated by Antral Follicle Count (AFC) with transvaginal ultrasound and serum AMH, measured by Elecsys (Cobas, Roche®) for all participants. Women with adnexal surgery history or/and hormonal treatment within previous three months (n = 284) were excluded. Ethical approval was obtained from the Research Ethics Committee (REFA040).

Main results and the role of chance

After excluding women with previous adnexal surgeries, 2198 women were included for analysis. A total of 605 participants (27.53%) were descendants from consanguineous unions and 1593 (72.47%) reported non-consanguineous kinship of their parents. AMH and AFC (mean±SD) for the consanguineous group were 2.62±2.88 ng/mL and 12.78±9.73 antral follicles, respectively; and AMH and AFC (mean±SD) for the non-consanguineous group were 2.65±2.91 ng/mL and 13.07±9.39 antral follicles, respectively. Women from the consanguinity group were significantly younger (mean±SD: 33.74±6.64 years old) compared with the non-consanguinity group (mean±SD: 34.78±6.64 years old, p &lt; 0.0001). Both groups were similar in BMI (mean±SD: 28.63±5.46 versus 28.41±5.60 kg/m2, p=ns), years of infertility (mean±SD: 3.80±3.68 vs 4.04±3.79, p=ns), type of infertility (primary/secondary), dress code (Hijab/Niqab) and smoking status. As expected, AMH and AFC exhibit an age-dependent decline. To evaluate the differences on ovarian reserve between both groups, a multivariate analysis was performed including age, consanguinity and AMH/AFC. Women from the consanguine group showed significantly lower levels of serum AMH (R2=0.264, p = 0.036) and AFC (R2=0.286, p = 0.003) compared with non-consanguineous women, and the highest differences were found for women below 35 years of age (AMH p = 0.035; AFC p = 0.001).

Limitations, reasons for caution

Despite the large number of women included, the retrospective study design is a limitation. Results have to be treated with caution before translating into other populations, as these data are obtained from women native to the Arabian Peninsula, with high sociocultural/religious/ethnical similarities, which might differ to other consanguine populations.

Wider implications of the findings: Female parental consanguinity is associated with reduced ovarian reserve in the studied population, that might contribute to infertility. Future studies should examine the genetic and epigenetic basis of the current findings. Comprehensive clinical evaluation should include extensive family history and subsequent counselling of the affected couples.

Trial registration number

Not applicable

P–571 Preimplantation Genetic Testing for Aneuploidies (PGT-A) and pregnancy outcome

Study question

Frozen embryo transfer (FET) of euploid blastocysts in hormone replacement therapy (HRT) or natural cycle (NC): are there differences in obstetric, fetal and neonatal outcomes?

Summary answer

Pregnancy complications, neonatal outcomes and fetal abnormalities are not increased after FET with PGT-A in singleton pregnancies.

What is known already

Since its introduction, PGT has been widely used in ART centers for preventing chromosomal and monogenic diseases. Despite its increased use, there are scarce and conflicting data about adverse pregnancy, fetal and neonatal outcomes. In one published study, the risk of preeclampsia and placenta previa was increased when PGT pregnancies were compared with non-PGT, while the incidence of gestational diabetes mellitus (GDM), preterm delivery, fetal defects and NICU (Neonatal Intensive Care Unit) admission were similar. According to other data, the rate of caesarean section in PGT pregnancies was high - around 80% in singletons.

Study design, size, duration

An observational, retrospective study was conducted between March 2015 and November 2019 in patients with singleton pregnancies after ART with PGT-A/FET/HRT and NC.

A total number of 353 patients from two fertility centers (ART Fertility Clinics Dubai and Abu Dhabi, UAE), were included. They were divided into two groups according to the endometrial preparation for FET: group A: HRT (n = 225) and group B: NC (n = 128).

Participants/materials, setting, methods

Patients with primary / secondary infertility and at least one transferable euploid blastocyst after trophectoderm biopsy, achieving an ongoing singleton pregnancy after FET were included. Endometrial preparation for FET was either performed in a NC or an HRT cycle. For this study, the following pregnancy outcomes were recorded: GDM, preeclampsia and hypertension, obstetric cholestasis, placental abnormalities, mode of delivery, preterm delivery, gestational age at delivery, birth weight, fetal abnormalities and admission to NICU.

