No association between endogenous LH and pregnancy in a GnRH antagonist protocol: part I, corifollitropin alfa

The relationship between endogenous LH concentrations and ongoing pregnancy rates among normogonadotrophic patients undergoing ovarian stimulation in a gonadotrophin-releasing hormone antagonist protocol were examined. In the Engage trial, 1506 patients received corifollitropin alfa (150 μg) or daily recombinant FSH (rFSH) (200 IU) for the first 7 days of stimulation with 0.25mg ganirelix from stimulation day 5. Patients were retrospectively stratified by serum LH percentiles (< 25th, 25th-75th and >75th) on stimulation day 8 and day of human chorionic gonadotrophin administration. Odds ratios (OR) with and without adjustment for predictive factors for ongoing pregnancy were estimated. LH concentration was not associated with pregnancy rates in either treatment arm, in contrast to ovarian response and serum progesterone. With adjustment for these predictors and age, OR (95% confidence interval) for ongoing pregnancy on stimulation day 8 for LH categories < P25 versus ≥ P25, >P75 versus ≤ P75 and < P25 versus >P75 were 0.75 (0.53-1.06), 1.26 (0.87-1.83) and 0.70 (0.46-1.09) in the corifollitropin alfa arm and 0.80 (0.54-1.17), 1.28 (0.87-1.87) and 0.73 (0.46-1.16) in the rFSH arm respectively. There was also no significant difference in pregnancy rates between LH categories on day of human chorionic gonadotrophin administration with either treatment.     

Impact of high basal FSH/LH ratio in women with normal FSH levels on in vitro fertilization outcomes

Abstract

Basal luteinizing hormone (LH) levels have also been suggested to impact on ovarian responsiveness as well as basal follicular stimulating hormone (FSH) levels. The aim of this study was to compare the in vitro fertilization (IVF) outcomes according to cycle day 3 FSH/LH ratio and to assess the proper stimulation protocol between gonadotropin-releasing hormone (GnRH) agonist and GnRH antagonist protocols. The retrospective cohort study recruited a total of 1211 women having the laboratory values of FSH (<10?IU/L) and LH within 3 months before IVF. Patients were treated with GnRH agonist long or GnRH antagonist protocols and stimulated with recombinant FSH (rFSH). The number of total retrieved oocytes and mature oocytes, implantation rate, clinical pregnancy rate and ongoing pregnancy rate were analyzed between groups: Group I: FSH/LH?<?2 and Group II: FSH/LH?≥?2. The Group II had the small number of retrieved oocytes and mature oocytes compared to the Group I (p?=?0.000). Clinical and ongoing pregnancy rate were lower in Group II (p?=?0.006, 0.006, respectively). In comparison of each protocol within groups, Group II showed significantly low pregnancy rate when GnRH antagonist was administered. In women with normal FSH level, high day 3 FSH/LH ratio can present subclinically low ovarian reserve and be predictive of lower pregnancy outcomes in fresh IVF cycles, and the choice of GnRH agonist can be related to favorable IVF outcomes.     

Depot GnRH agonist versus the single dose GnRH antagonist regimen (cetrorelix, 3 mg) in patients undergoing assisted reproduction treatment

The objective of this study was to compare, in a centre with previous experience of gonadotrophin-releasing hormone (GnRH) antagonist use, single administration of a GnRH antagonist [cetrorelix (Cetrotide) 3 mg] with a single administration of a GnRH agonist [Decapeptyl Retard 3.75 mg] in patients undergoing assisted reproduction treatment (n = 307 and 364 respectively). GnRH agonist was administered on the first day of menses, while cetrorelix was administered when the largest follicle reached 14 mm. Ovarian stimulation was performed with recombinant human FSH (r-hFSH; 150-225 IU/day). Human chorionic gonadotrophin (HCG, 10,000 IU) was administered when at least two follicles reached a mean diameter > or =18 mm. Over 90% of patients in both groups reached the criteria for HCG administration and underwent oocyte retrieval and embryo transfer. Duration of FSH therapy (9.95 versus 11.25 days) and cumulative dose of r-hFSH (1604 versus 1980 IU) were significantly reduced (P < 0.01) in the cetrorelix 3 mg group. The number of oocytes retrieved was lower (8.5 versus 11.2; P < 0.01) with cetrorelix, but the number of embryos replaced was similar (2.2 versus 2.3; NS). The pregnancy rates per oocyte retrieval were the same, 24.5%, in the antagonist and agonist groups. This study indicates that although fewer oocytes are recovered, similar pregnancy rates can be achieved with a GnRH antagonist compared with a GnRH agonist. Additionally, a single dose of 3 mg cetrorelix was administered in 84% of patients, thus being simpler and more convenient for patients. Cetrorelix 3 mg may thus be proposed as a first choice for preventing both a premature LH surge and detrimental rises in LH during ovarian stimulation prior to assisted reproduction treatment.     

