Dominant Follicle Research Articles

Landscape transcriptomic analysis of bovine follicular cells during key phases of ovarian follicular development

BackgroundThere are many gaps in our understanding of the mechanisms involved in ovarian follicular development in cattle, particularly regarding follicular deviation, acquisition of ovulatory capacity, and preovulatory changes. Molecular evaluations of ovarian follicular cells during follicular development in cattle, especially serial transcriptomic analyses across key growth phases, have not been reported. This study aims to address this gap by analyzing gene expression using RNA-seq in granulosa and antral cells recovered from ovarian follicular fluid during critical phases of ovarian follicular development in Holstein cows.ResultsIntegrated analysis of gene ontology (GO), gene set enrichment (GSEA), protein–protein interaction (PPI), and gene topology identified that differentially expressed genes (DEGs) in the largest ovarian follicles at deviation (Dev) were primarily involved in FSH-negative feedback, steroidogenesis, cell proliferation, apoptosis, and the prevention of early follicle rupture. In contrast, DEGs in the second largest follicles (DevF2) were mainly related to loss of cell viability, apoptosis, and immune cell invasion. In the dominant (PostDev) and preovulatory (PreOv) follicles, DEGs were associated with vascular changes and inflammatory responses.ConclusionsThe transcriptome of ovarian follicular fluid cells had a predominance of granulosa cells in the dominant follicle at deviation, with upregulation of genes involved in cell viability, steroidogenesis, and apoptosis prevention, whereas in the non-selected follicle there was upregulation of cell death-related transcripts. Immune cell transcripts increased significantly after deviation, particularly in preovulatory follicles, indicating strong intrafollicular chemotactic activity. We inferred that immune cell invasion occurred despite an intact basal lamina, contributing to follicular maturation.Graphical

Exploration of transcriptional regulation network between buffalo oocytes and granulosa cells and its impact on different diameter follicles

BackgroundBuffalo is a globally important livestock species, but its reproductive performance is relatively low than cattles. At present, dominant follicle development specific process and mechanistic role of follicular growth related genes in water buffaloes are not well understood. Therefore, we comprehensively performed transcriptomics of granulosa cells and oocytes from different-sized follicles in water buffalo to identify key candidate genes that influence follicle development and diameter, and further explored the potential regulatory mechanisms of granulosa cells and oocytes in the process of water buffalo follicle development.ResultsIn this study, we found918 granulosa cell transcripts and 1401 oocyte transcripts were correlated in follicles of different diameters, and the expression differences were significant. Subsequent enrichment analysis of the co-expressed differentially expressed transcripts identified several genes targeted by long non-coding RNAs (lncRNAs) and associated with follicular development. Notably, the upregulation of BUB1 regulated by MSTRG.41325.4 and interactive action of SMAD2 and SMAD7 might have key regulatory role in follicular development. Additionally, we also detected key differentially expressed genes that potentially influence follicular hormone metabolism and growth, like ID2, CHRD, TGIF2 and MAD2L1, and constructed an interaction network between lncRNA transcripts and mRNAs.ConclusionsIn summary, this study preliminarily revealed the differences in gene expression patterns among buffalo follicles of different sizes and their potential molecular regulatory mechanisms. It provides a new perspective for exploring the mechanism of buffalo follicular dominance and improving buffalo reproductive performance.

Improved reproductive outcomes in normogonadotropic oligomenorrheic women undergoing ovarian stimulation with intrauterine insemination: a retrospective cohort analysis of real-world data.

This study aimed to evaluate the comparative reproductive outcomes of ovarian stimulation combined with intrauterine insemination using partner's sperm (OS-IUI) in eumenorrheic and normogonadotropic oligomenorrheic women. A retrospective cohort study was conducted, including 3833 couples who underwent 5920 cycles of OS-IUI between June 2013 and March 2019. Participants were stratified into two cohorts based on menstrual regularity: eumenorrheic and normogonadotropic oligomenorrheic. The primary outcome measured was the live birth rate (LBR) per cycle and cumulative LBR per couple. Secondary outcomes encompassed the clinical pregnancy rate (CPR) per cycle, miscarriage rate, and multiple pregnancy rate. Propensity score matching (PSM) was utilized to balance maternal baseline characteristics. Prior to PSM, significant differences in CPR, LBR and cumulative LBR were observed between eumenorrheic and oligomenorrheic women, favoring the latter (CPR: 11.16% vs. 18.75%; LBR: 9.02% vs. 14.96%; cumulative LBR: 13.60% vs. 24.25%, P < 0.001). These differences persisted post-PSM (CPR: 9.74% vs. 19.29%; LBR: 7.30% vs. 16.29%; cumulative LBR 7.76% vs. 19.90%, P<0.001). Multivariate regression analyses revealed that menstrual status was a significant independent predictor of both CPR (adjusted odds ratio [OR]=1.83 before PSM, 2.24 after PSM) and LBR (adjusted OR=1.90 before PSM, 2.46 after PSM). In the subgroup analysis, female age was identified as the sole predictor of reproductive outcomes in oligomenorrheic women undergoing OS-IUI. Conversely, in eumenorrheic women, factors such as age, duration of infertility, body mass index (BMI), ovarian stimulation agents, and the number of dominant follicles were significant influencers of CPR and LBR. Normogonadotropic oligomenorrheic women demonstrated improved reproductive outcomes with OS-IUI, suggesting that tailored treatment strategies based on menstrual regularity could optimize success rates in infertility management.

Short-Term Metformin Therapy in Clomiphene Citrate Resistant PCOS Patients Improves Fertility Outcome by Regulating Follicular Fluid Redox Balance: A Case-Controlled Study.

To determine the effect of short-term metformin administration on follicular fluid (FF) total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI) and nuclear factor kappa B (NF-kB) in women with clomiphene citrate-resistant polycystic ovary syndrome (PCOS). Fifty-eight patients aged 23-34 who were planned to have intracytoplasmic sperm injection due to clomiphene citrate-resistant PCOS were included in the study. Participants were divided into two groups according to whether they used metformin or not. While 30 of 58 PCOS patients were using short-term metformin in combination with controlled ovarian stimulation, 28 PCOS patients were not using metformin. Metformin was started in the mid-luteal period and continued until the day before oocyte retrieval at 850 mg twice daily. To determine FF-NF-kB, TAS, TOS and OSI values, a dominant follicle ≥17-18 mm in diameter was selected for aspiration. The number of mature follicles and fertilization rates of the metformin group were significantly higher than those not taking metformin. FF-TOS and OSI of the metformin group were significantly lower than those of the group not receiving metformin. Patients receiving metformin had higher FF-TAS than the group not receiving metformin. FF-NF-kB levels of the metformin group were significantly lower than the group not receiving metformin. Insulin resistance, FF-NF-kB and FF-TOS were negatively correlated with the number of mature oocytes. FF-TAS was positively correlated with the number of oocytes. Short-term metformin treatment in clomiphene-resistant PCOS improves the number of mature follicles and fertilization rates by regulating the intra-follicle redox balance.

