Is it necessary to monitor the serum luteinizing hormone (LH) concentration on the human chorionic gonadotropin (HCG) day among young women during the follicular-phase long protocol? A retrospective cohort study.

BACKGROUND: The normal physiological function of LH requires a certain concentration range, but because of pituitary desensitization, even on the day of HCG, endogenous levels of LH are low in the follicular-phase long protocol. Therefore, our study aimed to determine whether it is necessary to monitor serum LH concentrations on the day of HCG (LHHCG) and to determine whether there is an optimal LHHCG range to achieve the desired clinical outcome. METHODS: A retrospective cohort study included 4502 cycles of in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) from January 1, 2016, to June 30, 2019, in a single department. The main outcome measures included retrieved eggs, available embryos, and live birth rate. RESULTS: The LHHCG was divided into five groups: Group A (LH ≤ 0.5), Group B (0.5 IU/L < LH ≤ 1.2 IU/L), Group C (1.2 IU/L < LH ≤ 2.0 IU/L), Group D (2.0 IU/L < LH ≤ 5.0 IU/L), Group E (LH > 5 IU/L). In terms of the numbers of retrieved eggs (15.22 ± 5.66 vs. 13.54 ± 5.23 vs. 12.90 ± 5.05 vs. 12.30 ± 4.88 vs. 9.6 ± 4.09), diploid fertilized oocytes (9.85 ± 4.70 vs. 8.69 ± 4.41 vs. 8.39 ± 4.33 vs. 7.78 ± 3.96 vs. 5.92 ± 2.78), embryos (7.90 ± 4.48 vs. 6.83 ± 4.03 vs. 6.44 ± 3.88 vs. 6.22 ± 3.62 vs. 4.40 ± 2.55), and high-quality embryos (4.32 ± 3.71 vs. 3.97 ± 3.42 vs. 3.76 ± 3.19 vs. 3.71 ± 3.04 vs. 2.52 ± 2.27), an increase in the LHHCG level showed a trend of a gradual decrease. However, there was no significant difference in clinical outcomes among the groups (66.67% vs. 64.33% vs. 63.21% vs. 64.48% vs. 63.33%). By adjusting for confounding factors, with an increase in LHHCG, the number of retrieved eggs decreased (OR: -0.351 95%CI - 0.453-[- 0.249]). CONCLUSION: In the follicular-phase long protocol among young women, monitoring LHHCG is recommended in the clinical guidelines to obtain the ideal number of eggs.

A Randomized Controlled Trial on the Efficacy and Safety of Low-Dose hCG in a Short Protocol with GnRH Agonist and Ovarian Stimulation with Recombinant FSH (rFSH) During the Follicular Phase in Infertile Women Undergoing ART.

Τhis study aims to investigate whether the addition of low-dose hCG throughout stimulation in infertile women undergoing IVF improves IVF outcome parameters. This is a prospective, multicenter, randomized, double-blind, placebo-controlled, Phase IIIb clinical study, conducted in three university IVF units. We studied whether the addition of 100 IU hCG/day to a short GnRH agonist IVF protocol from the onset of the follicular phase (group 1, n=40) or placebo (group 2, n=41) had any impact on the number of high-quality transferred embryos at day 2 and clinical pregnancy rates. The comparison encompassed descriptive statistics, and univariate and multivariate analyses. Concerning the primary outcomes, we found no differences in both the number of high-quality embryos (≥2) at day 3 [21/40 (52.5%) vs. 14/41 (34.2%), p=0.095] and clinical pregnancy rates [10/40 (25%) vs. 10/41 (24.4%), p=0.949], respectively. Similarly, there were no differences concerning the secondary outcomes preset for this trial. According to the results of the multivariate logistic regression analysis, no significant associations were noted for primary outcomes (clinical pregnancy: adjusted OR=0.89, 95% CI: 0.29-2.75; (≥2 excellent quality embryos at day 3: adjusted OR=0.54, 95% CI: 0.21-1.42, with group 1 set as reference category); similarly, no differences were noted with respect to secondary outcomes, except from the increased odds of ≥2 poor-quality embryos at day 3 occurring in group 2 (adjusted OR= 11.69, 95%CI: 1.29-106.19). The addition of low-dose hCG to a short GnRH agonist protocol for IVF does not improve the number of top-quality embryos and clinical pregnancy rates.

Influence of conceptus presence and preovulatory estradiol exposure on uterine gene transcripts and proteins around maternal recognition of pregnancy in beef cattle.

