Recombinant hCG Research Articles

Dual trigger versus human chorionic gonadotropin trigger for blastocyst quality and cumulative live birth.

To evaluate the difference in the number of euploid blastocysts and cumulative live birth rate (LBR) between dual and human chorionic gonadotropin (hCG) triggers in poor and normal ovarian responders undergoing preimplantation genetic testing (PGT) cycles. This retrospective cohort study was enrolled from July 2018 to December 2021 and followed up until June 2024 at a single reproductive medical center. Overall, 1040 in vitro fertilization (IVF)-PGT and 784 frozen-thawed embryo transfer (FET) cycles were assessed. Dual (triptorelin acetate 0.2 mg and recombinant hCG [rhCG] 250 µg) or hCG (rhCG 250 µg) trigger was used for oocyte maturation in the gonadotropin-releasing hormone antagonist protocol and PGT cycles. We assessed the embryo outcomes and FET cumulative pregnancy outcomes. The number of oocytes retrieved (10.17 ± 5.22 vs 10.27 ± 5.14, P = 0.789), MII oocytes (8.24 ± 4.26 vs 8.28 ± 4.05, P = 0.888), blastocysts (2.16 ± 1.50 vs 2.12 ± 1.49, P = 0.729), euploid blastocysts (1.06 ± 1.14 vs 1.09 ± 1.23, P = 0.726), and the rate of cumulative LBR (24.9% vs 24.9%, P = 1.000) in the dual trigger group were comparable with those in the hCG group. The trigger method was not correlated with higher LBR based on logistic regression analysis (odds ratio[OR] = 1.040 [0.778-1.392], P = 0.790). For poor and normal ovarian responders, the dual trigger, compared with the hCG trigger, did not improve the PGT embryo outcomes and FET cumulative pregnancy outcomes.

Evaluation of Jacalin lectin sorbents for the extraction of the human chorionic gonadotropin glycoforms prior to analysis by nano liquid chromatography-high resolution mass spectrometry

Human chorionic gonadotropin (hCG) is a dimeric, highly glycosylated hormone with a total of 4 N- and 4 O-glycosylation sites in its two subunits, hCGα and hCGβ. Recently, we developed a novel nano liquid chromatography coupled to high resolution mass spectrometry (nanoLC-HRMS) method for the analysis and thus the detection of the intact glycoforms of hCG. Here, a sorbent functionalized with the Jacalin lectin was evaluated in solid-phase extraction (SPE) for its potential to fractionate the hCG glycoforms prior to their nanoLC-HRMS analysis at the intact level, which may facilitate the detection of low-abundance glycoforms and may lead to a more detailed characterization of the hormone glycosylation. A commercial sorbent based on Jacalin immobilized on Sepharose and having a lectin density of 4.5mg per ml of gel was selected to carry out SPE and its capacity was estimated to be of some tens of μg of hCG per ml of lectin sorbent. Next, the SPE protocol was modified to improve the extraction recoveries. Especially, it was noticed that an extensive pre-conditioning procedure prior to the first use of a cartridge was necessary to remove the residual non-grafted lectins. Indeed, if on-grafted lectins are not eliminated, they may bind a part of hCG glycoformes preventing they retention by the sorbent, leading to low extraction recoveries (around 10%). With the extensive pre-conditioning procedure, the average extraction recoveries for both hCGα and hCGβ glycoforms were about 50%, with either recombinant or urinary hCG. Qualitatively, the fractionation of hCG glycoforms between the washing and elution fractions was achieved with the urinary hCG sample by determining the number of glycoforms detected in each fraction. It appears that 12 hCGα glycoforms have a low affinity (detected only in the washing fraction), 1 a low-medium affinity (detected in washing and elution 1 fractions), 16 a medium affinity (detected in washing, elution 1 and 2 fractions), and 12 a high affinity (detected only in elution 1 and 2 fractions). For the hCGβ glycoforms, similarly, 3 have a low affinity and 12 a low-medium affinity. Additionally, the 3 hCGβ glycoforms were detected better. A different behavior was observed with the recombinant hCG sample, which indicates glycosylation differences between the two hCG samples. This shows the potential of lectin-based affinity fractionation before nanoLC-HRMS analysis to better characterize the glycosylation state of hCG at the intact level.

Analytical Investigation of the Profile of Human Chorionic Gonadotropin in Highly Purified Human Menopausal Gonadotrophin Preparations.

Highly purified human menopausal gonadotropin (HP-hMG [Menopur®, Ferring Pharmaceuticals, Saint-Prex, Switzerland]) contains a 1:1 ratio of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This analysis aimed to assess gonadotropin (FSH, LH and hCG) abundance in HP-hMG and clarify the source of hCG by assessing the presence of sulfated glycans, which are diagnostic for pituitary hCG forms due to their distinct glycosylation patterns. Additionally, the purity of each sample, their specific components, and their oxidation levels were assessed. HP-hMG samples (three of Menopur® and two of Menogon® Ferring Pharmaceuticals, Saint-Prex, Switzerland) were included in the current analyses. Brevactid® (urinary hCG; Ferring Pharmaceuticals, Saint-Prex, Switzerland) and Ovidrel® (recombinant hCG; Merck KGaA, Darmstadt, Germany) were used as control samples. Glycopeptide mapping and analysis of impurities were carried out by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Oxidation was assessed through reducing peptide mapping using LC-MS/MS. The FSH and LH in the HP-hMG samples showed sulfated glycans, while no signals of sulfated glycopeptides were detected on any site of the beta subunit of hCG. HP-hMG test samples presented the same hCG glycan distribution as the control sample (placental hCG, Brevactid®) extracted from the urine of pregnant women, suggesting a non-pituitary source of hCG. Protein impurities were estimated to constitute approximately 20-30% of the entire HP-hMG protein content in the test samples. More than 200 non-gonadotropin proteins were identified in the HP-hMG test samples, of which several were involved in embryonic development or pregnancy. The alpha subunit of the tested samples was strongly oxidized, with a relative abundance of 20% of the total gonadotropin content. Without taking into account all the protein impurities, the beta subunit of LH was detected only in traces (0.9-1.2%) in all tested HP-HMG samples, confirming the data obtained by intact molecule analysis, while high levels of beta hCG (18-47%) were observed. Advanced molecular analysis of HP-hMG indicates a primarily placental origin of hCG, as evidenced by the absence of hCG sulfated glycans and the predominance of placental non-sulfated hCG in LH activity. The analysis revealed 20-30% of protein impurities and a significant presence of oxidized forms in the HP-hMG samples. These findings are critical for understanding the quality, safety, and clinical profile of HP-hMG.