GnRH antagonist in older IVF patients. Retrieval rates and clinical outcome

OBJECTIVE: To determine if the use of a midcycle GnRH antagonist provides better clinical outcomes and lower cancellation rates in in vitro fertilization (IVF). STUDY DESIGN: We examined all patients older than 40 years undergoing IVF-embryo transfer cycles between January 1999 and December 2000. Prior to June 2000, controlled ovarian stimulation in women > or = 40 years was performed with follicle stimulating hormone (FSH)/human menopausal gonadotropin (hMG) only and no GnRH agonist or antagonist (group I). After June 2000, following the release of Ganirelix in the U.S., all women > or = 40 years were stimulated with FSH/hMG + Ganirelix (group II). Outcomes of IVF cycles prior to Ganirelix were compared to results after its introduction. RESULTS: Cancellation rates were significantly lower in group II (16%) as compared to group I (67%) (P < .05). In patients with oocytes retrieved, group II had a significantly higher number of recovered oocytes (7.7 +/- 0.8 vs. 5.3 +/- 0.7, P < .05). However, the number of embryos transferred, cumulative embryo scores, implantation rates and ongoing pregnancy rates did not differ significantly between groups. CONCLUSION: Although our results are preliminary, the addition of GnRH antagonist avoids ovarian suppression at the start of controlled ovarian hyperstimulation and prevents the premature LH surge at midcycle. Thus, more patients attempting IVF undergo oocyte retrieval, although clinical outcomes may not necessarily be improved.     

Role of LH in ovarian stimulation: considerations

The role of LH in ovarian stimulation continues to be controversial. Most observational studies on both gonadotrophin-releasing hormone (GnRH) agonist and GnRH antagonist protocols failed to show an effect on ongoing pregnancy likelihood of punctually measured 'low' or 'high' endogenous LH concentrations during ovarian stimulation. As yet, it is still unknown whether individual patients with strongly suppressed levels of immunoreactive LH would actually benefit from additional LH administration. This can only be explored by means of interventional trials. Most trials on LH supplementation in general populations in both GnRH agonist and GnRH antagonist protocols have not found a benefit of LH supplementation, although it has been indicated that some subgroups, such as older age patients, or patients with a low ovarian response might benefit from LH. These concepts need to be explored further before recommendations can be given as to in who, in what protocol, at what time point and in what doses LH should be supplemented.     

Premature luteinization during gonadotropin-releasing hormone antagonist cycles and its relationship with in vitro fertilization outcome

OBJECTIVE: To determine the prevalence and the effect of premature luteinization in GnRH antagonist IVF-ET cycles. DESIGN: Prospective observational study. SETTING: In vitro fertilization-embryo transfer (IVF-ET) program at the Instituto Valenciano de Infertilidad. PATIENT(S): Eighty-one infertile patients undergoing controlled ovarian hyperstimulation with gonadotropins and GnRH antagonist for IVF-ET. INTERVENTION(S): Gonadotropin-releasing hormone (GnRH) antagonist was administered from stimulation day 6. Serum P, E(2), and LH were determined on the day of hCG administration. MAIN OUTCOME MEASURE(S): Cycles were grouped according to serum P level on the day of hCG administration (<1.2 ng/mL or > or =1.2 ng/mL). Clinical pregnancy and implantation rates were determined. RESULT(S): The incidence of premature luteinization was 38.3%. Total recombinant FSH dose and stimulation days differed significantly between the groups. Pregnancy rate (25.8% vs. 54.0%) and implantation rate (13.8% vs. 32.0%) were significantly lower in the premature luteinization group. CONCLUSION(S): Premature luteinization during GnRH antagonist IVF-ET cycles is a frequent event that is associated with lower pregnancy and implantation rates. Progesterone elevations are not related to serum LH levels and may reflect the mature granulosa cell response to high FSH exposure.     