Gonadotropins combined with and without 100mg Clomiphene Citrate drug on ovulation induction and role of epidural analgesia in pregnancy outcome of infertility women.

Successful ovulation induction can overcome the common condition of infertility associated with ovulatory dysfunction. Monotherapy of clomiphene citrate (CC) or combined with gonadotrophins are the best treatment modalities for ovulation induction with a successful outcome. We concentrated on evaluating the effects of 100 mg Clomiphene Citrate, both with and without gonadotrophins, on ovulation induction and the outcome of labor analgesia in women with infertility. This prospective cohort consists of 136 women with infertility who were medicated with 100 mg of clomiphene citrate alone and 100 mg of clomiphene citrate with gonadotropins. We recorded the endometrial thickness, details of the dominant follicle, and the incidence of a positive pregnancy rate. Women with positive pregnancy were managed with epidural labor with labor analgesia to relieve labor pain and evaluated the foetal outcome. In CC alone, the ovulation rate was 57%, while in CC with gonadotrophins, it was 81%. The mean dominant follicle size and endometrial thickness were high in CC with gonadotrophins (p &lt; 0.05). The overall incidence of positive pregnancies was 28.98%. Levobupivacaine with dexmedetomidine significantly reduced the mean VAS score from baseline, resulting in a higher foetal body weight. Taking 100 mg of Clomiphene citrate with gonadotropins works better than taking Clomiphene citrate by itself at starting ovulation, increasing the size of the dominant follicle, and improving the thickness of the endometrium. With levobupivacaine plus dexmedetomidine, the labor analgesia showed better stability in hemodynamic parameters and effective control on labor pain scores.

Effect of intrafollicular administration of PGE2 or PGF2α in early estrus on ovulation, hemorrhagic anovulatory follicles formation, progesterone secretion and pregnancy outcome in the mare

This experiment was performed to evaluate whether intrafollicular treatment of PGE2 or PGF2α administered in early estrus would induce normal ovulation, progesterone production (Experiment 1) and pregnancy (Experiment 2). In Experiment 1, mares in estrus after 2 days of endometrial edema were injected in all largest dominant follicles (28–35 mm in diameter) with 0.5 mL of sterile water containing 500 μg PGE2 (n = 6), 125 μg PGF2α (n = 6) or placebo (n = 7) (Hour 0). Ultrasound examinations were performed daily, until ovulation or anovulation was detected, and daily blood samples were taken for 8 days. In Experiment 2, mares with a dominant follicle ≥35 mm after at least three days of slight-to-moderate endometrial edema, were injected with 500 μg PGE2 diluted in 0.5 mL of sterile water for injection in the follicle (PGE2 group; n = 9 mares and 11 dominant follicles). No puncture was performed in the control group (n = 9 mares and 11 dominant follicles). Mares from both groups were inseminated. In Experiment 1, all mares (6/6) in the PGE2 group ovulated within 24 h of treatment. The mean interval from intrafollicular injection to ovulation was shorter (P < 0.001) in PGE2 mares (24 ± 0 h) than in control mares (77 ± 9 h). Mares from the PGF2α group developed hemorrhagic anovulatory follicles (HAF) more often (7/7) than control mares (2/7); P < 0.05). The progesterone concentration in mares from the PGF2α group was lower (P < 0.004) than control mares in the early post-ovulatory period. The first significant increase in post-ovulatory progesterone concentration occurred earlier (P < 0.05) in mares from the control group than in mares from the PGF2α and PGE2 groups. In Experiment 2, more mares from the control group (7/9, 78 %) became pregnant than from the PGE2 group (2/9, 22 %) (P = 0.015). In conclusion, PGE2 alone induced follicle collapse in all treated mares within 24 h of administrations, while PGF2α blocked ovulation and induced formation of HAFs. However, the post-ovulatory rise in progesterone production was delayed and the fertility reduced in mares with ovulation induced by PGE2 compared to control mares.

Ovulation Induction Response in Non-Obese Versus Obese Women with Polycystic Ovarian Syndrome at Fertility Clinic of a Tertiary Care Hospital, Rawalpindi

Background: More than 80% of premenopausal females presenting with Polycystic Ovarian Syndrome (PCOS) have above average BMI. Obesity enhances the magnitude of hormonal and metabolic disturbances leading to anovulation. Objective: To validate the influence of obesity on response of ovulation induction by Clomiphene citrate in PCOS related subfertility. Methodology; Study Design &amp; Setting: Comparative Analytical study at Fertility Clinic of Department of Obstet &amp; Gynae, Benazir Bhutto Hospital, Rawalpindi. Study Duration: Twelve months (Dec 2020-Dec 2021) Method: Rotterdam criteria was used to diagnose PCOS. WHO criteria of BMI=23 kg/m² cutoffs for Asian population was used to divide women in two groups; non-obese (Group-A &lt; 23 kg/m²) and obese/overweight (Group-B ≥ 23 kg/m²). In both groups ovulation was induced with Clomiphene Citrate and response was assessed via ultrasound follicular tracking, Day 21 serum progesterone and serum B-HCG levels two weeks after the HCG injection. Results: Total participants were 200 (100 in each group). Mean age (years) in Group-A vs Group-B was 25.38 vs, 27.62 and mean BMI (kg/m²) was 20.82 vs 28.34 respectively. The frequent symptoms in Group-A Vs Group-B were Oligomenorrhoea (87% vs 97%) and amenorrhoea (13% vs 03%). P-value (0.009) was significant. Difference in Ultrasound features of PCOS and LH:FSH ratio in both groups were insignificant (P-value=0.214 and 0.316 respectively). The difference in almost all parameters of OI between the two groups was statistically significant. In Group-A vs Group-B; the presence of dominant follicle after Clomiphene citrate was 52% vs 34% (p value=0.01); Day 21 serum progesterone &gt;30ng/ml was 21% vs 09% (p value=0.01); a positive serum β-HCG level &gt;50 mIU/L 02 weeks after HCG administration was 12% vs 04% (p value=0.09). Conclusion: Obesity control and lifestyle modification are imperative for significant improvement in fertility outcomes for PCOS related subfertility.