Main results and the role of chance

There were no statistically significant differences in maternal and demographic characteristics of the studied groups. The mean maternal age was 34.05(20–45) and 34.26(23–47) years for group A and B respectively. The mean BMI was 28.31kg/m² (17.93–43.76) versus 27.93 (17.32–43.18). The ratio of nulliparous versus multiparous patients was 1:1 for both groups. Majority of the patients in both groups were of Arab ethnicity. The number of patients recorded as smokers was low and comparable in the groups. The mean gestational age at the time of delivery was comparable: 37.64 gestational weeks (24–41) versus 37.76 (26–41). The Caesarean section rate was around 50% for both groups. The rate of preterm delivery was comparable in both groups (16.9% and 18.8% for group A and B respectively). There was no detectable difference in the distribution of the birth weight in both groups with a median weight of 3000 grams of which 13.6% were low birth weight. In the studied groups, 30.5% had pregnancy complications with no observed statistically significant differences when the groups were compared. There was no increased incidence of fetal abnormalities. Admission to NICU was comparable and was related to prematurity.

Limitations, reasons for caution

The limitations of the study are the retrospective design and the small number of participants.

Wider implications of the findings: In patients with FET of an euploid embryo after PGT-A, the type of FET treatment preparation (HRT or NC) has no significant effect on pregnancy complications, birth weight and fetal abnormalities. The findings of the present study could be used to improve prenatal counselling for women undergoing ART with PGT-A.

Trial registration number

Not applicable

Ali K, Arnanz A, Ruiz F, Melado L, Lawrenz B, Munck ND, Fatemi HM. P–677 Endometrial thickness, endometrial preparation protocol and number of euploid embryos transferred, significantly impact the live birth in frozen embryo transfer cycles

Study question

Is the live birth rate (LBR) in euploid frozen embryo transfer (FET) cycles affected by the endometrial thickness (EMT)?

Summary answer

A significantly higher LBR was observed in patients with an endometrial thickness of at least 7.5mm (46.24% vs. 54.63%)

What is known already

Parameters assessing the endometrium prior planning a FET include endometrial thickness, pattern and blood flow. The impact of the endometrial thickness on ART outcomes is controversial, with conflicting results published. A recent meta-analysis evaluated whether EMT could predict pregnancy outcomes and suggested that lower EMT was associated with lower incidence of clinical pregnancy rate (CPR), implantation rate (IR) and LBR. Due to heterogeneity of parameters evaluated between different publications, where embryos with unknown ploidy status were transferred, in conjunction with variability of stimulation protocols and the number of embryos transferred, the real effect of the EMT was difficult to infer.

Study design, size, duration

This was a two-center retrospective observational study including a total of 1522 euploid FET cycles between March 2017 and March 2020 at ART Fertility Clinics Muscat, Oman and Abu Dhabi, UAE.

Participants/materials, setting, methods

Trophectoderm biopsies were analyzed with Next Generation Sequencing (NGS). Vitrification/warming of blastocysts was performed using Cryotop method (Kitazato). EMT was measured by vaginal ultrasound prior initiating the progesterone administration (± 1 day) and LBR was recorded. Multivariate analysis was performed between LB outcomes and median EMT while controlling for confounding factors.

Main results and the role of chance

A total of 1522 FET cycles were analyzed: 975 single embryo transfer (SET) and 547 double embryo transfer (DET). The mean age of the patients was 33.38 years with a mean BMI of 27.1 kg/m2. FET were performed in EMT ranging from 3 to 15 mm and 50.52% resulted in a live birth. Though potentially all ranges of EMT were associated with LB, the median EMT in patients with LB was significantly higher than the median EMT of patients without LB (7.6mm vs. 7.4mm; p &lt; 0.001).

