Endocrine changes in the late-follicular and postovulatory intervals as determinants of the in vitro fertilization pregnancy rate

This investigation examines the hormone pattern in in vitro fertilization (IVF) cycles from the time of human chorionic gonadotropin (hCG) administration through embryo transfer to ascertain whether the absolute levels or secretory patterns of the major reproductive hormones affect the IVF pregnancy rate. Thirty-one women who underwent IVF treatment were enrolled in the study. All patients received clomiphene citrate/human menopausal gonadotropin for ovulation induction. Significant elevations in serum estradiol (E2) levels in the pregnant group were found throughout the cycle interval studied. After hCG administration the serum hCG levels were not different between the groups. Significant elevations in serum progesterone (P) concentrations were found in the pregnant group from the day after laparoscopy through embryo transfer. Embryos obtained from the pregnant group appeared to be different in that the mean number of blastomeres per embryo transferred was significantly greater. Therefore for achievement of an IVF pregnancy the optimal hormone pattern employing combination ovulation induction in the ovulation to transfer interval is a relatively high E2 level in ovulation followed by a high P level at transfer and into the luteal phase. These elevated hormone levels do not depend on the response to exogenous hCG.     

The importance of human chorionic gonadotropin support of the corpus luteum during human gonadotropin therapy in women with anovulatory infertility

One hundred ten women with anovulatory infertility (World Health Organization [WHO] group I n = 50, WHO group II n = 60) were given 341 treatment courses with human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG). Additional hCG was given as single or repeated injections during the luteal phase in 205 ovulatory cycles. In WHO group I, the incidence of luteal phase defects was lower and the pregnancy rate higher in cycles with extra hCG administration during the luteal phase than in cycles with no extra hCG. In WHO group II, there was no such difference after supplemental hCG. The abortion rate was the same after cycles with or without extra hCG administration. It is suggested that during ovulation induction with hMG/hCG in anovulatory women with no evidence of endogenous estrogen activity, the luteal phase should be supplemented with additional hCG.     

Luteal phase support with hCG does not improve fecundity rate in human menopausal gonadotropin-stimulated cycles.

The luteal phase of cycles stimulated with human menopausal gonadotropins (hMG) may be characterized by aberrant hormone levels, altered endometrial development, and shortened length. Luteal phase support with supplemental progesterone or hCG has been recommended to help correct these problems and thus improve pregnancy rates, but the efficacy of such regimens is controversial. Therefore, a randomized cross-over study was performed to evaluate the effects of luteal phase hCG administration on pregnancy rates during ovulation induction with hMG. Sixty-seven infertile women were randomly assigned to either group A (N = 33) or group B (N = 34). Non-treatment cycles (no luteal phase support) were alternated with treatment cycles, in which patients received 2500 IU hCG on the third, sixth, and ninth days after the ovulatory dose of 10,000 IU hCG. Patients in group A received supplemental hCG in odd-numbered cycles, whereas group B was given luteal support in even-numbered cycles. The mean number of cycles per patient was 2.2 and 2.3 for groups A and B, respectively. Analysis of 151 cycles revealed a cycle fecundity of 0.15 for 72 hCG-supported cycles, versus 0.13 for 79 nonsupported cycles (P = not significant). Midluteal progesterone levels were significantly higher in supported (45.6 ng/mL) versus unsupported cycles (31.9 ng/mL) (P less than .001). There were no significant differences in the mean peak estradiol levels in hCG-supported versus -unsupported cycles. We conclude that hCG support of the luteal phase is not routinely warranted in hMG-stimulated cycles.     

Luteal phase support in in vitro fertilization: meta-analysis of randomized trials

OBJECTIVE: To determine if luteal phase support improves the pregnancy rate in in vitro fertilization (IVF) cycles. DESIGN: A meta-analysis of randomized trials of luteal phase support was carried out with the main outcome measure being the pregnancy rate per cycle. RESULTS: Fifty-nine trials were evaluated. Eighteen trials met the inclusion criteria. Five main themes were identified: human chorionic gonadotropin (hCG) versus progesterone; progesterone versus progesterone and hCG; progesterone versus placebo; hCG versus placebo, and hCG versus progesterone versus no support. CONCLUSION: Luteal phase support is definitely indicated in IVF treatment cycles. This meta-analysis favored hCG above progesterone as luteal phase support with respect to pregnancy rates. Further prospective randomized trials are needed to determine a definite consensus with respect to the duration of luteal phase support in IVF cycles.     