Increasing dominant follicular proportion was associated with adverse IVF/ICSI outcomes in low-prognosis women undergoing GnRH antagonist protocol: a retrospective cohort study

PurposeThis study aimed to examine the correlation between different dominant follicle proportions (DFPs) and outcomes of in-vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) among patients classified under POSEIDON Groups 3 and 4, who underwent gonadotropin-releasing hormone antagonist (GnRH-ant) protocols. Additionally, it sought to determine the optimal DFP threshold for trigger timing.MethodsA retrospective analysis was performed on patients classified under POSEIDON Groups 3 (n = 593) and 4 (n = 563) who underwent GnRH-ant protocols for controlled ovarian hyperstimulation (COH) between 2016 and 2022. These patients were categorized into two groups based on their DFPs, defined as the ratio of ≥ 18-mm dominant follicles to ≥ 12-mm follicles on the trigger day (DFP ≤ 40% and DFP ≥ 40%). Statistical analyses, including restricted cubic spline (RCS) and multivariate logistic regression, were employed to assess the relationship between DFP and IVF/ICSI outcomes.ResultsDemographic characteristics of patients were similar across groups. In POSEIDON Groups 3 and 4, DFP > 40 was associated with a significant decrease in the number (No.) of oocytes retrieved, cleaved embryos, and available embryos. Moreover, following the GnRH-ant cycle, the clinical pregnancy and live birth rates in fresh embryo transfer (ET) were notably reduced in the DFP > 40 group compared with the DFP ≤ 40 group, whereas no significant differences were observed in the pregnancy outcomes of the first frozen-thawed embryo transfer (FET) between the groups. In POSEIDON Group 3, the cumulative clinical pregnancy rate (CCPR) and cumulative live birth rate (CLRB) were significantly higher in the DFP ≤ 40 subgroup than in the DFP > 40 subgroup, with a notable decrease in CLRB observed with increasing DFP levels. However, in POSEIDON Group 4, no significant differences in CCPR and CLRB were found between the groups. Logistic regression analysis identified age and the No. of oocytes retrieved as pivotal factors influencing CLRB in Group 4.ConclusionFor patients in POSEIDON Group 3, maintaining a DFP ≤ 40 mm is crucial to achieve optimal laboratory and pregnancy outcomes by avoiding delayed triggering. However, for patients in POSEIDON Group 4, age remains a critical factor influencing CLRB regardless of DFP, although a higher No. of oocytes retrieved and available embryos with DFP ≤ 40 is beneficial.

Comparison of Day-Specific Serum LH, Estradiol, and Progesterone with MiraTM Monitor Urinary LH, Estrone-3-glucuronide, and Pregnanediol-3-glucuronide Levels in Ovulatory Cycles.

Background and Objectives: Fertility tracking apps and devices are now currently available, but urinary hormone levels lack accuracy and sensitivity in timing the start of the 6-day fertile window and the precise 24 h interval of transition from ovulation to the luteal phase. We hypothesized the serum hormones estradiol (E2) and progesterone (P) might be better biomarkers for these major ovulatory cycle events, using appropriate mathematical tools. Materials and Methods: Four women provided daily blood samples for serum E2, P, and LH (luteinizing hormone) levels throughout their entire ovulatory cycles, which were indexed to the first day of dominant follicle (DF) collapse (defined as Day 0) determined by transvaginal sonography; therefore, ovulation occurred in the 24 h interval of Day -1 (last day of maximum diameter DF) to Day 0. For comparison, a MiraTM fertility monitor was used to measure daily morning urinary LH (ULH), estrone-3-glucuronide (E3G), and pregnanediol-3-glucuronide (PDG) levels in three of these cycles. Results: There were more fluctuations in the MiraTM hormone levels compared to the serum levels. Previously described methods, the Fertility Indicator Equation (FIE) and Area Under the Curve (AUC) algorithm, were tested for identifying the start of the fertile window and the ovulation/luteal transition point using the day-specific hormone levels. The FIE with E2 levels predicted the start of the 6-day fertile window on Day -7 (two cycles) and Day -5 (two cycles), whereas no identifying signal was found with E3G. However, both pairs of (E2, P) and (E3G, PDG) levels with the AUC algorithm signaled the Day -1 to Day 0 ovulation/luteal transition interval in all cycles. Conclusions: serum E2 and (E2, P) were better biomarkers for signaling the start of the 6-day fertile window, but both MiraTM and serum hormone levels were successful in timing the [Day -1, Day 0] ovulatory/luteal transition interval. These results can presently be applied to urinary hormone monitors for fertility tracking and have implications for the direction of future fertility tracking technology.

Double dosing ulipristal acetate emergency contraception for individuals with obesity: a randomised crossover trial

ObjectiveTo determine whether increasing the dose of ulipristal acetate (UPA)-containing emergency contraception (EC) improves pharmacodynamic outcomes in individuals with obesity.Study designWe enrolled healthy, regularly-cycling, confirmed ovulatory, reproductive-age individuals with body...

An Approach to Improve Endometrial Receptivity: Is It Beneficial to Flush The Uterine Cavity with Follicular Fluid and Granulosa Cells? A Phase III Randomised Clinical Trial.

The follicular fluid (FF) of mature oocytes contains a high concentration of growth factors and cytokines that have the potential to influence implantation in either a paracrine or autocrine manner. During the physiological processes of ovulation, FF enters the fallopian tubes in conjunction with the oocyte. The purpose of this study is to evaluate implantation and clinical pregnancy rates following uterine flushing with FF and granulosa cells in infertile women with moderate male factor infertility after ovum retrieval for intracytoplasmic sperm injection (ICSI). This phase III randomised clinical trial enrolled 140 women with moderate male factor infertility who intended to undergo ICSI at Royan Infertility Clinic (Tehran, Iran). A computer-generated program and opaque sealed envelopes were used to randomly allocate patients to either an intervention group (n=70) or a control group (n=70). Participants in the intervention group received 2 ml of clear FF (without blood contamination) from 2 to 3 dominant follicles after oocyte retrieval. The control group only underwent uterine cavity catheterisation. The intervention group had a clinical pregnancy rate of 38.5% (25/65) compared to the control group [42.9% (27/63); P=0.719] and an implantation rate of 24.1% compared to the control group (27%; P=0.408). These rates did not differ between the groups. There were no statistically significant differences between the intervention and control groups in terms of pregnancy-related complications-ectopic pregnancy, blighted ovum or anembryonic pregnancy, and abortion. Uterine cavity flushing with FF from mature follicles following oocyte retrieval had no effect, either positively or negatively, on clinical pregnancy or implantation rates in women with moderate male factor infertility (registration number: NCT04077970).

P-388 The science of frozen embryo transfer, is modified natural cycle better?