The dataset was stratified into two groups based on the median EMT (7.5mm): &lt; 7.5mm (n = 744 cycles) and ≥ 7.5mm (n = 778 cycles). A significantly higher live birth rate was observed in ≥ 7.5mm group (46.24% vs. 54.63%. p = 0.0012).

In multivariate analysis, EMT, FET endometrial preparation protocol, and number of embryos transferred were the main parameters influencing the chance to achieve LB: OR 1.10 [1.01–1.19], p &lt; 0.015 for the EMT; OR 1.84 [1.47–2.30], p &lt; 0.0001 for Natural Cycle protocol and OR 1.55 [1.25–1.93], p &lt; 0.0001 for DET. Intercept 0.18 [0.07–0.44] p &lt; 0.0002. Female age did not reach significance: OR 1.02 [1.00–1.04], p = 0.056.

Limitations, reasons for caution

Besides the retrospective nature of the study, the inter-observer variability in EMT assessment between different physicians is a limitation. The physician and embryologist performing the embryo transfer could not been standardized due to the multicenter design of the study.

Wider implications of the findings: The EMT in FET may influence the LBR and should be considered as an important factor for the success of embryo transfer cycles. Whether these results can be extrapolated to fresh embryo transfer and to blastocysts with unknown ploidy status, needs further investigation.

Trial registration number

Not applicable

P–723 Ovarian reserve parameters and ovarian stimulation outcome for IVF/ICSI are influenced by ethnicity

Study question

Are the ovarian reserve parameters and the outcome of ovarian stimulation for IVF / ICSI influenced by ethnicity?

Summary answer

Ethnicity influences ovarian reserve parameters and the outcome of ovarian stimulation for IVF / ICSI

What is known already

Infertility affects couples worldwide and due to a lack of a standardized reporting system, the real number, especially in developing countries, might be underestimated. The etiology of infertility may differ around the world and is often subjected not only to social, cultural and religious peculiarities, but also to different genetic influences. Published data suggest that ethnicity influences the ovarian reserve as well as the outcome of Assisted-Reproductive-Techniques (ART)-treatments. Key players of a successful ART outcome are the ovarian reserve and consequently the number of oocytes retrieved. Until today, the impact of ethnical differences is not sufficiently addressed in research.

Study design, size, duration

Prospective observational study, performed in 10 infertility centers worldwide (Europe (4 centers), Middle East North Africa (MENA) region (2 centers), Iran (2 centers), South America (1 center), India (1 center)) between May 2019 and September 2020, evaluating ovarian reserve and outcome parameters of ovarian stimulation treatments for IVF/ICSI. The study was approved by the Ethical Committee of each participating center.

Participants/materials, setting, methods

Couples with primary / secondary infertility and an indication for an IVF/ICSI treatment were included into this study. Besides anamnestic data regarding the history of the infertility and self-reported ethnicity (Arab, Caucasian, Hispanic, Ohters, Persian and South Asian), data obtained during the basic fertility assessment on the ovarian reserve parameters (Antral follicle count (AFC) and Anti-Muellerian-Hormone (AMH)) as well as stimulation parameters from the ovarian stimulation treatment were collected and analyzed.

Main results and the role of chance

This study comprised 1032 couples with the following distribution of the ethnicities: Arab 21.5%, Caucasian 15.9%, Hispanic 5%, Others 1.2%, Persian 33.4%, and South Asian 23%. The unadjusted means, SD and 95%CI (Confidence Interval) of AMH (ng/ml) for the groups were 3.33±0.19 [2.95–3.71]; 2.03±0.25 [1.55–2.52]; 2.43±0.74 [0.97–3.88]; 2.76±0.96 [0.88–4.64]; 3.10±0.16 [2.79–3.41]; 3.62±0.19 [3.25–3.98], for AFC 15.52±0.53 [14.49–16.55]; 12.00±0.67 [10.69–13.31]; 12.69±1.08 [10.57–14.81]; 15.11±2.60 [10.01–20.21]; 13.58±0.42 [12.75–14.41]; 13.49±0.51 [12.49–14.48] and for the number of retrieved oocytes (rCOC) 14.08±0.61 [12.88–15.27]; 9.84±0.71 [8.44–11.24]; 7.94±1.26 [5.48–10.41]; 9.92±2.62 [4.78–15.05]; 10.83±0.49 [9.87–11.79]; 17.06±0.59 [15.90–18.21], respectively. Univariate analysis of AMH, AFC and rCOC with the ethnicities revealed highly statistically significant differences for AMH and rCOC (p &lt; 0.001, respectively) and significant differences for AFC (p = 0.0014).