Progesterone levels on the day of human chorionic gonadotropin administration in cycles with gonadotropin-releasing hormone agonist suppression are not predictive of pregnancy outcome

In in vitro fertilization (IVF) cycles using gonadotropin-releasing hormone agonist (GnRH-a) suppression, we investigated whether an elevated progesterone (P) level on the day of human chorionic gonadotropin (hCG) administration indicates premature luteinization and is associated with a lower pregnancy rate. We retrospectively studied 101 patients treated with the GnRH-a leuprolide acetate, begun in the luteal phase of the prior menstrual cycle and continued until the day of hCG administration. On the day of hCG, 72 patients had P less than 0.9 ng/mL and 29 had less than or equal to 0.9 ng/mL. Patients in the high P group had a significantly greater estradiol level on the day of hCG. No significant difference in clinical pregnancy rates or ongoing pregnancy rates occurred between the low P and high P groups. We conclude that in IVF cycles pretreated with GnRH-a, P levels on the day of hCG are not predictive of conceiving in that cycle.     

Gonadotropin-releasing hormone agonist versus human chorionic gonadotropin for triggering follicular maturation in in vitro fertilization.

OBJECTIVE: To compare the use of gonadotropin-releasing hormone agonist (GnRH-a) with human chorionic gonadotropin (hCG) for triggering the final stage of follicular maturation for in vitro fertilization (IVF). DESIGN: In vitro fertilization outcome was determined in a randomized, prospective study. SETTING: The University of Toronto IVF program at The Toronto Hospital, Toronto General Division. PATIENTS AND INTERVENTIONS: One hundred seventy-nine women in the IVF program were given a subcutaneous injection of leuprolide acetate (500 micrograms) or an intramuscular injection of hCG (5,000 IU) 34 to 36 hours before oocyte retrieval. Vaginal progesterone (P) suppositories (50 mg) were used two times a day for luteal phase support. A subgroup of 41 women had serum estradiol (E2) and P levels determined 2 and 7 days after embryo transfer (ET). MAIN OUTCOME MEASURES: Pregnancy rates and luteal phase E2 and P were compared. RESULTS: In the GnRH-a group, there were 18 pregnancies from 84 ETs (20%). In the hCG group, there were 19 pregnancies from 95 ETs (19%). Luteal phase E2 and P levels were significantly lower in the GnRH-a group compared with the hCG group, and 18% of the former group had an apparent short luteal phase. CONCLUSIONS: Gonadotropin-releasing hormone agonist appears to be an effective alternative to hCG for inducing follicular maturation in IVF. The lower luteal phase E2 concentrations may potentially be beneficial in preventing ovarian hyperstimulation and for enhancing implantation. Better luteal phase support or a different dose of GnRH-a is needed to prevent luteal phase deficiency.     

Luteal function following ovarian stimulation in rhesus monkeys for in vitro fertilization: atypical response to human chorionic gonadotropin treatment simulating early pregnancy

This study determined if corpora lutea of hyperstimulated cycles in rhesus monkeys could be "rescued" by the pregnancy signal, chorionic gonadotropin (CG), given at the typical time of implantation. At menses, female monkeys received human follicle-stimulating hormone (hFSH, 60 IU, days 1 to 6) followed by human menopausal gonadotropin (hMG, 60 IU hFSH/60 IU luteinizing hormone [hLH], days 7 to 9). On day 10, human chorionic gonadotropin (hCG) was given to mimic the LH surge. Nine days later, a regimen of daily increasing doses of hCG (15 to 360 IU twice a day) was initiated to simulate rescue of the corpus luteum in early pregnancy. Serum levels of progesterone (P) increased through day 5 of the luteal phase but then declined. Circulating levels of bioactive LH were significantly less on days 7 to 9 of the luteal phase than at this stage in the natural cycle. The hCG regimen extended (P less than 0.05) the luteal phase in five of six animals. The hCG treatment elicited a persistent increase (P less than 0.05) in circulating P levels, rather than a transient rise typical of normal or simulated pregnancy in natural cycles. The authors conclude that (1) corpora lutea of hyperstimulated cycles can respond to CG, but (2) there are differences in luteal function during both the luteal phase and simulated early pregnancy that may be due to inadequate luteal development or the abnormal gonadotropin milieu existing after ovulation or both.     