Exposure to high levels of luteinizing hormone and estradiol in the early follicular phase of gonadotropin-releasing hormone antagonist cycles is associated with a reduced chance of pregnancy

OBJECTIVE: To compare ongoing implantation rates under two different GnRH antagonist protocols. DESIGN: Randomized controlled trial. SETTING: Tertiary referral center. PATIENT(S): One hundred eleven women undergoing ovarian stimulation for in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). INTERVENTION(S): Ovarian stimulation with 150 IU recombinant-FSH (rec-FSH) starting on day 2 of the cycle and GnRH antagonist starting either on day 6 of stimulation (fixed group) or when a follicle of > or = 15 mm was present after at least 5 days of stimulation (flexible group). In the flexible group, the rec-FSH dose was increased to 250 IU when the antagonist was initiated. MAIN OUTCOME MEASURE(S): Ongoing implantation and pregnancy rate. RESULT(S): In patients with no follicle of > or = 15 mm present on day 6 of stimulation, a significantly lower ongoing implantation rate was observed if the flexible scheme was applied as compared with the fixed scheme of administration (8.8% vs. 23.9%, respectively). Exposure of the genital tract to LH or E2 from initiation of stimulation to antagonist administration was able to distinguish between pregnant and nonpregnant patients in the population studied. CONCLUSION(S): High exposure of the genital tract to LH and E2 in the early follicular phase is associated with a reduced chance of pregnancy in cycles stimulated with recombinant FSH and GnRH antagonist for IVF/ICSI.     

Reproductive outcome of polycystic ovarian syndrome patients treated with GnRH antagonists and recombinant FSH for IVF/ICSI

The purpose of this prospective study was to assess the reproductive outcome of patients with polycystic ovarian syndrome (PCOS) treated by in-vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) with recombinant FSH (rFSH) and gonadotrophin releasing hormone (GnRH) antagonists. One hundred and ten patients were evaluated. The starting dose of rFSH was 100 IU in 67 women with body mass index (BMI) 29 kg/m(2). GnRH antagonist was started by the detection of a follicle of a 15mm in ultrasound scan. A significantly lower ongoing pregnancy rate per oocyte retrieval (25.6% versus 46.7%, P = 0.04) and a higher occurrence of ovarian hyperstimulation syndrome (16.3% versus 3.0%, P = 0.03) was observed in the group of patients with BMI >29 kg/m(2) as compared with the group of patients with BMI 29 kg/m(2) in whom stimulation is initiated with 200 IU of rFSH as compared with PCOS patients with BMI 相似文献   

The decrease of serum luteinizing hormone level by a gonadotropin-releasing hormone antagonist following the mild IVF stimulation protocol for IVF and its clinical outcome

Purpose While performing the mild ovarian stimulation protocol with a GnRH antagonist, the pregnancy rate was compared between the groups, which were divided by the degree that the luteinizing hormone (LH) level decreased. Materials and methods Patients aged 27 to 42years (36.1 ± 3.79) underwent 308 IVF cycles who opted for IVF via the mild ovarian stimulation protocol began clomiphene citrate on day 3 and recombinant FSH on day 5. A GnRH antagonist was administered when the dominant follicle reached 14mm. Serum LH was measured at the time of GnRH antagonist administration and at the time of hCG injection. The pregnancy rate and implantation rate were compared between 50 cycles in which the LH level dropped less than one-third and the control (LH level within 1/3). Result(s) The pregnancy rate for the group in which the LH level fell less than one third was 18%. Conversely, the pregnancy rate for the control group was 39%. The implantation rate was 18% for the less than one-third group and 26% for the control group. Both the pregnancy rate and the implantation rate for the group in which the LH level fell less than one-third were significantly lower than that of control (p < 0.02). Conslusion(s) When performing the mild ovarian stimulation protocol, serum LH should be followed. If the serum LH level is less than one-third at the time of hCG injection, both the pregnancy rate and implantation rate are significantly lower. Capsule If the serum LH level is less than one-third at the time of hCG injection, both the pregnancy rate and implantation rate are significantly lower following the Mild IVF stimulation protocol.     