As age is a major confounder for the ovarian reserve, multivariate analyses were performed. After adjusting for age, AMH was significantly different between Arab-Persian, Arab-South Asian and Arab-Caucasian (p &lt; 0.001, p &lt; 0.001, p = 0.002) and AFC statistically significant between Arab and all other ethnicities. For rCOC, besides age, also the stimulation-dosage and -duration was taken into account. Highly statistically significant differences were found for the groups Arab-Persian and Arab-Caucasian and no differences towards the other ethnical groups.

Limitations, reasons for caution

Limitations of the study are an unequal number of included patients per ethnicity and that the data for the ovarian reserve parameters and the stimulation outcome were not available for all of the included patients.

Wider implications of the findings: Counselling of couples with infertility have to take, besides all other factors, also the ethnicity of the couple into account as ethnicity influences the ovarian reserve parameters as well as the number of retrieved oocytes in ovarian stimulation cycles for IVF/ICSI.

Trial registration number

ClinicalTrials.gov Identifier: NCT03927417

P–698 Antimüllerian Hormone (AMH) value as a predictive marker of cycle ploidy outcome

Study question

Do woman with diminished ovarian reserve exhibit poor blastocyst formation and ploidy outcomes, irrespective of age?

Summary answer

Patients with extreme diminished ovarian reserve (AMH≤0.65ng/ml) have a lower chance to have at least one euploid blastocyst compared to their age-related reference population (AMH=1.3–6.25ng/ml).

What is known already

AMH is an established marker of the ovarian reserve for predicting ovarian response to ovarian stimulation and it is strongly correlated with female age.

However, it has been suggested that AMH is not only a quantitative, but also a qualitative biomarker of oocyte/embryo competence. Previous studies show conflicting outcomes as to whether reduced ovarian reserve per se is associated with decreased oocyte developmental competence, leading to increased aneuploidy rates in embryos independent of the patient’s age.

Study design, size, duration

A retrospective analysis was performed between March 2017 and July 2020 at ART Fertility Clinics (Abu Dhabi) including all couples that were triggered for final oocyte maturation and planned for Preimplantation Genetic Testing for Aneuploidies (PGT-A). Patients were stratified into four age categories [≤30, 31–35, 36–40, &gt;40 years]. For each age category patients were further divided into three AMH groups: ≤0.65ng/ml, 0.65–1.3ng/ml and 1.31–6.25ng/ml (reference group).

Participants/materials, setting, methods

Trophectoderm biopsy samples were subjected to Next Generation Sequencing. AMH serum levels (ng/ml) were determined using the commercial fully automated Elecsys® (Roche) assay. Patients with a Progesterone rise of &gt; 1.5ng/ml on the day of final oocyte maturation and patients with AMH values &gt;6.25ng/ml were excluded from the analysis. Per patient that was triggered, the chance to have at least one euploid blastocyst in that cycle, was calculated.