Luteal dysfunction in ovulation induction: the role of repetitive human chorionic gonadotropin supplementation during the luteal phase

Several studies have indicated that ovulation induction with human menopausal gonadotropin (hMG)/human chorionic gonadotropin (hCG) or clomiphene citrate (CC) is associated with luteal phase defect. To assess the efficiency of luteal support by hCG to an infertile population undergoing ovulation induction, with CC/hCG or hMG/hCG, we have randomly administered 2500 IU hCG intramuscularly on days 3, 6, and 9 after ovulation induction by 10,000 IU of hCG to 74 patients on 265 treatment cycles. As controls served 357 ovulation induction cycles in the same 74 patients. The treatment cycles were randomly alternated with control cycles so that each patient served as her own control. However, the mean +/- standard deviation (SD) midluteal P was 38.1 +/- 10.8 ng/ml in the study group versus 15.7 +/- 10.5 ng/ml in the control group (P less than 0.001). Luteal phase length was 15.4 +/- 1.5 days in the treatment group versus 12.1 +/- 1.7 in the control group (P less than 0.01). In the treatment group, 64.8% of the patients achieved pregnancy (27% pregnancies/treatment cycle) versus 47.3% in the control group (11.5% pregnancies/control cycle) (P less than 0.01). The pregnancy wastage rates (including abortions and "chemical" pregnancies) were 30.6% in the treatment group versus 56% in the control group (P less than 0.01). We conclude that repetitive hCG administration may be an efficient luteal support in infertile patients undergoing ovulation induction.     

Estradiol supplementation during the luteal phase may improve the pregnancy rate in patients undergoing in vitro fertilization-embryo transfer cycles

OBJECTIVE: To evaluate the effect of adding E(2) to progestin supplementation during the luteal phase on pregnancy and implantation rates in patients undergoing IVF cycles. DESIGN: Prospective, randomized study.Setting: An IVF unit in a university hospital. PATIENT(s): Patients who were undergoing IVF with controlled ovarian hyperstimulation using a GnRH analog and who had E(2)2,500 pg/dL at the time of hCG administration. INTERVENTION(s): Serum concentrations of E(2) and progesterone were measured in all patients on days 7, 10, and 12 after ET. MAIN OUTCOME MEASURE(s): The E(2) and progesterone profiles of the luteal phase and the pregnancy and implantation rates were documented. Data were analyzed for the entire study population and further stratified according to the GnRH analog protocol used (short or long). RESULT(s): Significantly higher E(2) levels were found during the luteal phase in the group that received E(2) supplementation. This effect was more pronounced in the patients who were treated with the long GnRH analog protocol. Significantly higher pregnancy and implantation rates were recorded in the patients who received E(2) supplementation and were treated with the long GnRH analog protocol. CONCLUSION(s): For patients who are treated with the long GnRH analog protocol for controlled ovarian hyperstimulation and for whom luteal support with hCG is contraindicated, the addition of E(2) to the progestin support regimen may have a beneficial effect on pregnancy and implantation rates.     

Luteal support after luteinizing hormone-releasing hormone agonist for in vitro fertilization: superiority of human chorionic gonadotropin over oral progesterone

It has been reported that the pregnancy rate after in vitro fertilization (IVF) after pituitary desensitization with luteinizing hormone-releasing hormone agonist (LH-RH-a) is twice as low if the luteal phase is not supported. We therefore tested the respective advantages of luteal support using human chorionic gonadotropin (hCG, 1,500 IU three times) and progesterone (P, micronized, oral administration, 400 mg/d) after 171 embryo transfers (ET) in which the cycle was stimulated with the LH-RH-a triptoreline. The type of luteal phase support was randomly selected except when the estradiol level exceeded 2,700 pg/mL. The clinical pregnancy rate and the ongoing pregnancy rate were significantly higher using hCG (after the transfer of 3 embryos, 45% and 43% with hCG versus 23% and 17% with P). The same results were noted for the embryo implantation rate per ET (19% of embryos are viable after 6 months of pregnancy after hCG versus 7.5% after P). Adequate luteal support, therefore, significantly improves the results of IVF when LH-RH-a are used. The poor results obtained with P in this study might be related to its poor bioavailability after oral administration.     