The uterine environment must provide sufficient endocrine conditions and nutrients for pregnancy maintenance and conceptus survival. The objective of this study was to determine the effects of preovulatory estradiol and conceptus presence on uterine transcripts and uterine luminal fluid (ULF) proteins. Beef cows/heifers were synchronized and artificially inseminated (d 0). Uteri were flushed (d 16); conceptuses and endometrial biopsies were collected. Total cellular RNA was extracted from endometrium for RNA sequencing and RT-PCR validation. There were two independent ULF pools made for each of the following groups: highE2/conceptus, highE2/noconceptus, lowE2/conceptus, and lowE2/noconceptus that were analyzed using the 2D LC-MS/MS based iTRAQ method. There were 64 differentially expressed genes (DEGs) and 77 differentially expressed proteins (DEPs) in common among the highE2/conceptus vs highE2/noconceptus and lowE2/conceptus vs lowE2/noconceptus groups. In summary, the interaction between preovulatory estradiol and the conceptus induces the expression of genes, proteins, and pathways necessary for pregnancy.

Early Follicular Phase Human Chorionic Gonadotropin Addition May Improve the Outcomes of In Vitro Fertilization/Intracytoplasmic Sperm Injection in Patients With "Unpredictable" Poor Response to Gonadotropin-Releasing Hormone Antagonist Protocol.

Purpose: To compare the effects of early and mid-late follicular phase administration of 150 IU of human chorionic gonadotropin (hCG) on gonadotropin-releasing hormone (GnRH) antagonist protocol in "unpredictable" poor ovarian response (POR) women undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment. Methods: A retrospective single-center cohort study was conducted on 67 patients with "unpredictable" POR in their first IVF/ICSI cycle receiving GnRH antagonist protocol. Patients were treated with a second IVF/ICSI cycle using the same GnRH antagonist protocol with the same starting dose of recombinant follicle-stimulating hormone (rFSH) as the first cycle; a daily dose of 150 IU of hCG was administrated on either stimulation day 1 (Group A, n = 35) or day 6 (Group B, n = 32). The number of oocytes retrieved, number of usable embryos, serum level of estradiol (E2) on day of hCG trigger, and clinical pregnant outcomes were studied. Results: The addition of 150 IU of hCG on either the first day or sixth day of stimulation increases the serum level of E2, luteinizing hormone (LH), and hCG on the day of hCG trigger. Only the use of 150 IU of hCG on the first stimulation day improved the number of oocytes retrieved, mature of oocytes, and usable embryos, but not the addition of hCG on stimulation day 6. Implantation rate, clinical pregnancy rate, and ongoing pregnancy rate showed an increasing trend in patients receiving 150 IU of hCG in the early phase compared with mid-late phase, even thought there was no statistically significant difference. Conclusions: Our study demonstrated that adding 150 IU of hCG in subsequent GnRH antagonist cycle in "unpredictable" poor responders is associated with the improvement of response to stimulation. Furthermore, early follicular phase addition of 150 IU of hCG significantly increased the number of oocytes retrieved and usable embryos than did the mid-late addition of the same dose.

Double daily doses of cetrorelix may raise follicular phase progesterone more compared to single doses in poor ovarian response patients.

PURPOSE: There is evidence that follicular phase progesterone rise [FPPR] adversely affects fresh in vitro fertilization [IVF] cycles. A single daily dose of cetrorelix has been used to prevent early luteinizing Hormone (LH) surge. We speculated that doubling the daily dose might have a positive effect in patients who have early LH surges despite receiving the single daily dose treatment. However, a double daily dose of cetrorelix seems to cause FPPR in poor ovarian response (POR) patients. MATERIALS AND METHODS: On human chorionic gonadotropin [hCG] injection days, the progesterone levels of POR patients who received a single daily dose of cetrorelix (group 1, n = 59) were compared with progesterone levels of the patients who received a double daily dose of cetrorelix (group 2, n = 75). The two groups had statistically similar demographic data. The patients who had FPPR were detected, and a comparison of progesterone levels, using 0.8, 1.0, and 1.2 [ng/mL] of progesterone as cut-off levels, was made between patients of both groups. RESULTS: FPPR patients in group 2 had significantly higher progesterone levels during hCG day, contrary to expectations. When progesterone cut-off levels of 0.8, 1.0, and 1.2 [ng/mL] were used for group 1 patients, 15.3%, 13.6%, and 6.8% of the patients developed FPPR, respectively When the progesterone cut-off levels of 0.8, 1.0, and 1.2 [ng/mL] were used for group 2, the results detected were 45.3%, 30.7%, and 21.3%, respectively. A significant statistical difference in progesterone levels was observed between the groups. CONCLUSION: While the double daily dose of cetrorelix was initially thought to more effectively suppress early LH rise by some authors, we have seen that it increases the FPPR more when compared to a single daily dose regime. We suggest using frozen cycles instead of fresh cycles in order to have better endometrial receptivity in patients who seem to benefit from higher daily doses of cetrorelix.