Main results and the role of chance

A total of 1.300 couples were included with an mean maternal age of 35.6±6.2 years, AMH of 2.1 ±1.5ng/ml and body mass index of 27.5±5.0 kg/m2. The chance to have at least one blastocyst biopsied per cycle was affected in all patients with extreme low AMH (≤0.65ng/ml), irrespective of age; ≤30 years: 58.33%–100.00%–94.84% (p &lt; 0.001); 31–35 years: 50.00%–74.55%–95.32% (p &lt; 0.001); 36–40 years: 56.52%–81.93%–92.56% (p &lt; 0.001) and ≥40 years: 38.06%–73.02%–88.24% (p &lt; 0.001), for AMH ≤0.65ng/ml, 0.65–1.3ng/ml and 1.31–6.25ng/ml, respectively. In all age categories, patients with AMH values ≤0.65ng/ml had a significantly reduced probability of having a euploid blastocyst compared to the reference group (1.31–6.25ng/ml). For women ≤30 years the chances of getting a euploid blastocyst decreased from 88.89% (n = 252) to 41.67% (n = 12) (OR 0.01 [0.03–0.30], p &lt; 0.001), for 31–35 years from 88.09% (n = 235) to 43.75% (n = 32) (OR 0.10 [0.05–0.23], p &lt; 0.001), for 36–40 years from 77.67% (n = 215) to 21.74% (n = 69) (OR 0.08 [0.04–0.15], p &lt; 0.001) and among women &gt;40 years from 29.42% (n = 102) to 6.45% (n = 155) (OR 0.16 [0.08–0–36], p &lt; 0.001). Woman within AMH range of 0.65–1.3ng/ml presented the same decreased probability of having a euploid blastocyst only when 31–35 (52.73%, n = 55) or 36–40 years old (56.63%, n = 83) (OR 0.15 [0.08–0.29], p &lt; 0.001 and OR 0.37 [0.22–0.64], p &lt; 0.001, respectively).

Limitations, reasons for caution

The main limitation of this study is its retrospective design.

Wider implications of the findings: AMH is a clear biomarker of oocyte-embryo competence. Incorporation of AMH-specific counseling recommendations into clinical practice guidelines, could lead to a more informed guidance on cycle ploidy outcomes, rather than age alone.

Trial registration number

Not applicable

P–360 Blastocyst biopsy day does have an impact on clinical pregnancies in different frozen embryo transfer (FET) regimens: natural cycle (NC) versus hormone replacement therapy (HRT)

Study question

Do euploid blastocysts biopsied on day (D) 5 or D6 differ in clinical pregnancy rates when single FET are performed in NC or HRT cycles?

Summary answer

In single FET cycles, euploid D5 blastocysts have higher clinical pregnancy rates than D6 in NC, while outcomes are comparable in HRT cycles. What is known already: The synchronization between the endometrium and the embryo development is fundamental for a successful implantation. When performing FET with euploid blastocysts biopsied on D5 or D6, higher clinical pregnancy rates have been reported with D5 blastocysts, however contradictory findings were described due to the study design heterogeneity and endometrial preparation (EP) protocol variabilities. In FET cycles, no consensus has been defined of the superiority of NC over HRT cycles when euploid blastocysts are transferred. Consequently, the question remains unanswered if the clinical pregnancy rates of single euploid FET with D5 or D6 blastocysts differ when the EP protocol remains constant.

Study design, size, duration

A single center observational study was performed between June 2017 and November 2020, including 1027 single euploid FET with blastocysts biopsied on D5 or D6. All patients with primary or secondary infertility who underwent a FET in a NC or HRT EP protocol, with blastocysts graded ≥ BL3CC (Gardner scoring system) prior to biopsy were included. Vitrified-warmed blastocysts that did not re-expand within 1-hour post-warming were excluded from the analysis.

Participants/materials, setting, methods

In NCs, vaginal progesterone (P4) (Endometrin®) was administrated (3x100mg) after endocrinological confirmation of ovulation until pregnancy test. For HRT cycles, oral estradiol administration was started on day 2 (4 mg) and increased to 6mg on D5 of the cycle. When endometrial thickness was ≥6 mm, P4 was given (3x100mg) until pregnancy test. All FET were performed on D5 after start of P4 administration. Clinical pregnancy was recorded as the presence of an intrauterine gestational sac.