Evidence for an adverse effect of elevated serum estradiol concentrations on embryo implantation

Multiple follicular stimulation for IVF may be associated with greatly elevated serum E2 concentrations that are presumed to be antinidatory. This factor was analyzed in 825 consecutive embryo transfer cycles. The pregnancy rate decreased significantly after the transfer of one and two embryos in association with preovulatory E2 levels greater than the 90th percentile for the group (2320 pg/ml). The pregnancy rate did not vary with preovulatory E2 concentration following the transfer of three embryos. Highly significant correlations were noted between preovulatory E2 and early luteal phase concentrations of E2 and P. In a subgroup of 245 cycles, there were no significant relationships between implantation and early luteal phase levels of P or the ratio of E2/P. There was a small but nonsignificant tendency for the pregnancy rate to decrease in association with raised luteal E2. It is concluded that excessive E2 levels at the time of ovulation induction with hCG had an adverse effect on implantation when one or two embryos are transferred, but this may be overcome by the transfer of three embryos. The consequences for embryo transfer are discussed.     

Pregnancy rate and ovarian hyperstimulation after luteal human chorionic gonadotropin in in vitro fertilization stimulated with gonadotropin-releasing hormone analog and menotropins

The value of luteal phase supplementation with human chorionic gonadotropin (hCG) was assessed after a combined protocol of ovarian stimulation, using a long acting gonadotropin releasing hormone analog (GnRH-a) and human menopausal gonadotropins (hMG), in a randomized prospective study of 36 consecutive cycles in an in vitro fertilization (IVF) program. The patients were allocated on the transfer day to either luteal phase supplementation with hCG (Group A, n = 18) or none (Group B, n = 18). Nine patients of Group A conceived as compared with 3 in Group B. Five patients, all in Group A, developed ovarian hyperstimulation syndrome (OHSS) (3 moderate and 2 severe forms). Analysis of the hormonal profiles disclosed similar progesterone (P), estradiol (E2), and E2/P ratio up to the 6th post ovum pick-up day. Then, E2 and mainly P levels decreased only in Group B resulting in a rising E2/P ratio. These findings stress the importance of luteal support in IVF cycles treated with GnRH-a. In light of the increased risk of OHSS among hCG treated patients, further studies are needed to assess the optimal preparation needed.     

三种促排卵方案对卵巢储备力低下患者助孕效果比较

目的:探讨卵巢储备力低下患者行体外受精/卵胞浆内单精子显微注射-胚胎移植(IVF/ICSI-ET)助孕时较理想的超促排卵方案。方法:将302例行IVF/ICSI-ET助孕的卵巢储备力低下患者分为3组:微刺激方案组(A组,98例)、黄体期促排卵方案组(B组,62例)和超短方案组(C组,142例),比较3组的一般情况、周期取消率、总促性腺激素释放激素(Gn)使用天数(Gn天数)、人绒毛膜促性腺激素(HCG)日血雌二醇(E_2)、促黄体生成素(LH)、孕酮(P)及子宫内膜厚度、平均获卵数、受精率、形成胚胎率、优质胚胎率、临床妊娠率、生化妊娠率。结果:A组的周期取消率均明显高于B、C两组(P0.05);A组的总Gn天数最短,C组的总Gn天数最长(P0.05);A组的HCG日子宫内膜厚度低于B、C组,但差异无统计学意义;A组的HCG日E_2水平、平均获卵数均低于B、C两组,C组的HCG日LH水平均低于A、B两组(P0.05)。3组的一般情况、正常受精率、成胚率、优胚率、临床妊娠率、生化妊娠率均无统计学差异。结论:超短方案可能是较好的卵巢储备力低下超促排卵方案,同时黄体期促排卵亦不失为一种新的有效促排卵方案。     

Human chorionic gonadotropin combined with progesterone for luteal support improves pregnancy rate in patients with low late-midluteal estradiol levels in IVF cycles