Use of GNRH antagonists in reproductive medicine

Gonadotrophin-releasing hormone (GnRH) plays a key role in the secretion of gonadotrophins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which regulate steroidogenesis and folliculogenesis. Two GnRH antagonists, Cetrorelix and Ganirelix, deprived of histaminergic side-effects, have been introduced into ovarian stimulation protocols to prevent premature LH surges and proved their safety in clinical trials. At present, most of the published studies have not found significant differences in follicular recruitment, oocyte quality, and so on, except for a decrease in pregnancy and implantation rates in in vitro fertilization and embryo transfer (IVF-ET) cycles when the GnRH antagonist rather than the agonist was used. This decrease in pregnancy rates was in relation with a necessary learning curve of the physicians. Another possibility is the impact of the GnRH antagonist on endometrium through its GnRH receptor; this effect was cancelled after cryopreserved embryo transfers because the pregnancy rates were similar between GnRH antagonist and agonist in this case. GnRH antagonists were also interesting in poor responders and polycystic ovarian syndrome, where the agonists have not permitted to obtain the better results in IVF-ET cycles. Similarly, the GnRH antagonists could prevent the LH surge in the intrauterine insemination cycles.     

Who needs LH in ovarian stimulation?

LH plays a key role in the intermediate-late phases of folliculogenesis. Although ovarian stimulation is efficiently achieved in most cases by the administration of exogenous FSH alone, specific subgroups of women may benefit from LH activity supplementation during ovarian stimulation. Some authors have found improved outcome with LH activity supplementation in advanced reproductive age women. Experience suggests that in about 10-12% of young normogonadotrophic patients treated with a gonadotrophin-releasing hormone agonist (GnRH-a) long protocol plus recombinant FSH human (r-hFSH), a 'steady response' is observed. In this subgroup of women, a higher number of oocytes is retrieved when daily LH activity supplementation is given from stimulation day 8, if compared with the standard FSH dose increase. Another subgroup of patients who may benefit from LH activity supplementation are those at risk for poor ovarian response treated with GnRH antagonist. Recent data demonstrate that in these women, when GnRH is administered in a flexible protocol, the concomitant addition of recombinant human LH improves the number of mature oocytes retrieved, when compared with the standard GnRH-a flare-up protocol. Thus, well calibrated LH administration improves the ovarian outcome in patients >35 years, in those showing an initial abnormal ovarian response to r-hFSH monotherapy, and in 'low prognosis' women treated with GnRH antagonists.     

Concurrent ganirelix and follitropin beta therapy is an effective and safe regimen for ovulation induction in women with polycystic ovary syndrome

OBJECTIVE: To evaluate controlled ovarian stimulation cycles using the GnRH antagonist ganirelix in combination with the recombinant FSH, follitropin-beta, in women with polycystic ovary syndrome (PCOS). DESIGN: Prospective, nonrandomized clinical study. SETTING: Hospital-based infertility practice. PATIENT(S): Twenty women with PCOS planning to undergo ovarian stimulation. INTERVENTION(S): Fasting glucose and insulin levels were used to calculate insulin resistance ratios (FG/I). After pretreatment with oral contraceptives, serum LH levels were determined, and 250 microg ganirelix was administered on cycle day 2. Upon suppression of LH, concurrent ganirelix and follitropin-beta therapy (morning ganirelix and evening follitropin-beta) was started and continued until the day of hCG. MAIN OUTCOME MEASURES: Days of stimulation, dose of follitropin-beta, pregnancy, and ongoing pregnancy were compared based on FG/I ratios. RESULTS: One dose of ganirelix effectively suppressed LH levels in all patients. All patients ovulated as documented by a rise in progesterone. Significant differences were observed between the insulin-resistant and non-insulin-resistant groups for both days of stimulation and dose of follitropin-beta. The overall clinical pregnancy rate was 44.4%, with an ongoing pregnancy rate of 27.8%. CONCLUSIONS: In this preliminary study, we demonstrate the effectiveness of a concurrent ganirelix and follitropin-beta therapy for ovarian stimulation in women with PCOS.     

Luteinizing hormone concentrations after gonadotropin-releasing hormone antagonist administration do not influence pregnancy rates in in vitro fertilization-embryo transfer

OBJECTIVE: To determine the impact of circulating LH concentrations during controlled ovarian hyperstimulation on the outcome of IVF. DESIGN: Retrospective study. SETTING: University hospital. PATIENT(S): Two-hundred seventy women who had a short stimulation protocol with GnRH antagonist and ovarian stimulation with recombinant FSH (rFSH). INTERVENTION(S): GnRH antagonist and rFSH were administered SC; blood samples were collected on the day of GnRH antagonist administration, 1 day after, and on the day of hCG administration. MAIN OUTCOME MEASURE(S): A threshold of 0.5 IU/L on the day of hCG was chosen to discriminate between women with LH concentrations 0.5 IU/L (group B, n = 151). RESULT(S): The two groups were comparable with regard to the clinical parameters. In group A, significantly lower LH concentrations were observed on day 9 of the cycle and on the day of hCG administration. The numbers of oocytes retrieved, embryos obtained, and embryos cryopreserved were significantly higher in group A compared with group B. The proportion of clinical pregnancies was similar in the two groups (21.1% vs. 22.7 % per ET). CONCLUSION(S): In GnRH antagonist and rFSH protocols, suppressed serum LH concentrations do not have any influence on the final stages of follicular maturation, pregnancy rates, or outcomes.     