Abstract Study question Do live birth rate, obstetric outcomes and number of clinic visits differ between frozen embryo transfer in modified natural and artificial cycle? Summary answer Modified natural cycle yielded a higher live birth rate for the similar number of visits, less hypertension, but higher rate of gestational diabetes. What is known already A frozen embryo transfer in a modified natural cycle entails procedure timing such that it coincides with the woman’s ovulatory cycle. Conversely, a frozen embryo transfer in an artificial cycle involves controlled hormonal stimulation, with the subsequent scheduling of embryo transfer. Based on the current evidence, there is no difference in pregnancy rates between modified natural cycle and artificial cycle. Frozen embryo transfer during an artificial cycle allows for greater flexibility for the patient and physicians. However, it seems to be associated with higher risk of adverse obstetric and neonatal outcomes. Study design, size, duration 1206 frozen embryo transfer cycles between January 1st, 2022, and December 31st, 2022 were retrospectively studied. Patients older than 40, with recurrent implantation failure, and recurrent pregnancy loss were excluded. Patients were divided according to their age, BMI, AMH, and the type of embryo transfer protocol. Compared outcomes were endometrial thickness, biochemical pregnancy rate, clinical pregnancy rate, miscarriage rate, number of clinic visits prior to transfer, obstetric complications, livebirth rate, and livebirth weight. Participants/materials, setting, methods Patients in the modified natural cycle group were followed by ultrasound and when the endometrium reached a thickness ≥ 7mm, and a dominant follicle ≥ 15 mm, HCG trigger was given, and the embryo (blastocyst) transferred 7 days later. In the artificial cycle group, patients received estrogen supplementation either orally or by patches and when the endometrium reached a thickness ≥ 7 mm, embryo transfer was scheduled following intramuscular progesterone administration for 6 days. Main results and the role of chance Patients with modified natural cycle (n = 250) embryo transfers have better clinical pregnancy rate compared to the embryo transfers (n = 250) in artificial cycles (63,6% vs 55,2% p = 0,05), and significantly better live birth rate (57,2% vs 43,9% p = 0,003) despite similar biochemical pregnancy rate (64% vs 61% p = 0,48). The miscarriage rate was significantly lower in modified natural compared to artificial cycles (10,2 % vs 20,99%, p = 0,008). Similar results were found with the transfer of PGTA tested embryos. There was no difference in the endometrial thickness between the 2 groups. The number of visits was higher in the modified natural cycle group, but the difference was not clinically significant (1,57 days vs 1,2 days). When comparing the obstetric outcomes, patients with a modified natural cycle transfer had a lower risk of hypertension (6,6% vs 13,5 % p = 0,10), but a significantly higher risk of gestational diabetes (19% vs 8,3% p = 0,02). No difference was observed regarding the birth weight, percentage of preterm birth or mode of delivery. Regression analysis was performed to identify any cofounder that might have affected the clinical pregnancy rate, and the results showed that the type of transfer was the only factor affecting the outcomes (OR: 1,23 CI: 1,03- 1,46) Limitations, reasons for caution The main limitation of this study is its retrospective nature. A randomized controlled study should be performed to confirm these findings. Wider implications of the findings Modified natural embryo transfer could be used to improve pregnancy outcomes. With proper scheduling, embryo transfer could be done with a similar number of visits for modified natural cycles and artificial cycles. More studies are needed to assess the increased risk of gestational diabetes with natural cycle embryo transfer. Trial registration number NCT06053827

P-664 Insulin-like peptide 3 as a potential biomarker in predicting IVF success and ovarian reserve in women with unexplained infertility and diminishing ovarian reserve

Abstract Study question Could insulin-like peptide 3 (INSL3) predict ovarian reserve and in vitro fertilization (IVF) success in women with unexplained infertility (UI) and diminishing ovarian reserve (DOR)? Summary answer In women with DOR, reduced intrafollicular and serum INSL3 levels correspond with low AMH and high FSH levels, similar to established ovarian reserve markers. What is known already INSL3, belonging to the insulin-like peptide family, is produced by theca interna cells within antral follicles and the corpora lutea. It is hypothesized that INSL3 is integral to the initial development and function of antral follicles, specifically through its regulatory effect on androgen biosynthesis in the thecal cells of these follicles. Moreover, INSL3 is implicated in the modulation of the ovarian microenvironment, which is essential for facilitating the maturation of oocytes. Study design, size, duration This research was carried out at the IVF centers of two tertiary university hospitals, assessing 49 infertile women with either UI (n = 24) or DOR (n = 25) during IVF treatment. A control group (n = 26) comprised women with normal ovarian reserve undergoing IVF due to male or tubal factors. Outcome parameters are ovarian reserve markers (serum FSH, estradiol, AMH, INSL3 concentration and antral follicle count [AFC]), positive pregnancy rate and live birth rate (LBR) (gestational age ≥28 weeks). Participants/materials, setting, methods Women aged between 20-40 with a body mass index (BMI)&amp;lt;30 kg/m² were included. Serum FSH, estradiol, AMH, INSL3 levels and AFC were evaluated on menstrual cycle days 2 or 3, and INSL3 in follicular fluid from dominant follicles (&amp;gt;14 mm) were evaluated during oocyte retrieval. Exclusions included endocrine abnormalities (e.g., polycystic ovary syndrome, hyperprolactinemia, hypo and hyperthyroidism) cycle cancellation due to lack of a viable embryo, uncorrected Mullerian anomalies, recurrent miscarriage history and hydrosalpinx presence. Main results and the role of chance The mean age in the study groups was 28.41±3.5 (UI), 32.40±4.21 (DOR), and 29.65±3.91 (control). In the DOR group, female age (p = 0.001), BMI (p = 0.049), duration of infertility (p = 0.006), previous IVF attempts (p &amp;lt; 0.001), basal FSH (p &amp;lt; 0.001), and basal estradiol (p &amp;lt; 0.001) were higher, while AMH (p &amp;lt; 0.001), AFC (p &amp;lt; 0.001), and follicular fluid INSL3 (p &amp;lt; 0.001) were lower. Serum INSL3 in DOR was lower but not statistically significant. No correlation was found between serum INLS, follicular fluid INSL3, ovarian reserve markers, positive pregnancy rates, miscarriage, and LBR. DOR group had longer stimulation durations (p = 0.017), but lower max estradiol (p &amp;lt; 0.001), fewer oocytes (p &amp;lt; 0.001), mature follicles (p &amp;lt; 0.001), and PN (p &amp;lt; 0.001). Pregnancy rates were 54.1% (UI), 24% (DOR), and 53.84% (control); LBRs were 54.1% (UI), 20% (DOR), and 42.3% (control), with significant differences in pregnancy tests (p = 0.04) and LBR (p = 0.03), both lower in DOR. Univariate analysis identified duration of infertility (p = 0.019) and basal FSH (p = 0.009) as significant LBR predictors. Multivariable analysis confirmed basal FSH (p = 0.033) as significant, with increased duration of infertility and basal FSH level reducing LBR probability. Limitations, reasons for caution The limited sample size of our study potentially undermines the robustness of circulating INSL3 as a predictive biomarker for DOR, evidenced by the non-significant decrease in serum INSL3 levels in the DOR group. Moreover, the lack of INSL3 level assessment during oocyte retrieval further constrains our findings. Wider implications of the findings Our research explored INSL3 as a viable biomarker for predicting ovarian reserve and IVF success in UI and DOR cases. Reduced INSL3 levels in circulation and follicular fluid in DOR patients could be beneficial in clinical practice. Trial registration number not applicable