Main results and the role of chance

Women’s mean age was 33.8 ± 5.5 years. A total of 651 FETs were performed with D5 euploid blastocysts (37.6% in NC and 62.4% in HRT) and 376 with D6 (43.1% in NC and 56.9% in HRT). Clinical pregnancy rate in NC was higher with D5 blastocysts compared to D6 (66.9% vs 50.0%; OR = 0.494, 95% CI = 0.322–0.758; p &lt; 0.001), while no significant differences were found when vitrified-warmed blastocysts were transferred in HRT cycles (64.3% vs 58.4%; OR = 0.781, 95% CI = 0.548–1.112; p = 0.164). Additionally, clinical miscarriage was significantly higher with D5 euploid blastocysts transferred in NC (D5=10.9% vs D6=3.7%, OR = 0.239, 95% CI = 0.044–0.837; p = 0.019). In HRT, miscarriage outcomes were similar between D5 and D6 euploid blastocysts (D5=18.7% vs D6=20.8%, OR = 0.781, 95% CI = 0.548–1.112; p = 0.164), but significantly higher (p &lt; 0.001) than in NC. From a multinomial logistic regression model including age, blastocyst quality and day of biopsy as confounding factors, the clinical pregnancy rate was significantly affected by D6 blastocyst biopsy (OR = 0.571, 95% CI = 0.360–0.906, p = 0.017) and inner cell mass (ICM) grade A (OR = 3.941, 95% CI = 1.149–10.402; p = 0.006) or B (OR = 2.601, 95% CI = 1.146–5.907, p = 0.022) in NC. In HRT cycles, exclusively ICM was statistically significant (OR = 2.555, 95% CI = 1.214–5.381, p = 0.015 and OR = 2.397, 95% CI = 1.286–4.470, p &lt; 0.001 for grade A and B, respectively).

Limitations, reasons for caution

The current results are based on an observational retrospective study. Live birth and perinatal outcomes should be considered in a further analysis to evaluate the performance of the NC vs HRT protocols when D5 or D6 euploid blastocysts are transferred in FET cycles.

Wider implications of the findings: While the clinical pregnancies of D5 and D6 euploid blastocysts are comparable in HRT protocols only, the miscarriage rates seem to be significantly increased as compared to NC. Further studies are required to personalize EP protocols based on the day of blastocyst biopsy in order to improve clinical outcomes.

Trial registration number

No

P–160 Sibling oocytes cultured in a time-lapse versus benchtop incubator: limited exposure of embryos outside the incubator improves outcomes

Study question

Does the limited exposure of embryos outside the incubator, during evaluation and changeover, have an impact on the blastocyst development, blastocyst quality and euploid outcomes?

Summary answer

Exposure of embryos outside the incubator, negatively impacts the number, quality and euploidy rate of day 5 blastocysts.

What is known already

The laboratory environment with its culture conditions is one of the crucial elements of the delicate equation to a successful ART outcome. It has been shown that increased fluctuations in the culture conditions have a considerable impact on the number of blastocysts obtained and cycle outcomes. Compared to conventional benchtop incubators, Time Lapse Technology (TLT) incubators capture images of the embryo and allow morphologic and morphokinetic assessment without disturbance during incubation. Several studies have been published comparing the efficiency, safety and outcome performance between conventional and TLT incubators, however, none of them explored the euploid outcomes.

Study design, size, duration

An observational sibling oocyte study was performed at ART Fertility Clinics, Abu Dhabi between March 2018 and April 2020 and included data of 796 mature oocytes injected from 42 stimulation cycles. Sibling oocytes were randomly split between 2 different incubators: 12 oocytes were assigned to the twelve wells of the EmbryoscopeTM (ES) and the remaining oocytes were cultured in a conventional benchtop incubator, G185 K-System (KS).

Participants/materials, setting, methods

Embryos from patients with primary or secondary infertility, who underwent ovarian stimulation for ICSI and PGT-A through NGS on trophectoderm biopsies, were eligible. All patients had at least 16 fresh mature oocytes, randomly allocated to two different incubators after ICSI: 503 (63.2%) oocytes were cultured in ES and 293 (36.8%) in KS. The fertilization, cleavage, useable blastocyst and euploid rates, as well as embryo/blastocyst qualities were assessed to evaluate each incubator’s performance.