Low Dose hCG Support in Modified Natural Frozen Embryo Transfer Cycles.

What is the effect of a single low-dose recombinant hCG injection after embryo transfer (ET) in letrozole-induced modified natural frozen embryo transfer cycles (mNC-FET)?. An observational study was conducted in the university-affiliated referral clinic between 2022 and 2024. Women aged 18-42 with at least one vitrified blastocyst obtained from the previous cycle(s) were included. Ovulation induction for endometrial preparation was initiated with oral letrozol (5mg/day) for five days. Ovulation was triggered using 6500IU rec hCG sc when the leading follicle > 17mm, endometrial thickness > 7.5mm, and serum progesterone (P) < 1.5ng/ml. All women received 30mg dydrogesterone/day po for additional five-day luteal support. On the 6th day, ET was performed. Based on a quasi-randomized design, a group of women additionally received a half single bolus of (3250IU) rec hCG (sc) on the morning of 3rd day of ET (hCG group). Women who did not receive additional hCG were assigned as controls.One hundred fifty-four women were detected to be eligible for the study among 2150 initiated FET cycles during the period.Demographic data of the groups, including mean women's age, BMI, serum AMH, and infertility etiologies, were comparable in terms of variables. Mean serum progesterone values and the number of transferred embryos were also similar. A significantly higher ongoing pregnancy/started cycle was documented in the hCG group than in controls (46.7% vs 33.6% respectively, p = 0.03*). A single low-dose hCG injection after ET may improve the OPRs of women in letrozole mNC-FET cycles.

P-703 Is the time interval between triggering final oocyte maturation and oocyte retrieval associated with ART outcomes? A systematic review and meta-analysis

Abstract Study question Is the time interval between triggering final oocyte maturation and oocyte retrieval associated with assisted reproductive technology (ART) outcomes? Summary answer Limited evidence suggests that extending the time interval between triggering final oocyte maturation and oocyte retrieval from 33-36h to 37-41h does not affect ART outcomes. What is known already The time interval between final oocyte maturation and oocyte retrieval varies among IVF centres, although an interval of 33–36 h is the most widely adopted. The use of a prolonged time interval of 37-41h has been suggested to increase the number and competence of oocytes retrieved, their maturation, their ability to be fertilized, their capacity to produce usable embryos and the probability of pregnancy. Considering recently published data, a systematic review is warranted to provide clinicians with updated, evidence-based information regarding the optimal time interval between triggering final oocyte maturation and oocyte retrieval. Study design, size, duration A systematic review and meta-analysis was performed aiming to evaluate the effect of the time interval between triggering final oocyte maturation and oocyte retrieval on ART outcomes. For this purpose, a literature search was carried out until January 2024 in PubMed, MEDLINE and CENTRAL. The primary outcome measure was clinical pregnancy rate, while ovulation before oocyte retrieval, oocytes retrieved, maturation rate, fertilization rate, blastulation rate, implantation rate and miscarriage rate were secondary outcomes. Participants/materials, setting, methods Citation, demographic, methodological and clinical data were extracted from the studies by two independent reviewers. Quality was assessed using the RoB2 Tool by Cochrane. Statistical heterogeneity was assessed by I2. In dichotomous data, estimates were expressed as relative risk (RR) with 95% confidence intervals (CIs), using the fixed or random effects method. In continuous data, differences were pooled across resulting in a weighted mean difference (WMD) with 95% CI. Main results and the role of chance Six eligible RCTs (n = 1081) were identified, published between 1991-2023. In three trials, conventional insemination was used for fertilization, in two trials this was performed by intracytoplasmic sperm injection (ICSI), whereas in one trial either conventional insemination or ICSI were used. The time intervals between triggering final oocyte maturation and oocyte retrieval compared, varied between studies (34.5-36 vs 38.5-40h, 33 vs 41h, 34 vs 38h, 35 vs 37h, 34 vs 39h and 36 vs 38h). Patients were grouped in advance based on these time intervals (short interval group: 33-36h versus long interval group: 37-41h). Ovarian stimulation was performed with GnRH analogues (GnRH antagonists:1 GnRH agonists:5) and gonadotrophins (HMG:4 recombinant FSH:2, while triggering of final oocyte maturation was performed with hCG( recombinant hCG:1 urinary hCG:5). None of the studies was deemed as of low risk of bias. No statistically significant differences were observed between the short nd long interval groups regarding clinical pregnancy rate per randomized patient (RR: 0.83; 95%CI: 0.62-1.11; fixed effects model; heterogeneity: I2:36.4%; five studies, 827 patients). Furthermore, it was not feasible to pool any of the secondary outcome data. This was either because they were not reported, or due to the fact that they were reported inappropriately. Limitations, reasons for caution This meta-analysis included a limited number of RCTs, which were generally of low quality due to methodological limitations and of high risk of bias. Moreover, the total number of patients is still not large enough to draw solid conclusions. Wider implications of the findings Taking into account the limitations of the current meta-analysis, it appears that clinicians may elect a shorter (33–36 h) or a longer (37-41h) interval regarding the timing of oocyte retrieval following triggering final oocyte maturation, without affecting clinical pregnancy rate. Trial registration number PROSPERO: CRD42024501986

Assessment of active translation in cumulus-enclosed and denuded oocytes during standard in vitro maturation and early embryo development.