Luteal Phase Ovarian Stimulation versus Follicular Phase Ovarian Stimulation results in different Human Cumulus cell genes expression: A pilot study.

Background: Luteal-phase ovarian stimulation (LPOS) is an alternative in vitro fertilization (IVF) protocol. However, limited data showed the genes expression of cumulus cells (CCs) in LPOS. Therefore, this study aimed to investigate CC genes expression between LPOS and follicular-phase ovarian stimulation (FPOS) in poor ovarian responders (PORs) undergoing IVF cycles. Methods: This was a prospective non-randomized trial (ClinicalTrials.gov Identifier: NCT03238833). A total of 36 PORs who met the Bologna criteria and underwent IVF cycles were enrolled. Fifteen PORs were allocated to the LPOS group, and 21 PORs were allocated to the FPOS group. The levels of CC genes involved in inflammation (CXCL1, CXCL3, TNF, PTGES), oxidative phosphorylation (NDUFB7, NDUFA4L2, SLC25A27), apoptosis (DAPK3, BCL6B) and metabolism (PCK1, LDHC) were analyzed using real-time quantitative PCR and compared between the two groups. Results: The number of retrieved oocytes, metaphase II oocytes, fertilized oocytes, day-3 embryos and top-quality day-3 embryos, clinical pregnancy rates and live birth rates were similar between the two groups except for significantly high progesterone levels in the LPOS group. The mRNA expression levels of CXCL1 (0.51 vs 1.00, p < 0.001) and PTGES (0.30 vs 1.00, p < 0.01) were significantly lower in the LPOS group than in the FPOS group. The LPOS group had significantly lower mRNA expression of NDUFB7 (0.12 vs 1.00, p < 0.001) and NDUFA4L2 (0.33 vs 1.00, p < 0.01) than the FPOS group. DAPK3 (3.81 vs 1.00, p < 0.05) and BCL6B (2.59 vs 1.00, p < 0.01) mRNA expression was significantly higher in the LPOS group than in the FPOS group. Increased expression of PCK1 (3.13 vs. 1.00, p < 0.001) and decreased expression of LDHC (0.12 vs. 1.00, p < 0.001) were observed in the LPOS group compared to the FPOS group. Conclusions: Our data revealed different CC genes expression involving in inflammation, oxidative phosphorylation, apoptosis and metabolism between LPOS and FPOS in PORs. However, the results are non-conclusive; further large-scale randomized controlled trials are needed to validate the results.

DuoStim cycles potentially boost reproductive outcomes in poor prognosis patients.

AIM: To evaluate the overall performance and oocyte quality of follicular phase stimulation (FPS) vs. luteal phase stimulation (LPS) among patients undergoing double ovarian stimulation (DuoStim). MATERIALS AND METHODS: Observational retrospective two-center cohort study including 79 infertile women who underwent a total of 87 DuoStim cycles between January 2017 and May 2019. Besides assessing baseline characteristics in order to determine the patients' clinical profile, we analyzed the FPS and LPS regarding the total dose of gonadotropin received, the duration of stimulation, the number and maturity of oocytes, fertilization and blastocyst formation rates, and the number of blastocysts obtained. RESULTS: The patients' baseline characteristics were compatible with a diminished ovarian reserve and poor reproductive prognosis. While the luteal phase needed longer stimulation (12 days (5-19) vs. 11 (7-16), p < .001) and slightly higher gonadotropin doses (2946 ± 890 IU vs. 2550 ± 970 IU, p < .001), no significant differences were detected in the oocyte maturity, fertilization, and blastocyst formation rates. However, the number of oocytes retrieved (5 (0-16) vs. 4 (0-15), p = .006), mature oocytes (4 (0-15) vs. 3 (0-11), p = .032), and blastocysts obtained (70 vs. 53) were substantially greater after LPS. CONCLUSIONS: The DuoStim strategy in poor prognosis patients increases the number of oocytes and blastocysts available. Moreover, the number of oocytes and blastocysts obtained are higher after LPS when compared to FPS. Thus, it should be considered for selected patients in order to not only improve reproductive outcomes but also shorten the time to pregnancy.