Purpose : To investigate how late-midluteal estradiol levels relate to the pregnancy outcome in IVF cycles, and to assess whether human chorionic gonadotropin (hCG) for luteal support benefits the pregnancy outcome of patients with low late-midluteal estradiol levels. Methods : The pregnancy rate of 436 women undergoing first IVF cycles with long protocol and luteal support with progesterone alone were analyzed. Unsuccessful women with low late-midluteal estradiol levels (<100 pg/mL) proceeded with the exploratory second IVF cycles where they were randomly given with either progesterone alone (P protocol) or hCG +progesterone (P+hCG protocol) for luteal support. Results : Pregnancy rate in women with low late-midluteal estradiol levels was significantly lower compared to that with medium (100–500 pg/mL) and high (>500 pg/mL) levels (13.3, 26.8, and 36.3%, respectively). P+hCG protocol increased late-midluteal estradiol levels and produced a significantly higher pregnancy rate (31.7%) than P protocol (13.7%). Conclusions : hCG in combination with progesterone for luteal support was suggested to benefit women undergoing IVF with low late-midluteal estradiol levels.     

The luteal phase during gonadotropin therapy: effects of two human chorionic gonadotropin regimens

OBJECTIVE: Luteal phase abnormalities are known to complicate ovulation induction with gonadotropins. This study was performed to test the effect of a modified human chorionic gonadotropin (hCG) regimen on the luteal phase during gonadotropin treatment. DESIGN: Fifteen women from a private practice setting volunteered to be studied during each of two nonconception, gonadotropin-stimulated cycles. After ovarian stimulation with human menopausal gonadotropins (hMG), hCG was administered either as a single dose of 10,000 IU (single dose) or in two divided doses of 5,000 IU given 1 week apart (split dose). MAIN OUTCOME MEASURES: Early, midluteal, and late luteal estradiol (E2) and progesterone (P) levels and luteal phase lengths were measured, and their median values and intraquartile ranges (IQR) compared using nonparametric analysis. RESULTS: Early and midluteal E2 and P levels were similar regardless of which hCG regimen was administered. The median late luteal E2 level was 1,146.0 pg/mL (the IQR ranged from 633 to 1,650, IQR = 1,017) with the split-dose regimen and 240.0 pg/mL (the IQR ranged from 150 to 460, IQR = 310) with the single-dose regimen. The median late luteal P level was 108.0 ng/mL (the IQR ranged from 58.5 to 129, IQR = 70.5) with the split-dose regimen and 4.2 ng/mL (the IQR ranged from 1.9 to 11.7, IQR = 9.8) with the single-dose regimen. Median luteal phase lengths were 16 days (the IQR ranged from 15 to 17, IQR = 2) for the split-dose regimen and 11 days (the IQR ranged from 10 to 12, IQR = 2) for the single-dose regimen. CONCLUSION: In hMG-stimulated cycles, a second dose of hCG given during the midluteal phase significantly increases late luteal E2 and P levels and consistently lengthens the luteal phase.     

A modest increase in serum progesterone levels on the day of human chorionic gonadotropin (hCG administration may influence pregnancy rate and pregnancy loss in in vitro fertilization-embryo transfer (IVF-ET) patients

Purpose Our purpose was to study the effect of a modest increase in preovulatory serum progesterone (P₄) levels in hyperstimulated patients and its association with pregnancy rate and pregnancy loss following in vitro fertilization (IVF) and embryo transfer (ET).Patients Only patients with mechanical factor and three transferred embryos were included in the present study. They were divided into two groups according to two critical breakpoints for P₄ serum levels on the day of hCG administration: serum P₄ below 0.6 ng/ml in 28 cycles (group I) and >0.6 ng/ml in 80 cycles (group II).Setting The setting was the IVF program at Carmel Medical Center, Haifa, Israel.Results The pregnancy rate per embryo transfer was 53% (15/28) in group I and 10% (8/80) in group II (P < 0.025). Of 15 pregnancies achieved in group I, 14 were ongoing pregnancies, compared to 4 of 8 ongoing pregnancies in group II (P <0.03). Conclusions Our findings suggest that a very modest increase in serum P₄ levels on the day of hCG administration is associated with lower pregnancy and ongoing pregnancy rates in IVF-ET.     