P-585 Vaginal progesterone associated with oral dydrogesterone versus vaginal progesterone for luteal support in letrozole-hcg cycles for thawed embryo transfer: a non-inferiority prospective cohort study

Abstract Study question Does micronized vaginal progesterone (MVP) associated with oral dydrogesterone (DYG) an alternative for luteal support in Letrozole-hcg cycles for thawed embryo transfer? Summary answer The association of MVP and DYG is a non-inferior alternative to only MVP for luteal support in thawed embryo transfer in Letrozole-hcg cycles. What is known already Endometrial preparation is essential for thawed embryo transfer. Several protocols involving different luteal support with progesterones are available. Moreover, the presence of corpus luteum decreases the obstetrical morbidity mainly linked to hypertensive disorders. Letrozole-hcg administration is a good alternative for frozen embryo transfer (FET). However, the literature lacks information about the comparison among the different protocols for luteal support in Letrozole-hcg cycles. Dydrogesterone is an oral progesterone with some unique characteristics which could be utilized with some advantage for luteal support, including oral administration and some immunological activity. Study design, size, duration This is a prospective non-inferiority cohort study performed at an infertility clinic including patients performing the first FET cycle during 2023. Reproductive outcomes were compared between patients receiving 600 mg (3x200 mg) of MPV or 40 mg of DYG plus 400 mg of MVP after Letrozole-hcg administration. Participants/materials, setting, methods All patients (aged 23-39 years) undergoing their first FET cycle during 2023 were included in this study (n = 169), divided into two groups: MVP+DYG (n = 54) or MVP (n = 115) for luteal support after Letrozole-hcg. Letrozole was administered for 5 days (2,5 mg/bid) and hcg was done when a dominant follicle reached 18 mm with a follicular endometrium measuring at least 7 mm. Main results and the role of chance Both groups were equivalent in terms of age, infertility aetiology, BMI and AMH (P &amp;gt; 0.05). Moreover, the proportion of cleavage or blastocyst stage was also similar between both groups (57% blastocyst transfer for MVP+DYG and 50% blastocyst transfer for MVP group, P &amp;gt; 0.05). The number of transferred embryos was (mean ±SD) 1.6±0.5 for both groups, P &amp;gt; 0.05. Furthermore, the number of top-quality embryos (cleavage stage or blastocyst) was also similar, P &amp;gt; 0.05. Moreover, clinical pregnancy (&amp;gt; 12 weeks) was 42% in MVP+DYG group versus 31% in the MVP group (-0.22-1.27, P = 0.156) and the early pregnancy loss per positive hcg test did not differ (18% for MVP+DGY and 22% for MVP, P = 0.687). In addition, we performed a multivariable analysis controlling possible confounders for clinical pregnancy: BMI, age, AMH, embryo quality, infertility aetiology and embryo stage during the transfer, and only age (0.86; 95%CI -0.229 to -0.064, P = 0.001) was related to clinical pregnancy. Limitations, reasons for caution The main limitation is the cohort design of our study, with an inherent risk of bias (selection bias). Moreover, we calculated this study to achieve the power for a non-inferiority comparison, not superiority comparison. Wider implications of the findings This is the first study comparing MVP+DYG to only MVP in patients submitted to FET using the Letrozole-hcg protocol. We demonstrated in this non-inferiority study the usefulness of adding DYG. Moreover, our results were promising showing a trend towards better pregnancy rates after MVP+DYG. Trial registration number not applicable

P-683 Progestins vs flexible GnRH antagonist for LH suppression during controlled ovarian stimulation in POSEIDON groups 3 and 4 patients: Analysis of effectiveness and cycle outcomes

Abstract Study question How do cycle outcomes differ between controlled ovarian stimulations using progestins vs flexible GnRH antagonists for LH suppression in women with diminished ovarian reserve (DOR)? Summary answer While progestin use is associated with significantly higher blastocyst rate than GnRH antagonists in POSEIDON group 4, the latter gives better results in group 3. What is known already Controlled ovarian stimulation (COS) in patients with DOR carries the additional risk of premature luteinizing hormone (LH) surge and ovulation.GnRH antagonists are popular for LH suppression in COS because of their convenient, quicker onset of action, flexibility to use GnRH agonist as a trigger and continue as double stimulation, allowing rapid pooling of embryos. Ease of oral administration, combined with cost-effectiveness and retention of all the benefits of GnRH antagonists makes progestins an attractive alternative to GnRH antagonists for COS in patients with DOR who often need multiple stimulation cycles to enable the pooling of embryos. Study design, size, duration An open-label, multicentric, randomized controlled study was conducted over 1 year from January 2023 to December 2023. 140 women aged 21- 42 years and with AMH &amp;lt;1.2 ng/dl were randomized into 2 groups in a 1:1 ratio, using either oral progestins or GnRH antagonists for LH suppression. The two groups were further comparative analyzed under POSEIDON 3 and 4 subgroups. Those with BMI &amp;gt;40kg/m2 and with partners having severely compromised semen parameters were excluded. Participants/materials, setting, methods In Group A (PPOS): Medroxyprogesterone acetate 10 mg orally was given daily with gonadotropins (hMG 300- 375 IU) from cycle day 2 until trigger. In Group B (Antagonist), patients had daily GnRH antagonist, cetrotide 0.25 mg, subcutaneous administration started when the dominant follicles reached 12-14 mm size during controlled ovarian stimulation. This was continued until the trigger. Following oocyte retrieval and ICSI, embryos were cultured until D5 and vitrified fortransfer in subsequent HRT cycles. Main results and the role of chance Patients in Group A, using PPOS, were noted to have significantly better fertilization rates than those in Group B, using flexible GnRH antagonists (0.82 + 0.2 vs 0.66 + 0.4, p-value &amp;lt;0.01). Though the number of top-quality embryos (TQE) frozen was not significantly different between groups A and B (p-value = 0.44), a significant difference in the outcome was noted when comparatively analyzed under the subgroups of POSEIDON groups 3 and 4. While patients in POSEIDON group 4 got significantly more top-quality embryos (TQE) when progestins were used for LH suppression (1 + 0.11 vs 0.77 + 0.41, p-value &amp;lt;0.01), those in POSEIDON group 3 got significantly more top-quality embryos when GnRH antagonist was used (0.94 vs 2, p-value &amp;lt;0.01). Patients in Group A and B were found to have no significant difference in the following outcomes: incidence of premature LH surge (4.3% vs 7.1%, p value= 0.71), number of days of stimulation (10.26 + 2.18 vs 10.26 +2.94, p value= 0.99), total gonadotropin dosage used (3448.64+ 1007.98 vs 3087.41 + 1260.56, p value=0.06), total number of oocytes retrieved (5.84 + 3.3 vs 4.9 + 3.4, p value=0.09) and total cycle cancellation rate (30.1% vs 35.7%, p value= 0.11). Limitations, reasons for caution The small sample size of the cases limits the current statistical power of the study. The results being encouraging need to be confirmed in a larger patient population and followed for a longer duration to enable calculation of implantation and clinical pregnancy rates for all patients. Wider implications of the findings Oral progestins are an effective and cheaper, patient-friendly alternative to injectable GnRH antagonists during COS in women with DOR. Considering the significantly higher TQEs formed, PPOS can be preferred in older, POSEIDON group 4 patients, whereas flexible GnRH antagonist protocol can be our choice in the younger, POSEIDON group 3. Trial registration number Not applicable