The best execution of the DuoStim strategy (double stimulation in the follicular and luteal phase of the same ovarian cycle) in patients who are poor ovarian responders.

BACKGROUND: Patients found to be poor ovarian responders (POR) are a challenging patient population for any assisted reproduction technology. Despite attempts at various controlled ovarian stimulation schemes, reproductive outcomes in this patient population have not improved. In recent years, the DuoStim protocol (both follicular and luteal phase stimulation during the same menstrual cycle) has shown a potential for use in patients with POR. METHODS: This retrospective study reviewed the medical records of 304 women who were diagnosed as POR and underwent the DuoStim protocol. We compared follicular phase stimulation (FPS) data and luteal phase stimulation (LPS) data of the same patients. We also compared the effects of different trigger drugs including urine human chorionic gonadotropin (uHCG; 10,000 IU), recombinant human chorionic gonadotropin (rHCG; 250 µg), and gonadotropin-releasing hormone agonist (GnRH-a; 0.2 mg) at the FPS and LPS stages. RESULTS: POR undergoing the DuoStim protocol resulted in a significantly higher number of oocytes retrieved, normal fertilised oocytes, cleaved embryos, cryopreserved embryos, and good quality embryos at the LPS stage than at the FPS stage. Trigger drugs at the FPS stage did not affect the FPS stage data. Regardless of the stage, rHCG and GnRH-a yielded significantly more cryopreserved embryos and good quality embryos than uHCG. CONCLUSION: The use of GnRH-a or rHCG as the trigger drug may be better than uHCG in both the FPS and LPS stages for POR undergoing the DuoStim protocol. This will increase the number of good quality embryos at the LPS stage. We found that the LPS stage results in more oocytes (and therefore more embryos) than the FPS stage.

Effect of Central Injection of Neostigmine on the Bacterial Endotoxin Induced Suppression of GnRH/LH Secretion in Ewes during the Follicular Phase of the Estrous Cycle.

Induced by a bacterial infection, an immune/inflammatory challenge is a potent negative regulator of the reproduction process in females. The reduction of the synthesis of pro-inflammatory cytokine is considered as an effective strategy in the treatment of inflammatory induced neuroendocrine disorders. Therefore, the effect of direct administration of acetylcholinesterase inhibitor-neostigmine-into the third ventricle of the brain on the gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretions under basal and immune stress conditions was evaluated in this study. In the study, 24 adult, 2-years-old Blackhead ewes during the follicular phase of their estrous cycle were used. Immune stress was induced by the intravenous injection of LPS Escherichia coli in a dose of 400 ng/kg. Animals received an intracerebroventricular injection of neostigmine (1 mg/animal) 0.5 h before LPS/saline treatment. It was shown that central administration of neostigmine might prevent the inflammatory-dependent decrease of GnRH/LH secretion in ewes and it had a stimulatory effect on LH release. This central action of neostigmine is connected with its inhibitory action on local pro-inflammatory cytokines, such as interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)α synthesis in the hypothalamus, which indicates the importance of this mediator in the inhibition of GnRH secretion during acute inflammation.

The efficacy of a newly developed neurokinin 3 receptor agonist B21-750 on luteinizing hormone secretion in cycling goats.

This study aimed to investigate the efficacy of a newly developed NK3 receptor agonist (B21-750) on the secretion of luteinizing hormone (LH) in association with ovarian steroid hormones during the follicular phase (FP, n = 5) and luteal phase (LP, n = 5) of Shiba goats. The FP group was treated with both prostaglandin F2α and progesterone-controlled internal drug release (CIDR) inserts for 10 d, and B21-750 (200 nmol) was injected 12 h after removing the CIDR. Meanwhile, the LP group received B21-750 injections on a day during the mid-luteal phase. LH secretion increased at 1 h after B21-750 injection in both groups. The percent changes in the area under the curve of LH was higher during the hour after injection than during the hour before injection in both groups. Thus, this study demonstrated that B21-750 induces rapid LH secretion for a short period during both the follicular and luteal phases.

The effect of a GnRH antagonist on follicle maturation in normal women.