Which actively translated maternal transcripts are differentially regulated between clinically relevant in vitro and in vivo maturation (IVM) conditions in mouse oocytes and zygotes? Our findings uncovered significant differences in the global transcriptome as well as alterations in the translation of specific transcripts encoding components of energy production, cell cycle regulation, and protein synthesis in oocytes and RNA metabolism in zygotes. Properly regulated translation of stored maternal transcripts is a crucial factor for successful development of oocytes and early embryos, particularly due to the transcriptionally silent phase of meiosis. This is a basic science study utilizing an ICR mouse model, best suited for studying in vivo maturation. In the treatment group, fully grown germinal vesicle oocytes from stimulated ovaries were in vitro matured to the metaphase II (MII) stage either as denuded without gonadotropins (IVM DO), or as cumulus-oocyte complexes (IVM COC) in the presence of 0.075 IU/ml recombinant FSH (rFSH) and 0.075 IU/ml recombinant hCG (rhCG). To account for changes in developmental competence, IVM COC from non-stimulated ovaries (IVM COC-) were included. In vivo matured MII oocytes (IVO) from stimulated ovaries were used as a control after ovulation triggering with rhCG. To simulate standard IVM conditions, we supplemented media with amino acids, vitamins, and bovine serum albumin. Accordingly, in vitro pronuclear zygotes (IMZ) were generated by IVF from IVM DO, and were compared to in vivo pronuclear zygotes (IVZ). All experiments were performed in quadruplicates with samples collected for both polyribosome fractionation and total transcriptome analysis. Samples were collected over three consecutive months. All ICR mice were bred under legal permission for animal experimentation (no. MZE-24154/2021-18134) obtained from the Ministry of Agriculture of the Czech Republic. Actively translated (polyribosome occupied) maternal transcripts were detected in in vitro and in vivo matured mouse oocytes and zygotes by density gradient ultracentrifugation, followed by RNA isolation and high-throughput RNA sequencing. Bioinformatic analysis was performed and subsequent data validation was done by western blotting, radioactive isotope, and mitotracker dye labelling. Gene expression analysis of acquired polysome-derived high-throughput RNA sequencing data revealed significant changes (RPKM ≥ 0.2; P ≤ 0.005) in translation between in vitro and in vivo matured oocytes and respectively produced pronuclear zygotes. Surprisingly, the comparison between IVM DO and IVM COC RNA-seq data of both fractionated and total transcriptome showed very few transcripts with more than a 2-fold difference. Data validation by radioactive isotope labelling revealed a decrease in global translation bof20% in IVM DO and COC samples in comparison to IVO samples. Moreover, IVM conditions compromised oocyte energy metabolism, which was demonstrated by both changes in polysome recruitment of each of 13 mt-protein-coding transcripts as well as by validation using mitotracker red staining. The data discussed in this publication have been deposited in NCBI's Gene Expression Omnibus and are accessible through GEO Series accession number GSE241633 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE241633). It is extremely complicated to achieve in vivo consistency in animal model systems such as porcine or bovine. To achieve a high reproducibility of in vivo stimulations, the ICR mouse model was selected. However, careful interpretation of our findings with regard to assisted reproductive techniques has to be made by taking into consideration intra-species differences between the mouse model and humans. Also, the sole effect of the cumulus cells' contribution could not be adequately addressed by comparing IVM COC and IVM DO, because the IVM DO were matured without gonadotropin supplementation. Our findings confirmed the inferiority of standard IVM technology compared with the in vivo approach. It also pointed at compromised biological processes employed in the critical translational regulation of in vitro matured MII oocytes and pronuclear zygotes. By highlighting the importance of proper translational regulation during in vitro oocyte maturation, this study should prompt further clinical investigations in the context of translation. This work was supported by the Czech Grant Agency (22-27301S), Charles University Grant Agency (372621), Ministry of Education, Youth and Sports (EXCELLENCE CZ.02.1.01/0.0/0.0/15_003/0000460 OP RDE), and Institutional Research Concept RVO67985904. No competing interest is declared.

Reproductive outcomes of dual trigger therapy with GnRH agonist and hCG versus hCG trigger in women with diminished ovarian reserve: a retrospective study

BackgroundDiminished ovarian reserve (DOR) is one of the obstacles affecting the reproductive outcomes of patients receiving assisted reproductive therapy. The purpose of this study was to investigate whether dual trigger, including gonadotropin‐releasing hormone agonist (GnRHa) and human chorionic gonadotropin (hCG), can improve pregnancy outcomes in patients with DOR undergoing in vitro fertilization (IVF) cycles using mild stimulation protocols.MethodsA total of 734 patients with DOR were included in this retrospective study. Patients were divided into a recombinant hCG trigger group and a dual trigger group (hCG combined with GnRHa) according to the different trigger drugs used. The main outcome measures included the number of oocytes retrieved, the fertilization rate, the number of transferable embryos, the implantation rate, the clinical pregnancy rate, the miscarriage rate, the live birth rate (LBR), and the cumulative live birth rate (CLBR). Generalized linear model and logistic regression analyses were performed for confounding factors.ResultsThere were 337 cycles with a single hCG trigger and 397 cycles with dual trigger. The dual trigger group demonstrated significantly higher numbers of retrieved oocytes [3.60 vs. 2.39, adjusted β = 0.538 (0.221–0.855)], fertilized oocytes [2.55 vs. 1.94, adjusted β = 0.277 (0.031–0.523)] and transferable embryos [1.22 vs. 0.95, adjusted β = 0.162 (-0.005–0.329)] than did the hCG trigger group, whereas no significant difference in the fertilization rate was observed between the two groups. Moreover, the embryo transfer cancellation rate (35.5% vs. 43.9%) was obviously lower in the dual trigger group. Among the fresh embryo transfer cycles, the implantation rate, clinical pregnancy rate, miscarriage rate and live birth rate were similar between the two groups. After controlling for potential confounding variables, the trigger method was identified as an independent factor affecting the number of oocytes retrieved but had no significant impact on the CLBR.ConclusionsDual triggering of final oocyte maturation with hCG combined with GnRHa can significantly increase the number of oocytes retrieved in patients with DOR but has no improvement effect on the implantation rate, clinical pregnancy rate or LBR of fresh cycles or on the CLBR.

#86 : Use of Triptorelin Versus Human Chorionic Gonadotropin as Ovulation Trigger