黄体期使用促性腺激素释放激素激动剂的效果评价

由于控制性超促排卵(COH)过程中超剂量雌、孕激素的生成以及垂体降调节药物的使用,经常出现黄体功能不全,需要常规进行黄体支持,常见的黄体支持方案包括使用人绒毛膜促性激素(hCG)及补充雌孕激素等。在近些年,多项研究表明促性腺激素释放激素激动剂(GnRH-a)在黄体支持中有很多积极方面,可以改善临床结局。其主要机制尚不清楚,可能与刺激黄体分泌雌、孕激素,提高子宫内膜容受性,提高胚胎发育潜能,促进滋养细胞分泌hCG相关。GnRHa进行黄体支持的机制及用法用量还有待进一步探究。     

不同黄体支持方法对体外受精-胚胎移植结果的影响

目的:探讨三种黄体支持方法对体外受精-胚胎移植(IVF-ET)结果的影响。方法:回顾性分析195个IVF-ET周期的结果,根据注射hCG当天的血E2水平、B超示直径≥14 mm卵泡数目及所用的黄体支持方法分组。A组:112例,E2<2 000 pg/mL,直径≥14 mm的卵泡数<10个,hCG进行黄体支持;对E2≥2 000 pg/mL,卵泡数目≥10个者,随机分为两组,B组,46例,单用黄体酮进行黄体支持;C组,37例,黄体酮加雌激素进行黄体支持。结果: 三组间妊娠率、种植率、流产率、OHSS发生率差异均无显著性,P>0.05。结论:hCG用于IVF黄体支持并不优于黄体酮,但在一定程度上可避免某些患者由于注射黄体酮产生的痛苦。黄体酮+雌激素进行黄体支持应该是黄体支持较合理的方案,还需进一步研究。     

Altered follicular development in clomiphene citrate versus human menopausal gonadotropin-stimulated cycles for in vitro fertilization

The pattern of periovulatory and luteal phase serum estradiol (E2) and progesterone (P) as well as follicular fluid (FF) E2, P, androgen, gonadotropin, and prolactin concentrations of eight women undergoing clomiphene citrate (CC)/human chorionic gonadotropin (hCG) stimulation and eight women undergoing human menopausal gonadotropin (hMG)/hCG stimulation of follicular development for the purpose of in vitro fertilization were compared. Ovulation was induced with either a 5-day course of CC (100 mg/day beginning on day 5 of the cycle) or an individualized hMG regimen, and laparoscopy was performed 36 hours after hCG administration. The length of the luteal phase was significantly longer (P less than 0.05) in the CC-treated group as compared with the hMG-treated group. The pattern of serum E2 levels differed significantly (P less than 0.01) in that E2 levels were lower in the early and midluteal phase in CC-stimulated cycles; in addition, a delayed second E2 peak was observed in the late luteal phase in these women. Serum P levels, however, were lower in the hMG-stimulated group. Analysis of FF hormone concentrations revealed significantly (P less than 0.05) higher concentrations of E2 and androsterone in the FF of hMG-treated patients. It is concluded that follicular development in CC-stimulated cycles differs markedly from that in hMG-stimulated cycles. These differences may reflect either an altered follicular maturational process or may represent a direct inhibitory effect of CC on follicular steroidogenesis.     

Which luteal phase support is better for each IVF stimulation protocol to achieve the highest pregnancy rate? A superiority randomized clinical trial

In vitro fertilization (IVF) cycles generate abnormalities in luteal-phase sex steroid concentrations and this represent an important limiting factor to achieve a good pregnancy rate. Although there are evidences about the usefulness of luteal phase support (LPS) after IVF cycles, no consensus exist about the best dose and way of progesterone (PG) administration, the advantages of estradiol (E2) supplementation and which IVF protocol could benefit from one more than other LPS scheme. Aim of the study was to assess the best LPS (low-dose PG, high-dose PG, high-dose PG and E2 supplementation) to achieve the highest clinical/ongoing pregnancy rate according to stimulation protocol, E2 at ovulation induction, endometrial thickness at pick-up and women’s age. We conducted a randomized trial on 360 women undergoing IVF (180 treated by long-GnRH agonist, 90 by short-GnRH agonist and 90 by short-GnRH antagonist protocol) and stimulated by recombinant follicle-stimulating hormone alone. Our data demonstrated that high-dose PG is better than low-dose to increase both clinical and ongoing pregnancy rate. E2 supplementation are mandatory in case of short-GnRH antagonist protocol and strongly suggested in all protocols when E2_max <5?nmol/l and endometrial thickness <10?mm. In long-GnRH agonist protocols, as well as in patients >35 years, the real advantages of E2 supplementation remain debatable and require further confirmation.