RESEARCH QUESTION: Ganirelix is a gonadotrophin-releasing hormone (GnRH) antagonist used for the prevention of premature LH surge during ovarian stimulation. What is the impact of ganirelix on follicle maturation in normal women? DESIGN: Ten normally cycling women were investigated during two menstrual cycles, i.e. cycle 1 (control) and cycle 2 (ganirelix). During both cycles, daily blood samples were taken from day 2, while transvaginal ultrasound scans were performed on cycle days 8 and 10 and daily thereafter. During cycle 2, all women were given 0.25 mg/day subcutaneous injections of the GnRH antagonist ganirelix from day 2 until the day of the endogenous LH surge onset in cycle 1. RESULTS: During treatment with ganirelix, serum FSH and oestradiol concentrations remained stable, while those of LH decreased significantly on days 3, 4, 7 and 9 (P < 0.05) compared with controls. Nevertheless, there was no significant within-cycle variation in LH concentrations. From day 10 onwards, no follicle maturation was observed in cycle 2, in contrast to cycle 1. Ovulation occurred in 9 of 10 women in cycle 1. In cycle 2, ovulation was delayed by at least 1 week in eight women. Follicle growth and ovulation occurred in only one woman while on ganirelix treatment. CONCLUSIONS: This study demonstrates for the first time that in normal women dominant follicle selection failed during treatment with ganirelix. As there was a similar gonadotrophin profile in the two cycles, it is suggested that ganirelix interferes with the process of follicle selection by acting in the ovary.

Response to ovulation trigger is correlated to late follicular phase progesterone levels: A hypothesis explaining reduced reproductive outcomes caused by increased late follicular progesterone rise.

STUDY QUESTION: Is there an association between progesterone (P4) levels on the day of hCG or GnRH trigger and on the day of oocyte retrieval in IVF/ICSI cycles? SUMMARY ANSWER: A significant positive correlation between P4 levels on the day of trigger and the day of oocyte retrieval is seen; HCG trigger induces a steeper P4 increase than GnRHa trigger. WHAT IS KNOWN ALREADY: FSH induces LH receptor (LHR) expression on granulosa cells, and LHR produces progesterone when exposed to LH-like activity. FSH per se also to some extent induces P4 secretion. Late follicular phase progesterone rise has been associated with reduced reproductive outcomes. STUDY DESIGN, SIZE, DURATION: This study is based on data from a previously published RCT conducted from 2009 to 2011. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 384 participants were enrolled; 199 received 5000 IU hCG and 185 received buserelin 0.5 mg for triggering ovulation. P4 was measured on the day of ovulation induction and on the day of oocyte retrieval. FSH consumption and number of retrieved follicles were recorded. MAIN RESULTS AND THE ROLE OF CHANCE: A significant linear relationship between P4 on the day of ovulation induction and oocyte retrieval was seen in the hCG trigger group (P < 0.00001) as well as in the GnRHa trigger group (P < 0.00001). The P4 ratio (the increase in P4 between ovulation induction and oocyte retrieval) was significantly higher in the group of patients with <5 follicles compared to those with 5-15 and >15 follicles (P < 0.0001). The FSH consumption per follicle was significantly higher in the group of patients with <5 follicles compared to those with 5-15 and >15 follicles (P < 0.0001). LIMITATIONS, REASONS FOR CAUTION: Although the study demonstrates a significant correlation between P4 levels before and after ovulation trigger, it does not demonstrate a causal relation to the number of LHRs present on granulosa cells. WIDER IMPLICATIONS OF THE FINDINGS: The findings of this study support the proposed hypothesis that follicles exposed to high levels of FSH during ovarian stimulation will respond with an inappropriately high LHR expression. This in turn causes a high P4 output in response to the trigger. This study further expands our understanding of the underlying mechanisms affecting reproductive outcomes in relation to ovarian stimulation. STUDY FUNDING/COMPETING INTEREST(S): The authors received no specific funding for this work and disclose no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

Proteomic changes in uterine flushings after levonorgestrel treatment and effects on sperm function.

When levonorgestrel (LNG) is given for emergency contraception during the follicular phase, it not only inhibits or delays ovulation, but also induces changes in endometrial secretions that modulate sperm functionality. In order to characterize the female reproductive tract secreted molecules that may affect human spermatozoa, we analyzed changes in the protein content of uterine flushings obtained from women during the periovulatory phase of a control and a LNG-treated menstrual cycle. Lectin affinity analysis and 2D gel electrophoresis of uterine samples showed changes in protein glycosylation patterns and the presence of 31 differentially expressed proteins (8 upregulated and 23 downregulated). Mass spectrometry and Western blot analyses of the differential expressed proteins showed lactotransferrin (LTF) as one of the upregulated molecules by LNG. In this study, LTF exhibited significant dose-related effects on sperm functionality, particularly a decrease of calcium ionophore-induced acrosome reaction and protein tyrosine phosphorylation. Overall, the results indicated that LNG promoted changes in the proteome of uterine secretions that might compromise human sperm capacitation. These data further support the participation of other mechanisms of action of LNG as emergency contraceptive, in addition to those on ovulation.