Background and Aims: Gonadotropin releasing hormone agonist (GnRH-a) trigger has been shown to be associated with significantly lower risk of moderate or severe ovarian hyperstimulation syndrome (OHSS) when compared among women at high risk of OHSS. However, trigger failure has been shown to occur in 2% of cycles using GnRH-a as trigger. This study aims to review the use of GnRH-a as ovulation trigger. Method: Retrospective review of records in antagonist cycles from an ART unit in a tertiary hospital from 2017-2021 was performed. Follicles were considered mature when they reach [Formula: see text] 15 mm. Ovulation triggered with urinary human chorionic gonadotropin (uhCG) (5000-10000 IU), recombinant hCG (rhCG) 250 mcg, or triptorelin 0.2 mg when there were [Formula: see text] 3 mature follicles. All embryos obtained from cycles using triptorelin were cryopreserved. Outcome including the number of oocytes retrieved, the follicle to oocyte index, ovarian hyperstimulation syndrome were reviewed. Results: 1378 cycles were included. 1089 cycles had uhCG or rhCG as trigger, while 284 cycles had triptorelin as trigger. Women in the triptorelin group were significantly younger with a lower basal follicle stimulating hormone level and a higher antral follicle count (Table 1). In the triptorelin group, the total number of mature sized follicles, estrogen level at trigger, oocytes retrieved, number of blastocysts were significantly higher compared to the hCG group (Table 2). Follicle to oocyte index was significantly higher in the triptorelin group but the proportion of mature oocytes were similar in both groups. There were no cases of trigger failure and OHSS in the triptorelin group, but 30 cases of OHSS, with18 cases early onset, 12 cases late onset, amongst them 10 cases (1%) were severe OHSS) in the hCG group. Conclusion: GnRH-a trigger is a good candidate as ovulatory trigger in women at risk of OHSS without hampering the laboratory outcome.

Post-trigger luteinizing hormone concentration to positively predict oocyte yield in the antagonist protocol and its association with genetic variants of LHCGR

BackgroundThe concentration of human chorionic gonadotropin (hCG)/ luteinizing hormone (LH) after triggering is generally accepted as a predictor of the normal ovarian response to the trigger, but few studies have explored the distribution model of concentration and its impact on oocyte yield. Genetic variations in LHCGR, known as a receptor for hCG and LH, also play a role in oocyte maturation and retrieval. The objective of the study was to investigate the impact of concentrations of hCG/LH after triggering on oocyte yield and its association with genetic variants of LHCGR.MethodsA retrospective cohort study including 372 antagonist IVF cycles, in which 205 received the recombinant hCG trigger and 167 received the gonadotropin-releasing hormone agonist (GnRH-a) trigger, was conducted. The post-trigger concentrations of hCG/LH and the LHCGR N312S (rs2293275) genotype were evaluated in patients to analyse the impact of these factors on oocyte yield.ResultsThe oocyte retrieval rate (ORR) increased significantly among the low-, medium- and high-hCG-concentration groups (0.91 ± 0.25, 0.99 ± 0.23 and 1.08 ± 0.19, P < 0.001) and among the low-, medium- and high-LH-concentration groups (0.80 ± 0.29, 0.95 ± 0.21 and 1.07 ± 0.19, P < 0.001). The Pearson correlation coefficient between the post-trigger hCG concentration and ORR was 0.242 (P < 0.001), and that between the LH concentration and ORR was 0.454 (P < 0.001). After adjustment for confounding factors, high post-trigger LH concentrations remained associated with the significantly higher ORRs (adjusted R2 = 0.541, P < 0.001). Patients with the AG genotype of LHCGR N312S were more likely to have low post-trigger LH concentrations (46.10 IU/L versus 60.91 IU/L, P < 0.001) and a significantly lower ORR (0.85 versus 0.96, P = 0.042) than patients with the GG genotype after the GnRH-a trigger.ConclusionsThe post-trigger LH concentration can positively predict oocyte yield in antagonist IVF cycles, and patients with the AG genotype of LHCGR rs2293275 could have a suboptimal oocyte yield using the GnRH-a trigger.

A semi-automated hybrid HPLC-MS approach for in-depth characterization of intact non-covalent heterodimer glycoforms of gonadotropin biopharmaceuticals

BackgroundGonadotropins are a class of heavily glycosylated protein hormones, thus extremely challenging to characterize by mass spectrometry. As biopharmaceuticals, gonadotropins are prescribed for the treatment of infertility and are derived from different sources: either from pooled urine of pregnant women or upon production in genetically modified Chinese Hamster Ovary cells. Human chorionic gonadotropin (hCG) is sold as a biopharmaceutical under the name Pregnyl® (urinary hCG, u-hCG) and Ovitrelle® (recombinant hCG, r-hCG), and recombinant human follicle stimulating hormone (r-hFSH) is marketed as Gonal-f®. Recently, we reported the exhaustive characterization of r-hCG at different structural levels. ResultsWe implement size exclusion (SE) HPLC-MS to automatize the acquisition of native mass spectra of r-hCG dimer, but also u-hCG and r-hFSH, comparing the drug products up to intact heterodimer level. A hybrid HPLC-MS approach was employed for the characterization of r-hCG, u-hCG and r-hFSH drug products at different structural levels. Released glycans were analyzed by porous graphitized carbon (PGC)-HPLC-MS/MS, glycopeptides by reversed-phase (RP)-HPLC-MS/MS, subunits by RP-HPLC-MS and finally the intact native heterodimers by semi-automated online buffer exchange SE-HPLC-MS. The data were integrated using bioinformatic tools, to finally unravel the composition of 1481 co-existing dimeric glycoforms for r-hCG, 1167 glycoforms for u-hCG, and 1440 glycoforms for r-hFSH, and to compare critical quality attributes of the different drug products such as their degree of sialylation and O-glycosylation. Significance and noveltyThe strong alliance of bioanalytics and bioinformatics data integration at the different structural levels allowed the identification of more than thousand different glycoforms of r-hCG, u-hCG, and r-hFSH. The results showed that these biopharmaceuticals differ considerably in their glycosylation patterns and highlight the importance of in-depth characterization of biopharmaceuticals for quality control.© 2017 Elsevier Inc. All rights reserved.

Androgen and inhibin B levels during ovarian stimulation before and after 8 weeks of low-dose hCG priming in women with low ovarian reserve.