Outlook: who needs LH in ovarian stimulation?

LH plays a key role in the intermediate-late phases of folliculogenesis. Although ovarian stimulation is efficiently achieved in most cases by the administration of exogenous FSH alone, specific subgroups of women may benefit from LH activity supplementation during ovarian stimulation. Some authors have found improved outcome with LH activity supplementation in advanced reproductive age women. Experience suggests that in about 10-12% of young normogonadotrophic patients treated with a gonadotrophin-releasing hormone agonist (GnRH-a) long protocol plus recombinant FSH human (r-hFSH), a 'steady response' is observed. In this subgroup of women, a higher number of oocytes is retrieved when daily LH activity supplementation is given from stimulation day 8, if compared with the standard FSH dose increase. Another subgroup of patients who may benefit from LH activity supplementation are those at risk for poor ovarian response treated with GnRH antagonist. Recent data demonstrate that in these women, when GnRH is administered in a flexible protocol, the concomitant addition of recombinant human LH improves the number of mature oocytes retrieved, when compared with the standard GnRH-a flare-up protocol. Thus, well calibrated LH administration improves the ovarian outcome in patients >35 years, in those showing an initial abnormal ovarian response to r-hFSH monotherapy, and in 'low prognosis' women treated with GnRH antagonists.     

Serum luteinizing hormone in patients undergoing ovarian stimulation with gonadotropin-releasing hormone antagonists and recombinant follicle-stimulating hormone and its relationship with cycle outcome

The serum LH was determined on days 3, 6, and 8 of stimulation and on the day of hCG in 110 normogonadotropic patients undergoing controlled ovarian hyperstimulation (COH) for IVF induced with GnRH antagonists and recombinant FSH, creating three groups of patients according to Tukey's hinges (percentiles 25 and 75) for each determination. No differences were observed between the number of oocytes recovered or the fertilization, implantation, and pregnancy rates (PR) of the groups, although patients with high serum LH levels during stimulation showed significantly higher serum E2 levels on the day of hCG.     

First live birth after ovarian stimulation using a chimeric long-acting human recombinant follicle-stimulating hormone (FSH) agonist (recFSH-CTP) for in vitro fertilization

OBJECTIVE: To report the first pregnancy and live birth after ovarian stimulation using a chimeric long-acting human recombinant FSH agonist (recFSH-CTP) for IVF. DESIGN: Case report. SETTING: Tertiary fertility center. PATIENT(S): A 32-year-old woman with a 7-year history of primary infertility. INTERVENTION(S): Ovarian stimulation with a single SC injection of 180 microg recFSH-CTP on cycle day 3, followed by daily injections of 150 IU recFSH from cycle day 10 onward, combined with daily GnRH antagonist 0.25 mg SC to prevent a premature LH rise. Final oocyte maturation was induced by 10,000 IU hCG. MAIN OUTCOME MEASURE(S): First ongoing pregnancy obtained with recFSH-CTP. RESULT(S): Twelve oocytes were retrieved. Ten oocytes were fertilized in vitro by intracytoplasmic sperm injection, and from these 10 oocytes, two embryos were subsequently transferred after 3 days of culture. A pregnancy test 2 weeks after ET was positive, and ultrasound investigation revealed an intact, intrauterine, singleton pregnancy after 12 weeks. CONCLUSION(S): The first pregnancy and live birth was achieved after ovarian stimulation using recFSH-CTP for IVF.     