Effect of low-dose dexamethasone on patients with elevated early follicular phase progesterone level and pregnancy outcomes in IVF-ET treatment: A randomized controlled clinical trial.

OBJECTIVE: To evaluate the effect of low-dose dexamethasone on patients with elevated early follicular progesterone levels in IVF-ET treatment. DESIGN: Randomized controlled trial. SETTING: In vitro fertilization (IVF) centre. PATIENT(S): A total of 459 patients undergoing a first IVF/ICSI cycle. INTERVENTION(S): If progesterone concentration exceeded 1.9 nmol/L on days 3-4 of ovarian stimulation, the patients in dexamethasone (DEX) group were treated with oral dexamethasone 0.75 mg/d, and the patients in control group received no extra treatment. MAIN OUTCOME MEASURE: The cumulative live-birth rate (per cycle started) in 2 years. RESULTS: The total dose of gonadotropins (1987 ± 536 IU in DEX group vs 2135 ± 701 IU in control group, P = 0.009) and the serum concentrations of progesterone on human chorionic gonadotropin (HCG) day (3.1 ± 1.4 nmol/L in DEX group vs 4.0 ± 1.3 nmol/L in control group, P < 0.001) were both significantly lower in DEX group than that in control. No significant differences between the two groups were observed in the number of oocytes, two pronuclear (2PN) embryos and clinical pregnancy rate. In addition, the cumulative live-birth rate was significantly higher in the DEX group than that in controls (70.0% vs 61.1%, P = 0.029, 95% confidence interval: 1.01-2.19). CONCLUSION(S): Progesterone secretion can be suppressed by dexamethasone, and dexamethasone may sensitize the ovary to gonadotropin stimulation in IVF treatment. In addition, the cumulative live-birth rate was significantly higher in the DEX group than in controls, and the obstetric and neonatal outcomes support the safety of DEX treatment in IVF.

Luteal phase anovulatory follicles result in the production of competent oocytes: intra-patient paired case-control study comparing follicular versus luteal phase stimulations in the same ovarian cycle.