Does 8 weeks of daily low-dose hCG administration affect androgen or inhibin B levels in serum and/or follicular fluid (FF) during the subsequent IVF/ICSI cycle in women with low ovarian reserve? Androgen levels in serum and FF, and inhibin B levels in serum, decreased following 8 weeks of hCG administration. Recently, we showed that 8 weeks of low-dose hCG priming, in between two IVF/ICSI treatments in women with poor ovarian responder (anti-Müllerian hormone (AMH) <6.29 pmol/l), resulted in more follicles of 2-5 mm and less of 6-10-mm diameter at the start of stimulation and more retrieved oocytes at oocyte retrieval. The duration of stimulation and total FSH consumption was increased in the IVF/ICSI cycle after priming. Hypothetically, hCG priming stimulates intraovarian androgen synthesis causing upregulation of FSH receptors (FSHR) on granulosa cells. It was therefore unexpected that antral follicles were smaller and the stimulation time longer after hCG priming. This might indicate a different mechanism of action than previously suggested. Blood samples were drawn on stimulation day 1, stimulation days 5-6, trigger day, day of oocyte retrieval, and oocyte retrieval + 5 days in the IVF/ICSI cycles before and after hCG priming (the control and study cycles, respectively). FF was collected from the first aspirated follicle on both sides during oocyte retrieval in both cycles. The study was conducted as a prospective, paired, non-blinded, single-center study conducted between January 2021 and July 2021 at a tertiary care center. The 20 participants underwent two identical IVF/ICSI treatments: a control cycle including elective freezing of all blastocysts and a study cycle with fresh blastocyst transfer. The control and study cycles were separated by 8 weeks (two menstrual cycles) of hCG priming by daily injections of 260 IU recombinant hCG. Women aged 18-40 years with cycle lengths of 23-35 days and AMH <6.29 pmol/l were included. Control and study IVF/ICSI cycles were performed in a fixed GnRH-antagonist protocol. Inhibin B was lower on stimulation day 1 after hCG priming (P = 0.05). Dehydroepiandrosterone sulfate (DHEAS) was significantly lower on stimulation day 1 (P = 0.03), and DHEAS and androstenedione were significantly lower on stimulation days 5-6 after priming (P = 0.02 and P = 0.02) The testosterone level in FF was significantly lower in the study cycle (P = 0.008), while the concentrations of inhibin B and androstenedione in the FF did not differ between the study and control cycles. A lower serum inhibin B in the study cycle corresponds with the antral follicles being significantly smaller after priming, and this probably led to a longer stimulation time in the study cycle. This contradicts the theory that hCG priming increases the intraovarian androgen level, which in turn causes more FSHR on developing (antral up to preovulatory) follicles. However, based on this study, we cannot rule out that an increased intra-follicular androgen level was present at initiation of the ovarian stimulation, without elevating the androgen level in serum and that an increased androgen level may have rescued some small antral follicles that would have otherwise undergone atresia by the end of the previous menstrual cycle. We retrieved significantly more oocytes in the Study cycle, and the production of estradiol per follicle ≥10-mm diameter on trigger day was comparable in the study and control cycles, suggesting that the rescued follicles were competent in terms of producing oocytes and steroid hormones. The sample size was small, and the study was not randomized. Our study design did not allow for the measurement and comparison of androgen levels or FSHR expression in small antral follicles before and immediately after the hCG-priming period. The results make us question the mechanism of action behind hCG priming prior to IVF. It is important to design a study with the puncture of small antral follicles before and immediately after priming to investigate the proposed hypothesis. Improved cycle outcomes, i.e. more retrieved oocytes, must be confirmed in a larger, preferably randomized study. This study was funded by an unrestricted grant from Gedeon Richter awarded to the institution. A.P. reports personal consulting fees from PregLem SA, Novo Nordisk A/S, Ferring Pharmaceuticals A/S, Gedeon Richter Nordics AB, Cryos International, and Merck A/S outside the submitted work and payment or honoraria for lectures from Gedeon Richter Nordics AB, Ferring Pharmaceuticals A/S, Merck A/S, and Theramex and Organon & Co and payment for participation in an advisory board for Preglem. Grants to the institution have been provided by Gedeon Richter Nordics AB, Ferring Pharmaceuticals A/S, and Merck A/S, and equipment and travel support has been given to the institution by Gedeon Richter Nordics AB. The remaining authors have no conflicts of interest to declare. ClinicalTrials.gov Identifier: NCT04643925.

P-657 Elecys anti-Müllerian hormone thresholds for defining ovarian response categories; comparison of published and novel values in 7,988 treatment naïve women

Abstract Study question Test the accuracy of published and novel AMH thresholds in predicting (low, sub-optimal, optimal and high) ovarian response categories in first treatment cycles. Summary answer Published AMH thresholds for poor and excessive ovarian response perform adequately, however, prediction of suboptimal or optimal oocyte yields is difficult reflecting their limited range. What is known already AMH is an established predictor of ovarian response, and can identify women at risk of poor (&amp;lt;4 oocytes) or excessive (&amp;gt;15 oocytes) response. With the development of suboptimal (4 to 9 oocytes) and optimal (10 to 14 oocytes) response categories, a series of AMH ranges for the Roche Elcesys AMH assay has been proposed to predict response for all four categories (AMH &amp;lt;6.4pmol/l, 4.9–11.3 pmol/l, 11.3–20.9 pmol/l, and &amp;gt;14.2 pmol/l). To date there has been no internal or external validation of these single centre derived thresholds, and it is unknown whether they are generalisable to other clinic populations. Study design, size, duration Observational cohort study from 8 UK clinics, incorporating 7,998 women undertaking their first ovarian stimulation cycle for assisted conception or fertility preservation between 2016 and 2022, with a pre-treatment AMH measured using the Roche Elecsys AMH assay. Both GnRH agonist and antagonist cycles were included, with triggering by either recombinant hCG or GnRH agonist once 3 follicles were ³18mm in size with oocyte retrieval performed 36h later. Participants/materials, setting, methods To give equal opportunity to the published and novel thresholds, patients were divided into training (5,330) and testing (2,668) sets. Novel cut-off points for a low, sub-optimal, optimal and high response were derived in the training set. The performance of these novel thresholds and those of published values were then assessed and compared in the testing set by their respective AUC, and precision as defined as the fraction of correct predictions for a certain class. Main results and the role of chance Baseline patient characteristics (mean, SD) were 35.1±4.7 years; BMI 25.5±4.4 kg/m2, with a median AMH 15.2 pmol/l (IQR 8, 26) and a median of 11 (IQR 6,16) oocytes retrieved. These baseline characteristics and outcomes were similar after splitting in the training and testing datasets. Baseline AMH and oocytes collected were moderately correlated (r = 0.54, p &amp;lt; 0.001). 465 (5.8%) cycles were cancelled due to not meeting trigger criteria and classed as poor/low responders. The novel thresholds for low oocyte yield (≤10.05 pmol/l) provided similar performance (AUC 0.70 95%CI 0.66-0.74, sensitivity 0.69, specificity 0.74) to the published thresholds (AUC 0.67, 95%CI 0.62-0.72) in the testing population. Similarly, the novel high (15.9pmol/l) threshold (AUC 0.78, 95%CI 0.75-0.81, sensitivity 0.78, specificity 0.64) exhibited similar performance to the published threshold AUC 0.77, 95%CI 0.74,0.81) in the testing population. Deriving novel thresholds for prediction of 4 categories of response (6.7, 12.9, 18.9pmol) was associated with slightly better precision for low, suboptimal and high categories (p &amp;lt; 0.001), with the fraction of correct predictions for a certain category of response for the novel cut-points; 69.0 % low, 11.7% suboptimal, 14.1% optimal and 78.3% high, as compared to 52.0%, 27.8%, 12.9% and 83.8% respectively for the published values. Limitations, reasons for caution While designing the ovarian stimulation strategies clinicians were aware of the baseline AMH and targeted a perceived optimal response for cumulative live birth (∼15 oocytes), which may have contributed to the performance of both the established and novel AMH thresholds. Wider implications of the findings In a large heterogenous population of women undergoing their first treatment cycle, we confirm the appropriateness of the previously published Elecsys AMH values for prediction of low (&amp;lt;6.4pmol/l) and high (&amp;gt;14.2pmol/l) oocyte yields. Trial registration number N/A