P-286 Comparative study of frozen-thawed embryo transfer with modified natural cycle versus HRT cycle in previously cancelled true natural cycle patients

Abstract Study question Is there any difference in outcome of frozen embryo transfer(FET) between hormone replacement therapy(HRT) and modified natural cycle(MNC) in previously cancelled true natural cycle patients Summary answer In patients with previous history of cancelled true natural cycle, MNC results in higher clinical pregnancy rates after FET, when compared to HRT cycle What is known already Preparation of endometrium lays down the foundation for conception and subsequent successful pregnancy.There has been a plethora of endometrial preparation protocols described in the literature. The established protocols are true natural cycle,MNC with or without luteal phase support(LPS) and HRT cycle with or without gonadotrophin releasing hormone agonist(GnRha) suppression. Nevertheless,there is no consensus on protocol which may provide the best outcome in patients who have had cancelled true natural cycle.In such situations,HRT cycle may be considered as an easy option as the cancellation rate is low.However,HRT treatment is known for higher early pregnancy and obstetric complications,compared to MNC Study design, size, duration Prospective observational study,where 155 patients undergoing FET who had minimum one true natural cycle cancellation were recruited.They were divided into group A undergoing HRT cycle(n = 77) and group B for MNC cycle(n = 78).The study was conducted in a fertility unit over six months from June-November 2023.Primary outcome measures were serum betaHCG estimation and ultrasonographic documentation of intrauterine pregnancy.Results were analysed using statistical software SPSS version25 and p value of less than 0.05 was considered statistically significant Participants/materials, setting, methods HRT patients received injectable GnRha 3.75 mg on day21 of previous cycle.Oral estradiol valerate 6mg daily started on day2 of menses. When ET was minimum 7mm, luteal phase support(LPS) was started with daily oral and vaginal progesterone(30mg and 600mcg respectively),followed by FET. MNC patients received Letrozole 5mg daily from day 2-6 of menstruation.rhCG 250mcg was given subcutaneously,when ET was at least 7mm,dominant follicle 16-18mm and progesterone(P4) less than 1ng/ml.LPS(vaginal progesterone600mcg) was started 36hours after rHCG,followed by FET Main results and the role of chance Mean ET in MNC group was 8.92mm ± SD1.38, which was higher than HRT group (8.31 mm ± SD0.89). This difference was statistically significant with a p value of 0.014.Serum beta HCG estimation was done 2weeks after FET. In HRT group beta HCG was positive in 41 out of 77(53.25%) and in MNC group positivity was higher being 48 out of 78(61.54%). However, this difference was not statistically significant. Transvaginal ultrasonography(TVS) was done to confirm intrauterine pregnancy 2weeks after beta HCG assay. Clinical pregnancy rate(CPR) was higher in MNC group with 32 out of 78(41.03%),compared to 18 out of 77(23.38%) in HRT group. This difference is statistically significant with p value of 0.019 Limitations, reasons for caution Relatively small population in this study may be the reason for caution to interpret the statistical data. Study with higher numbers may bring about more robust conclusions Wider implications of the findings Patients with failed true natural cycles may be considered for modified natural cycle(MNC) stimulation for FET, without attempt of another true natural cycle stimulation Trial registration number NOT APPLICABLE

P-647 Association between PCOS phenotype-D and euploid blastocyst rate per cohort of inseminated oocytes: a matched case-control study versus idiopathic infertile women