STUDY QUESTION: Are the mean numbers of blastocysts obtained from sibling cohorts of oocytes recruited after follicular phase and luteal phase stimulations (FPS and LPS) in the same ovarian cycle similar? SUMMARY ANSWER: The cohorts of oocytes obtained after LPS are larger than their paired-FPS-derived cohorts and show a comparable competence, thus resulting in a larger mean number of blastocysts. WHAT IS KNOWN ALREADY: Three theories of follicle recruitment have been postulated to date: (i) the 'continuous recruitment' theory, (ii) the 'single recruitment episode' theory and (iii) the 'wave' theory. Yet, a clear characterization of this crucial biological process for human reproduction is missing. Recent advances implemented in in vitro fertilization (IVF), such as blastocyst culture, aneuploidy testing and vitrification, have encouraged clinicians to maximize the exploitation of the ovarian reserve through tailored stimulation protocols, which is crucial especially for poor prognosis patients aiming to conceive after IVF. LPS has been already successfully adopted to treat poor prognosis or oncological patients through Duostim, LPS-only or random-start ovarian stimulation approaches. Nevertheless, little, and mainly retrospective, evidence has been produced to support the safety of LPS in general. Feasibility of the LPS approach would severely question the classic 'single recruitment episode' theory of follicular development. STUDY DESIGN, SIZE, DURATION: This case-control study was conducted with paired follicular phase- and luteal phase-derived cohorts of oocytes collected after stimulations in the same ovarian cycle (DuoStim) at two private IVF clinics between October 2015 and December 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study included 188 poor prognosis patients undergoing DuoStim with preimplantation genetic testing for aneuploidies (PGT-A). FPS and LPS were performed with the same daily dose of recombinant-gonadotrophins in an antagonist protocol. Blastocyst culture, trophectoderm biopsy, vitrification and frozen-warmed euploid single blastocyst transfers were performed. The primary outcome was the mean number of blastocysts obtained per oocyte retrieval from paired-FPS- and LPS-derived cohorts (required sample size = 165 patients; power = 90%). Mean blastulation and euploidy rates were monitored, along with the number of oocytes, euploid blastocysts and clinical outcomes. MAIN RESULTS AND THE ROLE OF CHANCE: Significantly fewer blastocysts were obtained after FPS than LPS (1.2 ± 1.1 vs. 1.6 ± 1.6, P < 0.01), due to fewer oocytes collected (3.6 ± 2.1 vs. 4.3 ± 2.8, P < 0.01) and a similar mean blastocyst rates per retrieval (33.1% ± 30.3% vs. 37.4% ± 30.8%, P = NS). The number of oocytes collected were correlated (R = 0.5, P < 0.01), while the blastocyst rates were uncorrelated among paired-FPS- and LPS-derived cohorts. Overall, a significantly lower chance of producing blastocyst(s) was reported after FPS than after LPS: 67.6% (n = 127/188, 95%CI: 60.3-74.1) vs. 77.1% (n = 145/188, 95%CI: 70.3-82.8; P = 0.05). The mean euploidy rates per retrieval were similar between FPS- and LPS-derived cohorts of oocytes (13.6% ± 22.8% vs. 16.3% ± 23.4%, P = NS). Therefore, on average fewer euploid blastocysts (0.5 ± 0.8 vs. 0.7 ± 1.0, P = 0.02) resulted from FPS. Similar ongoing-pregnancy/delivery rates were reported, to date, after FPS- and LPS-derived euploid single blastocyst transfers: 42.4% (n = 28/66, 95%CI: 30.5-55.2) vs. 53.8% (n = 35/65, 95%CI: 41.1-66.1; P = NS). LIMITATIONS, REASONS FOR CAUTION: More studies need to be conducted in the future to confirm the safety of LPS, especially in terms of ovarian and follicular environment, as well as the clinical, peri-natal and post-natal outcomes. Here, we showed preliminary data suggesting a similar ongoing implantation/delivery rate (>22 weeks) between FPS- and LPS-derived euploid blastocysts, that need to be extended in the future, to populations other than poor prognosis patients and using approaches other than DuoStim together with a constant monitoring of the related peri-natal and post-natal outcomes. WIDER IMPLICATIONS OF THE FINDINGS: These data, from a paired study design, highlight that LPS-derived oocytes are as competent as FPS-derived oocytes, thereby adding some evidence to support the use of LPS for poor prognosis and oncological patients and to question the 'single recruitment episode' theory of follicle recruitment. These findings also encourage additional studies of the basics of folliculogenesis, with direct clinical implications for the management of ovarian stimulation in IVF. TRIAL REGISTRATION: None. STUDY FUNDING/COMPETING INTEREST(S): No external funds were used for this study and there are no conflicts of interest.

Progesterone administration does not acutely alter LH pulse secretion in the mid-follicular phase in women.

It remains unclear how rapidly progesterone suppresses luteinizing hormone (LH) pulse frequency in women. Previous studies suggested that progesterone markedly increases LH pulse amplitude but does not slow LH pulse frequency within 10 h in estradiol-pretreated women studied during the late follicular phase. However, this experimental paradigm may be a model of preovulatory physiology, and progesterone may have different effects at other times of the cycle. We studied regularly cycling, nonobese women without hyperandrogenism to assess the acute effect of progesterone during the midfollicular phase and in the absence of estradiol pretreatment. The study involved two admissions in separate cycles (cycle days 5-9). For each admission, either oral micronized progesterone (100 mg) or placebo was administered at 0900 h in a randomized, double-blind fashion. Frequent blood sampling was performed between 0900 and 1900 h to define 10-h LH pulsatility. Treatment crossover (placebo exchanged for progesterone and vice versa) occurred in a subsequent cycle. After an interim futility analysis, the study was halted after 7 women completed study. Mean progesterone concentrations after placebo and progesterone administration were 0.5 ± 0.1 (mean ± SD) and 6.7 ± 1.6 ng/mL, respectively. Compared to placebo, progesterone was not associated with a significant difference in 10-h LH pulse frequency (0.79 ± 0.35 vs. 0.77 ± 0.28 pulses/h, P = 1.0) or amplitude (3.6 ± 2.8 vs. 4.3 ± 2.8 IU/L, P = 0.30). This study suggests that LH pulse frequency is not rapidly influenced by progesterone administration during the midfollicular phase.

Neuroestradiol in regulation of GnRH release.