P-671 Comparing clomiphene citrate/ flexible GnRH antagonist vs ultrashort flare GnRH agonist protocols for controlled ovarian stimulation in poor ovarian reserve patients

Abstract Study question How do Clomiphene citrate (CC)/ flexible GnRH antagonist and ultrashort flare GnRH agonist protocols compare in poor ovarian reserve patients (POSEIDON groups 3 &amp; 4)? Summary answer In poor ovarian reserve patients, irrespective of age, use of CC / flexible antagonist vs ultrashort flare protocol significantly reduces gonadotrophin consumption and stimulation duration. What is known already Poor responders constitute 47% of ART patients and up to 65% of these have diminished ovarian reserve. Despite the various treatment options available, lack of good quality evidence to enable recommendation of a particular protocol or adjuvant continues to pose a challenge to their effective management. The need for multiple stimulations for pooling up embryos also makes effective cost of treatment an added concern in them. Study design, size, duration An open label, multi centric, randomized controlled study was conducted over a period of 1 year recruiting 116 women having AMH &amp;lt;1.2ng/dl and antral follicle count (AFC) &amp;lt;5 who were further analysed in POSEIDON 3 and 4 subgroups. Patients were randomized to 1 of 2 groups for controlled ovarian stimulation. Those with severe endometriosis, adenomyosis, autoimmune or metabolic disorders, sustained hyperprolactinaemia, congenital uterine malformations and with male partners having severe oligoasthenoteratozoospermia were excluded. Participants/materials, setting, methods Group A (55 women) received CC 100mg from D1-D5 with 300 IU human menopausal gonadotrophin (hMG) in a flexible GnRH antagonist protocol. Group B (61 women) underwent ultrashort flare protocol. 1mg leuprolide was administered from D1-D4 and 300 IU hMG given D2 onwards followed by flexible GnRH antagonist administration. Dual trigger with triptorelin and recombinant hCG was administered 35-36 hours before oocyte retrieval. Embryos cultured till D5 were vitrified for transfer at a later stage. Main results and the role of chance The two groups were well matched for baseline characteristics like age, BMI, AMH, duration of infertility, D2 AFC, estradiol and FSH levels. The mean total gonadotrophin consumption (3387.29 + 1082.5 vs 4407 + 1224.2, p value &amp;lt;0.01) and the duration of stimulation (10.71 + 2.52 vs 11.95 + 2.43, p value &amp;lt;0.01) were significantly lower in group A vs group B. The primary outcomes of median number of oocytes retrieved (4 vs 4, p value- 0.71) , M2 rate (3 vs 3, p value-0.91), fertilisation rate were similar in the two groups. The secondary outcomes of oocyte retrieval rate (103.05 + 42.97 vs 97.14 + 42.96, p value- 0.63), FORT (0.81 +0.68 vs 0.96 + 0.48, p value- 0.37) FOI (0.91 + 0.55 vs 0.92+ 0.54, p value 0.92), top quality embryo rate (0.53 + 1.1 vs 0.41 + 0.84, p value 0.61), cycle cancellation rate (26.22% vs 29.09%), implantation rate (23.63% vs 24.59%) and clinical pregnancy rate (21.31% vs 20%) were also similar in group A vs B respectively. A subgroup analysis of POSEIDON 3 versus POSEIDON 4 patients revealed similar outcomes with both the protocols in the two groups. Limitations, reasons for caution Small sample size of the cases limits the current statistical power of the study. Wider implications of the findings CC /flexible GnRH antagonist protocol is an effective alternative to ultrashort flare protocol in patients with poor ovarian reserve irrespective of their age. The lower gonadotrophin dosage required and shorter duration of stimulation observed make it a viable option in patients who might need multiple stimulations for pooling up embryos. Trial registration number Not applicable

P-694 Desogestrel did not affect Follicular Output Rate (FORT) during controlled ovarian stimulation for oocyte vitrification: prospective cohort study