Main results and the role of chance

The fertilization and cleavage rates were similar between incubators. Total useable blastocyst rate (64.8% vs 49.6%, p &lt; 0.001) was significantly higher for embryos cultured in ES, mainly due a higher percentage of blastocysts biopsied on day 5 in ES (67.8% vs 57.0%, p = 0.037), with improved quality (p = 0.008). There was no difference in the total euploid rate between ES and KS (59.9% vs 50.4%, p = 0.314), but a significantly higher euploid rate was seen for blastocysts cultured in ES and biopsied on day 5 (63.5% vs 37.4%, p = 0.001). Day 3 embryo quality and total biopsied blastocyst quality was not different between incubators. No difference was observed in the total useable blastocyst development from good (p = 0.0832) and poor (p = 0.112) quality day 3 cleavage stage embryos. However, when stratifying according to the day of blastocyst development, poor quality embryos on day 3 showed superior blastocyst formation on day 5 when cultured in ES (64.1% vs 39.1% for day 5 and 35.9% vs 60.9% for day 6, p = 0.005). Accordingly, blastocyst formation from poor quality embryos on day 3, was shifted to day 6 for embryos cultured in KS. This difference in the day of blastocyst development was not observed for good quality cleavage stage embryos (p = 0.917).

Limitations, reasons for caution

The current observational study needs confirmation in a prospective trial and should also include the implantation potential of the euploid blastocysts, which was not followed in the current study. A good prognosis population (≥16 mature oocytes) was studied and may not reflect the outcomes in patients with lower oocyte numbers.

Wider implications of the findings: This work builds evidence to the solid introduction of the TLT incubators to the clinical routine, as the reduced exposure of embryos outside the incubator – and hence decreased stress - improves the blastocyst development.

Trial registration number

NA

P–359 Blastocyst quality, transfer difficulty and endometrial thickness affect clinical pregnancy after frozen embryo transfer (FET) of euploid blastocysts in the upper uterine cavity

Study question

Which factors affect the clinical pregnancy rate (CPR) after single euploid frozen embryo transfers (FET), when the blastocyst is transferred in the upper uterine cavity area?

Summary answer

Blastocyst quality, embryo transfer difficulty and endometrial thickness affect the CPR in FET.

What is known already

There is a limited understanding of the factors affecting success rates after FET. The most important factors influencing implantation rates are patient characteristics, type of endometrial preparation, embryo quality and transfer difficulty. It has been shown that the position of the euploid blastocyst, measured as distance from the fundus (DFF) of the uterine cavity (mm), affects the implantation potential. Although the ideal location within the uterine cavity is still being debated in very heterogeneous patient populations, most studies have found that the highest pregnancy rates are obtained when the embryo is placed in the upper area of the uterine cavity.

Study design, size, duration

This single center retrospective cohort study included a total of 603 single euploid FET cycles, in the upper half of the uterine cavity, between January 2019 and November 2020 in ART Fertility Clinic Abu Dhabi, UAE.

Participants/materials, setting, methods

Trophectoderm biopsy samples were subjected to Next Generation Sequencing to screen the ploidy state. Vitrification and warming were performed using the Cryotop method (Kitazato, Biopharma). The full length of the uterine cavity and the longitudinal distance between the fundal endometrial surface and the air bubble after transfer were measured.

Main results and the role of chance

The patients were on average 33.9 (19–46) years old. The FET was performed in a natural cycle (NC) (n = 278) or hormone replacement therapy (HRT) (n = 325). Of the 603 transfers which had been performed in the upper half of the uterus, 412 (68.3%) resulted in a pregnancy and 311 (51.5%) in a clinical pregnancy. After bivariate analysis, the clinical pregnancy rate was significantly higher for high quality blastocysts (grade 1–2 versus 3–4) (p &lt; 0.001), after easy embryo transfers (p = 0.001) and for higher endometrial thickness (p = 0.027).

After performing a multivariate logistic regression analysis to consider the effect of all explanatory variables (age, Anti Müllerian hormone, body mass index, endometrial thickness, quality of the blastocyst, difficulty of the transfer [requirement of additional instrumentation], presence of mucus or blood on the transfer catheter, day 5 or day 6 biopsy, FET endometrial preparation), the clinical pregnancy was affected by the endometrial thickness: OR 1.20 [1.05–1.37], p = 0.007; transfer difficulty: OR 0.44 [0.25–0.79], p = 0.006; blastocyst quality 3: OR 0.38 [0.18–0.79], p = 0.01 and blastocyst quality 4: OR 0.15 [0.06–0.37], p &lt; 0.0001. Age did not affect the clinical pregnancy after transferring a single euploid blastocyst: OR 1.03 [1.00–1.06], p = 0.052.