Contribution to Special Issue on Fast effects of steroids. The concept that the positive feedback effect of ovarian estradiol (E2) results in GnRH and gonadotropin surges is a well-established principle. However, a series of studies investigating the rapid action of E2 in female rhesus monkeys has led to a new concept that neuroestradiol, synthesized and released in the hypothalamus, also contributes to regulation of the preovulatory GnRH surge. This unexpected finding started from our surprising observation that E2 induces rapid stimulatory action in GnRH neurons in vitro. Subsequently, we confirmed that a similar rapid stimulatory action of E2 occurs in vivo. Unlike subcutaneous injection of E2 benzoate (EB), a brief (10-20 min), direct infusion of EB into the median eminence in ovariectomized (OVX) female monkeys rapidly stimulates release of GnRH and E2 in a pulsatile manner, and the EB-induced GnRH and E2 release is blocked by simultaneous infusion of the aromatase inhibitor, letrozole. This suggests that stimulated release of E2 is of hypothalamic origin. To further determine the role of neuroestradiol we examined the effects of letrozole on EB-induced GnRH and LH surges in OVX females. Results indicate that letrozole treatment greatly attenuated the EB-induced GnRH and LH surges. Collectively, neuroestradiol released from the hypothalamus appears to be necessary for the positive feedback effect of E2 on the GnRH/LH surge.

Premature progesterone elevation: targets and rescue strategies.

Progesterone elevation during the late follicular phase of ovarian stimulation for in vitro fertilization negatively impacts the assisted reproductive technology-outcome. The evidence available supports an advanced endometrial maturation and a direct negative effect on its receptivity. On the other hand, some retrospective analysis suggests an impairment of oocyte and embryo quality. Recent publications confirm that enhanced follicle-stimulating hormone-stimulation towards the end of the follicular phase of ovarian stimulation is the main course of progesterone elevation. A key element in preventing this event is the individualization of ovarian stimulation according to the patient's ovarian reserve and the adaption of the stimulation dosage during late follicular phase according to the patient's response. Additional measures as corticosteroid administration, avoidance of prolonged stimulation and cycle segmentation with freeze-all-policy can be discussed.

Luteinizing Hormone Facilitates Antral Follicular Maturation and Survival via Thecal Paracrine Signaling in Cattle.

LH supplementation in assisted reproductive technology cycles improves the ongoing pregnancy rate in women with poor ovarian response (POR). However, our knowledge of the precise role of LH during the follicular phase of the menstrual cycle is incomplete. To explore the role of LH in the maturation of small antral follicles, we used an in vitro two-cell system that involved coculturing bovine granulosa cells (GCs) and theca cells (TCs) on a collagen membrane. Treatment of TCs with LH stimulated androgen production in TCs by inducing the expression of androgenic factors, subsequently increasing estrogen biosynthesis in GCs by providing androgen substrates, and inducing aromatase expression. LH stimulation of TCs induced functional LH receptor expression in GCs, a response modulated by the synthesis and action of estrogen. In the presence of TCs, LH stimulation of TCs and FSH stimulation of GCs increased the expression of IGF-1, IGF-2, and IGF-1 receptor in GCs. LH-induced expression of thecal IGF-1 protected GCs from apoptosis and promoted GC survival. Furthermore, LH stimulation of TCs increased FSH sensitivity in GCs. Thus, the LH-TC axis may be involved in the acquisition of LH dependence and the survival of small antral follicles by upregulating androgen/estrogen biosynthesis and activating the IGF system. The use of LH supplementation in ovarian stimulation may increase gonadotropin sensitivity in small antral follicles and promote follicular growth and survival by suppressing GC apoptosis and follicular atresia, resulting in multiple follicular development, even in patients with POR.

The Effect of Steroid Hormones on Ovarian Follicle Development.

Ovarian follicular cell undergoes extensive proliferation and differentiation during the period that the follicle evolved from the primordial state to its ovulatory phase and then corpus luteum status. During this process, different and various levels of steroid hormones in follicular fluid, or obtained from circulation and adjacent cells as granulosa and theca cells, or from environment and diet will all affect the process of follicular growth and development. Differential steroid hormones might have differential effects on ovarian folliculogenesis via the effect on granulosa cell growth and follicular fluid formation that involves cell proliferation, apoptosis, and angiogenesis within the follicle. In this chapter we further discuss the role of various steroid hormones such as estrogens, progesterone, and androgens on ovarian follicular growth and development. Various stages of follicle development that might be disturbed by the steroid hormones are also discussed in this chapter.