Abstract Study question Is there any association between PCOS phenotype-D and oocyte competence defined as euploid blastocyst rate (EBR) per cohort of inseminated oocytes? Summary answer Although higher fertilization and blastulation rates were reported in PCOS phenotype-D women versus idiopathic infertile patients, the EBR per cohort of inseminated oocytes was comparable. What is known already Several studies report poorer oocyte quality and cumulative-live-birth-rate (CLBR) in hyperandrogenic PCOS phenotypes, as defined according to the Rotterdam criteria. Increased androgen concentrations in follicular fluids are indeed associated with elevated serum-LH levels, which can block dominant follicle development inducing atresia and negatively impact fertilization rates and embryo development. Limited evidence exists in phenotype-D PCOS patients, namely women characterized by oligomenorrhea, ovarian PCO morphology and absence of hyperandrogenism. Here, we report the embryological and clinical outcomes in these women during ICSI cycles with preimplantation genetic testing for aneuploidies (PGT-A) at the blastocyst stage. Study design, size, duration Retrospective propensity score matched (PSM) case-control study. Among PGT-A cycles conducted by naïve patients with own oocytes (2013-2021), we excluded FNA/TESE. 58 phenotype-D PCOS patients were identified according to the Rotterdam criteria. These patients were matched for maternal age, number of cumulus-oocyte-complexes (COCs), and sperm quality, with 58 patients with idiopathic infertility, regular cycles, normal ovarian morphology, and no sign of clinical hyperandrogenism. The primary outcome was EBR per cohort of inseminated oocytes. Participants/materials, setting, methods GnRH-antagonist ovarian stimulation, ICSI, blastocyst biopsy, qPCR/NGS-analysis to assess uniform aneuploidies and vitrified-warmed single blastocyst transfers were conducted. The PCOS and control groups were similar for age (35.6±3.0 versus 36.0±3.9 years), COCs (23.1±6.7 versus 23.5±7.6), sperm factor, primary/secondary infertility, hormonal values, BMI (23.8±5.3 versus 22.0±2.8), and duration of infertility (3.6±2.2 versus 3.6±2.0 years). All intermediate embryological and clinical outcomes were assessed as secondary endpoints. Linear/logistic regressions adjusted for confounders were conducted to confirm statistically-significant differences. Main results and the role of chance No difference was reported in maturation rates, but women with PCOS showed better fertilization rates per cohort of inseminated oocytes (76.9±15.2% versus 67.3±20.4%, Mann-Whitney-U-test&amp;lt;0.01), and blastulation rates per cohort of 2PN-zygotes (52±20.4% versus 43.7±20.7%, Mann-Whitney-U-test=0.03). Eventually, PCOS patients obtained more blastocysts than controls (5.8±3.1 versus 4.5±2.9, Mann-Whitney-U-test=0.02), despite similar numbers of metaphase-II oocytes in the groups (16.5±6.1 versus 16.5±7.0). All differences remained significant after adjusting for maternal age and sperm factor. Nevertheless, the euploidy rates per cohort of biopsied blastocysts were similar, thus involving comparable EBR per cohort of inseminated oocytes (21.7±14.1% versus 17.2±16%, Mann-Whitney-U-test=0.12). More patients obtained ≥1 euploid blastocyst in the PCOS versus the control group (N = 56/58, 96% versus N = 47/58, 81%, Fisher’s-exact-test=0.02), independently from maternal age, semen quality, and number of inseminated oocytes (Odds-Ratio: 6.5, 95%CI:1.3-33.7, p = 0.03). Lastly, all clinical outcomes per first vitrified-warmed euploid transfer were similar, thereby involving comparable LBRs (N = 28/54, 51.9% versus N = 26/47, 55.3% in the PCOS and control groups, p = 0.8; Odds-Ratio adjusted for blastocyst quality and day: 1.19, 95%CI:0.5-2.7, p = 0.68). Limitations, reasons for caution Although clinical hyperandrogenism was absent in both groups, biochemical hyperandrogenism was not assessed. Nonetheless, this pilot study paves the way for future more detailed investigations. 24% of cycles in the PCOS group were not concluded, therefore a CLBR comparison would be biased and was not reported. Wider implications of the findings The lower developmental competence in the control group suggests oocyte quality issues, other than chromosomal, underlying their “unexplained infertility” condition. In phenotype-D PCOS women, IVF is effective. Since &amp;gt;50% of this subgroup of women had already failed multiple ovulation-induction and/or intrauterine-insemination attempts, an early referral to IVF deserves further investigations. Trial registration number Not applicable

P-723 Egg-conomized frozen embryo transfer

Abstract Study question Is home-based monitoring of ovulation cost effective compared with hospital-controlled ovulation in women undergoing frozen embryo transfer in the natural cycle? Summary answer Home-based monitoring to time frozen-embryo-transfer is cost-effective compared to hospital-controlled ovulation, as it results in lower cost with no difference in ongoing pregnancy rates. What is known already Women undergoing frozen embryo transfer treated by home-based monitoring of ovulation or hospital-controlled ovulation have comparable ongoing pregnancy rates. We found no differences in secondary outcomes, including the risk of undetected ovulation. Complete home-based monitoring of ovulation with LH hormone kits is feasible and requires no hospital visits at lower costs since ultrasound monitoring and hCG injection are no longer needed. Both consequences imply potentially lower costs after home-based monitoring of ovulation. Study design, size, duration We performed an economic evaluation of home-based monitoring of ovulation compared with hospital-controlled ovulation in a national multicentre randomised controlled trial in women undergoing frozen embryo transfer (ANTARCTICA-2 RCT Dutch TrialRegister Trial NL6414). 1464 women were randomly assigned between April 10, 2018, and April 13, 2022, with 732 allocated to home-based monitoring and 732 to hospital-controlled monitoring. All randomized patients were included according to the intention-to-treat principle. Participants/materials, setting, methods We performed a cost-effectiveness analysis from a hospital and societal perspective. We compared the direct medical costs of home-based monitoring of ovulation and hospital-controlled ovulation during one cycle until an ongoing pregnancy occurred. Direct medical costs included digital ovulation tests, transvaginal ultrasound monitoring of the dominant follicle followed by hCG trigger, hormone measurements in blood, treatment for miscarriage or ectopic pregnancy. Nonparametric bootstrapping was used to calculate cost estimates and differences with 95% confidence intervals. Main results and the role of chance Ongoing pregnancy rates were 20·8% in the home-based monitoring group and 20·9% in the hospital-controlled group (risk ratio [RR] 0·99 [90% CI 0·81 to 1·22]; risk difference [RD] -0·14 [90% CI -3·63 to 3·36]). No differences in ectopic pregnancies or miscarriages were found. Home-based monitoring required less travelling to the hospital, less ultrasounds by doctors or nurses, less hormone measurements in blood, and less medication (hCG injections). Mean direct medical costs per woman in the home-based monitoring of ovulation group and in the hospital-controlled ovulation group were €752 versus €991, respectively, with a mean difference of €239. The ICER consistently showed home-based monitoring to be less costly with no difference in effectiveness. Consequently, the cost difference from a societal perspective was larger. The mean costs per woman in the home-based monitoring of ovulation group and in the hospital-controlled ovulation group were €787 versus €1395, respectively, with a mean difference of €607 in favour of home-based monitoring. Limitations, reasons for caution We report on one cycle per women. Women usually undergomultiple frozen-embryo-cycles. This is of importance for clinical decision making aboutimplementation of home-based monitoring, since the cumulative benefit of multiple cycles perwoman should be taken into account. Wider implications of the findings The results of our trial show that home-based monitoring time frozen embryo transfer is equally effective but less costly compared with hospital-controlled ovulation. In this era of climate change and shortages of hospital staff and waiting lists, any process that takes less human labour is important. Trial registration number Dutch Trial Register (Trial NL6414)

P-646 Prognostic statistical model of age-specific anti-Müllerian hormone (AMH) decrease based on hormone values of 23,528 women