Limitations, reasons for caution

The limitation of this study was its retrospective nature and the small sample size. Other parameters may be important in live birth outcomes.

Wider implications of the findings: Optimization of clinical pregnancy outcomes after FET depends on multiple factors. Even after transfer of euploid blastocysts in the upper uterine cavity, the endometrial thickness, transfer difficulty and blastocyst quality will still affect the clinical pregnancy outcomes.

Trial registration number

NA

P–271 Should intracytoplasmic sperm injection (ICSI) of delayed mature oocytes become a routine practice in the IVF Laboratory?

Study question

Do delayed mature oocytes result in similar euploid blastocyst rates as their immediate mature sibling oocytes?

Summary answer

Once a blastocyst is obtained, delayed mature oocytes have similar euploid rates compared to immediate mature oocytes.

What is known already

Intracytoplasmic sperm injection (ICSI) of metaphase II oocytes few hours post oocyte retrieval is standard practice in IVF laboratories. Immature metaphase I (MI) and prophase I (GV) oocytes are usually discarded. Immature oocytes may mature overnight, after which ICSI can be performed. Studies demonstrated lower fertilization and blastulation rates for these delayed mature oocytes. However, live births have been reported from blastocysts transferred. The evidence available is not compelling, since most of the studies had either low sample size, no preimplantation genetic testing for aneuploidies (PGT-A), or the outcome was not compared to sibling MII oocytes at time of denudation.

Study design, size, duration

A single-center retrospective sibling oocyte study was performed between January 2019 and December 2020 at ART Fertility clinics Abu Dhabi, UAE. A total of 345 PGT-A cycles, with at least one delayed mature oocyte inseminated by ICSI, were included: 2506 immediate mature oocytes and 669 delayed mature oocytes.

Participants/materials, setting, methods

Following controlled ovarian stimulation, MII oocytes at the time of denudation were inseminated by ICSI/IVF (immediate mature). Immature oocytes (MI/GV) were cultured for 16–24 hours in fertilization medium and injected the next day if matured (delayed mature). Trophectoderm biopsy was performed on day 5/6/7 and samples were subjected to Next Generation Sequencing to screen the ploidy state of the blastocyst.

Main results and the role of chance

The 345 controlled ovarian stimulation cycles resulted in the insemination of 2506 MII oocytes on the day of oocyte retrieval (Day0) and 669 delayed mature oocytes on day 1. Normal fertilization rate was significantly higher in the immediate mature oocytes compared to delayed mature oocytes (68% vs 56%, p &lt; 0.0001). Similarly, the usable blastocyst rate was significantly higher in immediate mature oocytes (59% vs 19%, p &lt; 0.0001). On day 5 of development, a significantly higher-good quality blastocyst formation rate was obtained from immediate mature oocytes (65% vs 27%, p &lt; 0.0001). The rate of good quality blastocyst on the day of biopsy was significantly higher in the immediate mature oocytes group (76% vs 62%, p &lt; 0.015).

Fisher’s Exact Test was performed to compare the euploid rate of blastocysts biopsied on day 5/6/7 originating from immediate mature oocytes or sibling delayed mature oocytes. The euploid potential of blastocyst biopsied showed no significant difference between the two groups (p = 0.388).

Limitations, reasons for caution

The timing of MI/GV oocytes transition to MII stage was not recorded since the incubation was done in a benchtop incubator. Furthermore, the same sperm sample was used to inseminate immediate and delayed mature oocytes, which might contribute to the compromised embryo development due to increased sperm DNA fragmentation.

Wider implications of the findings: Insemination of delayed mature oocytes by ICSI, should be considered as a tool to increase patients’ chances of obtaining a euploid embryo. Especially in cases where low yield of euploid embryos is expected.

Trial registration number

Not applicable