Abstract Study question Does desogestrel an option for LH suppression during controlled ovarian stimulation for oocyte vitrification? Summary answer This new option for LH suppression did not affect FORT and, consequently, the number of collected oocytes for vitrification. What is known already Traditionally, LH suppression is achieved by using a gonadotropin-releasing hormone (GnRH) analogue. However, improved cryopreservation techniques and freeze-all strategies are introducing new concepts, including the possibility of using progesterone instead of GnRH analogues. Progesterone compounds are currently wide-used during ovarian stimulation for oocyte freezing for LH suppression. The use of oral medroxyprogesterone was previously shown to effectively prevent the LH surge, without impacting embryo development or pregnancy rates after frozen embryo transfer. The use of dydrogesterone with the same purpose was also effective. Desogestrel is a progesterone broadly known and accepted, and has good tolerability and low cost. Study design, size, duration A prospective cohort study was performed during the period of 2019-2021 including 75 patients submitted to oocyte freezing and 173 women matched by age as the controls (patients submitted to IVF for the first time). Participants/materials, setting, methods Patients from the control group used a flexible GnRH antagonist for LH suppression, and patients in the desogestrel group utilized desogestrel 75 mcg oral twice a day (starting from the beginning of gonadotropin to hCG/agonist day). All patients received the same gonadotropin regimen (recombinant FSH). The final oocyte maturation was equal for both groups (recombinant hCG and GnRH analogue agonist). The primary endpoint was the antral follicle responsiveness to follicle-stimulating hormone, measured by FORT. Main results and the role of chance Age [control group= 36 years (median 28-45); desogestrel group= 36 years (median 23-43); p = 0.793; Mann Whitney U test], baseline antral follicle count [control group= 8 (2-23); desogestrel group= 9 (2-21); p = 0.741; Mann Whitney U test] and anti-Mullerian hormone [control group= 1.5 (0.05-7.95); desogestrel group= 1.00 (0.01-16.00); p = 0.540; Mann Whitney U test] were similar between both groups. However, the controlled ovarian stimulation length was shorter in the control group [10.4±1.6 vs. 11.0±1.6; p = 0.044; t-student test,] and those patients utilized less gonadotropin than the desogestrel group [2736 UI ± 745 vs. 2933 UI ± 785; p = 0.047; t-student test,]. Finally, Follicular Output Rate (FORT) [control group= 45%; desogestrel group= 52%; p = 0.217; t-student test], number of collected oocytes [control group= 6 (1-33); desogestrel group= 8 (1-20); p = 0.293; Mann Whitney U test] and MII [control group= 5 (1-27); desogestrel group= 6 (1-19); p = 0.156, Mann Whitney U test] were the same between both groups. Limitations, reasons for caution The small sample size and the absence of randomization are the main limitations of our study. Since the first results were encouraging, a randomized study should be performed. Wider implications of the findings Desogestrel is a cheap and easy option to be used during controlled ovarian stimulation for oocyte vitrification, since the final results are the same. This is the first scientific report showing the use of desogestrel did not affect FORT and, consequently, the number of collected oocytes for vitrification. Trial registration number Not applicable

P-374 Impact of different luteal phase support protocols in fresh embryo transfers on perinatal outcomes of singleton in vitro fertilization pregnancies: a three-decade experience.

Abstract Study question How can stimulation of corpus luteum in the luteal phase with human chorionic gonadotropin (hCG) improve obstetric and perinatal outcomes? Summary answer There is currently no evidence that the use of hCG as an alternative treatment for luteal-phase support (LPS) improves obstetric and perinatal outcomes. What is known already There are different approaches for providing LPS, although none have shown differences in pregnancy rates. However, emerging evidence has also revealed the important role of corpus luteum in obstetric and perinatal outcomes after in vitro fertilization (IVF) (preeclampsia or intrauterine growth restriction, among others) in the production of progesterone (can be administered exogenously) as well as the secretion of multiple vasoactive active substances. Study design, size, duration We performed a retrospective, single centre study between 1991-2021. A total of 2592 singleton pregnancies were analysed after fresh embryo-transfer according to LPS. Participants/materials, setting, methods IVF singleton pregnancies were stratified into two cohorts according to the LPS protocol: 1) trigger with 5000 IU urinary hCG (U-hCG) and LPS protocol with progesterone 200 mg x3/day/vaginally beginning the day after oocyte retrieval and one u-hCG bolus of 2500 IU, the day and 3 days after oocyte retrieval; and 2) trigger with 250 µgr of recombinant hCG and LPS protocol with only progesterone (200 mg x3/day/ vaginally). Main results and the role of chance We compared the reproductive outcomes between cycles in cohort 1) n = 527 and cohort 2) n = 2065. The two cohorts were stratified and analysed in three groups according to maternal age to reduce possible bias: 35 years old or less, between 36 and 39 years old, and 40 or more years old. In cohort 1, all the cycles followed a long agonist GnRH protocol, while in cohort 2, 78.11% received an agonist GnRH protocol and 21.89 % a GnRH antagonist protocol. Recombinant gonadotropins for ovarian stimulation was administered in all cycles. We observed a greater number of eutocic deliveries, a lower number of instrumentalized births and a stable caesarean rate along the study period. There were no statistical differences between the two treatment groups regarding hypertensive pregnancy disorders, intrauterine growth restriction, small for gestational age or large for gestational age. Group 2 showed an apparent greater tendency, albeit not significant, to preeclampsia and a significant increase in very preterm birth. Emerging evidence has also revealed the important role of corpus luteum in obstetric and perinatal outcomes following IVF. Limitations, reasons for caution The large number of pregnancies evaluated is a clear strength of this study. This is the first series comparing different perinatal outcomes according to LPS. In contrast, the retrospective design and long time period involving changes in laboratory and patient profiles is a clear limitation. Wider implications of the findings The optimization of IVF treatments is especially important and is related to multiple factors, including the individualization of treatments to ensure the safety of IVF treatment as well as that of the pregnancies derived thereof. More studies on the different LPS protocols available are needed. Trial registration number not applicable

Management Outcomes in Males With Hypogonadotropic Hypogonadism Treated With Gonadotropins.

Background Hypogonadotropic hypogonadism is an important cause of male infertility and loss of secondary sexual characteristics. Gonadotropin replacement is mandatory for sexual function, bone health, and normal psychological status. This study is to compare the effectiveness of different gonadotropin therapy modalities in the management of male hypogonadism. Methods A randomized open-label prospective study of 51 patients attended the Faiha Specialized Diabetes, Endocrine and Metabolism Center (FDEMC) with hypogonadotropic hypogonadism, divided randomly into three groups. The first group was treated with human chorionic gonadotropin (hCG) alone, the second group was treated with a combination of both hCG and human menopausal gonadotropin (HMG), while the third group started with hCG alone then followed by combination therapy after six months. Results All modalities of therapy result in a significant increase in mean testicular volume although no clinically significant difference between the groups, but the combination group had the highest increment. The increment in serum testosterone level was statistically significant among the different groups of treatment (p-value < 0.0001). When comparing groups, a higher mean maximum testosterone level (710.4±102.7 ng/dL) was obtained with the combination group followed by the sequential group, with mean maximum testosterone levels (636.0±68.6 ng/dL) (p-value = 0.031). Factors negatively affecting testosterone level include BMI > 30 kg/m2, initial testicular volume < 5 mL, and duration of therapy < 13 months. Conclusions Induction of puberty using recombinant hCG alone is sufficient to induce secondary sexual characteristics, while for fertility issues combination from the start or sequential therapy has better for spermatogenesis. There was no effect of prior exogenous testosterone treatment on final spermatogenesis.