Abstract Study question The analysis of anti-Müllerian (AMH) levels, can a useful statistical model be constructed to predict the rate of decrease of AMH levels at different ages? Summary answer A determination of AMH levels can be an objective marker of a ovarian age and a prognostic marker of the rate of ovarian function decline. What is known already The anti-Müllerian hormone is a dimeric glycoprotein produced by granulosa cells of the antral follicles in the ovaries, and AMH participates in the formation of the dominant follicle during folliculogenesis. Serum AMH levels are relatively constant and show little variability between and within the menstrual cycle. The level of serum AMH is proportional to the number of antral follicles and therefore most suitable for determining ovarian reserve. For this reason, AMH is a convenient marker for the biological age of the ovary and for the response to controlled ovarian stimulation (COS). Study design, size, duration A nationwide cross-sectional retrospective study was conducted between 2017 and 2023 and included 23,528 women the ages of 20 - 50, in which AMH levels were measured once. We performed an analysis of the different AMH levels at different ages and constructed a predictive statistical model for the rate of AMH decline. Results were analyzed in subgroups with AMH values &amp;lt; 1 ng/mL, between 1 and 3,5 ng/mL, and &amp;gt; 3,5 ng/mL, at one-year intervals. Participants/materials, setting, methods All women who visited the laboratory for AMH testing were included in the analysis. The samples were collected in 38 points throughout the country and the analysis was carried out in one centralized laboratory using the Ansh Labs (Webster, TX, USA) manual assays, including the ultra-sensitive AMH enzyme-linked immunosorbent assay (ELISA), with a management range of 0,08 - 14,2 ng/ml. The intra-assay variations were 1,97% and 4,00%. The inter-assay variations were 4,63% and 1,98%, respectively. Main results and the role of chance When analyzing all samples in each consecutive year, we found that the rate of AMH decline was approximately linear and inversely proportional to the woman’s age. However, when analyzing the results for the rate of AMH reduction in the different subgroups, we found out that: In women with AMH &amp;lt; 1 ng/ml, the rate of decline with advancing age changes as follows: until age 34, the decline in AMH is very slow, between ages 35 and 45 there is a rapid acceleration of the process.. In women with AMH between 1 and 3,5 ng/ml, the rate of decline with age was approximately constant. In women with AMH &amp;gt; 3,5 ng/ml, the rate of hormone decline is approximately constant but the year-on-year decline rate is decreasing. Based on our analysis and clinical experience, it is our opinion that the rate of AMH decline for the low AMH group has a non-linear characteristic, while ingeneral different groups exhibit different dynamics for the rate of decline. On this basis, we created a statistical model to predict the decrease in AMH levels at different ages. Limitations, reasons for caution Women of only one ethnicity were included in the study. The studied group is heterogeneous, which does not exclude the inclusion of women with a certain pathology and infertility. In some cases, a single determination of AMH could not predict individual differences in rates of hormone reduction. Wider implications of the findings Determination of reference values for AMH at different ages, based on the large volume of examined samples may facilitate the application of AMH in clinical practice. Based on our statistical analysis, creating a prognostic model for decreasing ovarian function and time to menopause appears feasible. Trial registration number NA

P-588 Serum Luteinizing Hormone levels before progesterone supplementation are significantly associated with live birth rate in single euploid frozen embryo transfers performed in hormonal replacement cycles

Abstract Study question Do luteinizing hormone (LH) levels measured prior to initiating progesterone supplementation influence live birth rate (LBR) in artificial frozen-thawed single euploid blastocyst transfer cycles? Summary answer Serum LH levels, measured prior to progesterone initiation in artificial frozen-thawed single euploid blastocyst transfer cycles, are significantly associated with LBR. What is known already In the absence of a dominant follicle, estrogen supplementation in artificial endometrial preparation for frozen embryo transfer (FRET) can lead to a rise in endogenous LH levels, as observed in a natural cycle. Since the LH rise is a key feature in natural conception and the embryo, the endometrium, and the myometrium display receptors for LH, the rise observed during FRET preparation may have an impact on the clinical outcomes of the treatment. Previous studies found contradictory results hence none of them excluded embryo aneuploidy by implementation of preimplantation genetic testing for aneuploidies and the transfer of euploid embryos. Study design, size, duration Retrospective analysis of 639 frozen-thawed single euploid blastocyst transfer cycles performed in a tertiary referral IVF center from January 2018 to August 2023. Cycles with hormonal pre-treatment or pituitary suppression were excluded. Participants/materials, setting, methods Single euploid FRET cycles were included. Oral estradiol administration commenced on cycle-day 2/3. Estradiol, progesterone, and LH were measured at the start of endometrial preparation and up to 3 days before progesterone initiation, and the slope of LH was calculated. Patients were stratified in groups according to their LH values before progesterone administration, and the impact of LH on LBR and implantation rate was assessed. Logistic regression analysis was performed to adjust for potential confounders. Main results and the role of chance In total 639 cycles were included. Patients’ characteristics (mean+/-SD) were: age 33.2±5.9 years; BMI 27.5±4.9 kg/m2. The median duration of estrogen administration was 15 days (range: 11-27 days). The overall implantation rate and LBR were 65.9% (421/639) and 46.9% (300/639), respectively. Patients were stratified into six groups according to their LH levels prior to progesterone supplementation: &amp;lt;10th percentile (≤6mIU/ml, n = 57), p10th-p25th (&amp;gt;6 to ≤ 8.5mIU/ml, n = 81), p25th-p50th (&amp;gt;8.5 to ≤ 12.4mIU/ml, n = 176), p50th-p75th (&amp;gt;12.4 to ≤ 18.1mIU/ml, n = 180), p75th-p90th (&amp;gt;18.1 to ≤ 25.0mIU/ml, n = 91) and &amp;gt;p90th (&amp;gt;25.0mIU/ml, n = 54). A significant trend for higher LBR with increasing serum LH levels was observed (Cochran-Armitage Test, P = 0.041) but not for implantation rate (P = 0.158). Those with higher basal serum estradiol levels before estrogen supplementation had a steeper LH increase from basal to progesterone-supplementation day (0.40 mIU/mL higher per 10pmol/L increase in basal estradiol, P = 0.027). Regression analysis identified as independent predictors of LBR BMI (OR 0.96, 95%CI: 0.93-0.99) and embryo quality (CC vs. AA p &amp;lt; 0.001, CB vs. AA p = 0.027, BC vs. AA p = 0.013). Patients with steeper LH increases from estrogen to progesterone-supplementation day had higher LBR in both univariable (OR:1.27, 95%CI: 1.00–1.63, P = 0.052) and multivariable analyses (OR:1.26, 95%CI: 0.97–1.64, P = 0.085) but the difference didn’t reach statistical significance. Limitations, reasons for caution The retrospective design of the study is a limitation. Results should be interpreted with caution due to the small number of patients in the lowest and highest LH percentile groups. Wider implications of the findings The results of this study suggest that serum LH levels measured before progesterone supplementation may have an impact on the clinical outcome of artificial frozen-thawed blastocyst transfer cycles. Further studies with a higher sample size are necessary to confirm or refute our findings. Trial registration number not applicable