Role of periovulatory luteinizing hormone concentrations during assisted reproductive technology cycles stimulated exclusively with recombinant follicle-stimulating hormone

OBJECTIVE: To study the effect of endogenous luteinizing hormone (LH) concentration on fertilization, pregnancy, and early pregnancy loss rates. DESIGN: Retrospective cohort study. SETTING: Tertiary-care university center. PATIENT(S): One hundred sixty-six normogonadotropic patients undergoing IVF. INTERVENTION(S): Luteal phase pituitary down-regulation and recombinant FSH (Gonal-F) were used for ovarian stimulation. The mean of 4-5 serum LH concentrations, from stimulation days 5-12, was computed for analysis. MAIN OUTCOME MEASURE(S): Fertilization, pregnancy, and early pregnancy loss rates according to periovulatory levels of LH. RESULT(S): Data were analyzed by stratifying patients according to a mean periovulatory LH value of 3 mIU/mL. After controlling for confounding variables with logistic regression, results showed that the fertilization rate was significantly lower in patients with a periovulatory LH <3 mIU/mL versus > or = 3 mIU/mL (52% and 58%, respectively; P=.03). Pregnancy rates and spontaneous abortion rates were similar in both groups. There were seven biochemical pregnancies, all in patients with an LH <3 mIU/mL (P=.07). CONCLUSION(S): Low endogenous LH concentrations (<3 mIU/mL) in the late follicular phase of an IVF cycle are associated with significantly lower fertilization rates and a trend toward higher biochemical pregnancy rates. It may be of clinical benefit, when exclusively using r-hFSH in ART cycles, to add LH in the late follicular phase or to further reduce the dose of GnRH agonist.     

A modified gonadotropin-releasing hormone (GnRH) antagonist protocol failed to increase clinical pregnancy rates in comparison with the long GnRH protocol

The purpose of this prospective randomized study was to compare stimulation characteristics and IVF outcomes of the standard long GnRH agonist protocol for ovarian stimulation with a modified GnRH antagonist protocol. Starting GnRH antagonist in a flexible protocol according to the size of the leading follicle, with simultaneous augmentation of 75 IU recombinant FSH, failed to increase clinical pregnancy rates.     

Effect of an oral contraceptive pill on follicular development in IVF/ICSI patients receiving a GnRH antagonist: a randomized study

This randomized controlled study compared the effectiveness of a gonadotrophin releasing hormone (GnRH) antagonist protocol with or without oral contraceptive (OC) pretreatment on the number of oocytes retrieved in IVF or intracytoplasmic sperm injection (ICSI) patients. Sixty-four patients were randomized to start recombinant human FSH (r-hFSH) on day 2 or 3 after OC withdrawal (OC group) or on day 2 of a natural cycle (control group). From stimulation day 6 onwards, all patients were treated with daily (0.5 mg/ml) GnRH antagonist (Antide). OC pretreatment resulted in significantly lower starting concentrations of FSH, LH and oestradiol (P < 0.001) and a thinner endometrium (P < 0.0001). In the early stimulation period, fewer large follicles were found after OC pretreatment, leading to a significantly extended stimulation period (11.6 versus 8.7 days, P < 0.0001) with more follicles on the day of recombinant human chorionic gonadotrophin administration (15.4 versus 12.5, P = 0.02) and more oocytes retrieved (13.5 versus 10.2, P < 0.001) as compared with the control group. GnRH antagonist regimen, pretreated with OC, prevented the early endogenous FSH rise and improved follicular homogeneity, resulting in more oocytes. As a consequence of the extended treatment period, more rhFSH was required.     

Effect of ovarian stimulation with recombinant follicle-stimulating hormone,gonadotropin releasing hormone antagonists,and human chorionic gonadotropin on endometrial maturation on the day of oocyte pick-up

OBJECTIVE: To assess the effect of ovarian stimulation with recombinant FSH, GnRH antagonists, and hCG on endometrial maturation on the day of oocyte pick-up. DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENT(S): Fifty-five women undergoing controlled ovarian hyperstimulation for IVF/intracytoplasmic sperm injection (ICSI). INTERVENTION(S): [1] Ovarian stimulation with recombinant FSH, starting on day 2 of the cycle and GnRH antagonist, starting after a median of 6 days of recombinant FSH stimulation (range, 5-12 days); [2] hCG administration for ovulation induction; and [3] aspirational biopsy of endometrium at oocyte pick-up. MAIN OUTCOME MEASURE(S): Endometrial histology at oocyte pick-up by Noyes criteria. RESULT(S): Advancement of endometrial maturation (2.5 +/- 0.1 days) as compared to the expected chronological date was observed in all antagonist cycles at oocyte retrieval. Endometrial advancement at oocyte pick-up increased in line with values of LH at initiation of stimulation and the duration of recombinant FSH treatment before the antagonist was started. CONCLUSION(S): The higher the values of LH at initiation of stimulation and the longer the duration of recombinant FSH treatment before the antagonist is started, the more advanced the endometrial maturation at oocyte pick-up.