Characterization of beta subunit variants of recombinant human chorionic gonadotrophin

Human chorionic gonadotropin (hCG), an endogenous glycoprotein hormone, has been widely used for the treatment of infertility and corpus luteum defect in women. The biological specificity of hCG is essentially determined by its beta (β-) subunit, whereas the alpha (α-) subunit is a common subunit shared among the gonadotropin family. In development of a therapeutic recombinant hCG, the purity analysis showed that the beta (β-) subunit has two variants, β1 and β2. Structural characterization using a combination of analytical techniques has demonstrated that β1-subunit is derived from non-glycosylation at Asn 13, whereas β2-subunit is a normal species with complete N-glycosylation at both Asn 13 and Asn 30. In vivo Bioactivity evaluation of the r-hCG fractions with various ratios of β1-and β2-subunits showed that incomplete glycosylation at Asn 13 potentially reduced the biological activity of r-hCG to promote uterus growth. Although hCG has a long history of medicinal use, this is the first report to identify the structural difference of hCG β-subunit variants, as well as to preliminary establish the structure-activity relationship of this variation. The obtained results also suggest the importance of variant characterization and necessary quality control of product variants during the development of recombinant protein therapeutics.

Eight weeks of androgen priming by daily low-dose hCG injections before ICSI treatment in women with low ovarian reserve.

Does 8 weeks of continuous low-dose hCG administration increase the proportion of antral follicles that reach the preovulatory state during ovarian stimulation (OS) in women with low ovarian reserve? The proportion of antral follicles (2-10 mm) that reached the preovulatory state did not increase. The administration of androgens prior to OS might upregulate FSH receptor (FSHR) expression on granulosa cells, making follicles more responsive to exogenous FSH stimulation during OS. LH and hCG stimulate the local follicular androgen synthesis in theca cells and may be used as an endogenous androgen priming method. Exogenous priming by testosterone and dehydroepiandrosterone (DHEA) have been shown to increase the number of retrieved oocytes and live birth rate but the studies are small, and their use is associated with side effects. A prospective, paired, non-blinded single-center study including 20 women serving as their own controls conducted between January 2021 and July 2021 at The University Hospital Copenhagen Rigshospitalet, Denmark. Participants underwent two identical consecutive IVF/ICSI treatments, a Control cycle and a Study cycle, separated by ∼8 weeks (two menstrual cycles) of daily injections of 260 IU recombinant hCG (rhCG). A freeze-all strategy was applied in the Control cycle. Both IVF/ICSI cycles were performed in a fixed GnRH antagonist protocol using a daily dose of 300 IU recombinant FSH (rFSH) and GnRH antagonist 0.25 mg from stimulation days 5-6. Follicular output rate, defined as the number of follicles >16 mm on hCG trigger day divided by the antral follicle count (2-10 mm) at baseline, did not increase after 8 weeks of hCG priming (P = 0.8). The mean number of oocytes retrieved was significantly higher after the hCG priming being 4.7 (2.8) vs 3.2 (1.7) in the Study and Control cycle, respectively (P = 0.01). The duration of stimulation was longer in the Study versus the Control cycle (P = 0.05), despite the use of identical hCG trigger criterion and similar diameters of the three biggest follicles on hCG trigger day in the two cycles (P = 0.9). The sample size was small, and the number of oocytes retrieved was not the primary endpoint. Larger studies are needed to confirm this finding. Long-term, low-dose rhCG administration may increase the number of oocytes retrieved during IVF/ICSI in women with low ovarian reserve, but more research is needed before firm conclusions can be drawn. This study was funded by an unrestricted grant from Gedeon Richter. A.P. reports personal consulting fees from PregLem SA, Novo Nordisk A/S, Ferring Pharmaceuticals A/S, Gedeon Richter Nordics AB, Cryos International, and Merck A/S outside the submitted work and payment or honoraria for lectures from Gedeon Richter Nordics AB, Ferring Pharmaceuticals A/S, Merck A/S, and Theramex and Organon & Co. Grants to the institution have been provided by Gedeon Richter Nordics AB, Ferring Pharmaceuticals A/S, and Merck A/S and receipt of equipment by the institution from Gedeon Richter Nordics AB is reported. The remaining authors have no conflicts of interest to declare. ClinicalTrials.gov Identifier: NCT04643925.

Human Chorionic Gonadotropin in the Regulation of T-Helpers Type 17

Chorionic gonadotropin (hCG) is a key pregnancy hormone that regulates steroidogenesis and has immunomodulatory activity. We studied the effects of native and recombinant hCG on the differentiation, proliferation, and production of IL-17 and IFN-ɣ by T-helper cells induced into the phenotype of T-helper type 17 (Th17) in vitro. We found that hCG had no significant effects on the level of Th17 cells, as assessed by RORɣτ expression, and the proliferation of these cells (Ki-67+). In addition, no effects of hCG on the production of IL-17 and IFN-ɣ by T-helpers induced in the Th17 phenotype were found. At the same time, recombinant hCG (100 IU/mL) increased the number of non-Th17 T-helpers (RORγt-Ki-67+). Thus, hCG did not modulate Th17 cells in our experimental model.

Frozen-thawed embryo transfer: does the addition of low-dose choriogonadotropin alfa to progesterone in the luteal phase of artificial cycles improve the endometrium and increase the chances of pregnancy?

Primary: To evaluate the effect of low doses of recombinant hCG (choriogonadotropin alfa) in the luteal phase of frozen-thawed embryo transfers (FET) of artificial cycles on the chances of pregnancy in patients aged ≤38years. Secondary: To assess the chances of pregnancy in the FET groups of artificial cycles using micronized vaginal progesterone (VP) versus injectable intramuscular progesterone (IMP) and the chances of pregnancy in type-1 embryo transfers (two top embryos). This retrospective cohort study included 122 cycles of FET and compared two groups of patients aged 38 years or younger, one given hCG in the luteal phase and one not administered hCG. The clinical pregnancy rates (CPR) in the control and hCG groups were 45% and 45.16%, respectively (p=0.9999). The live birth rates (LBR) were 33.33% and 32.25%, respectively, (p=0.99909). The CPR in the VP group (83 patients) was 46.89% versus 41.02% in the IMP group, (p=0.5459). The LBR was 33.73% in the VP group and 30.76% in the IMP group (39 patients), (p=0.7559). The CPR and LBR of patients undergoing FET in groups prescribed and not prescribed low doses of recombinant hCG were similar. No significant difference was found between patients given VP or IMP.