Dual-trigger for final oocyte maturation has been applied on the women with poor ovarian response or diminished ovarian reserve. However, the results were controversial. The Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number (POSEIDON) stratification is a set of newly established criteria for low prognosis patients. The aim of this study was to examine the effectiveness of dual-trigger for final oocyte maturation on the in vitro fertilization (IVF) outcomes of patients who fulfill the POSEIDON group 4 criteria.
This retrospective cohort study investigated 384 cycles fulfilling the POSEIDON group 4 criteria. The patients underwent IVF treatment using the gonadotropin-releasing hormone (GnRH) antagonist protocol. The study group contained 194 cycles that received dual-trigger (human chorionic gonadotropin [hCG] plus GnRH-agonist) for final oocyte maturation. The control group included 114 cycles where final oocyte maturation was performed with only hCG. Baseline characteristics and cycle parameters, as well as IVF outcomes of both groups were compared.
Baseline characteristics were similar between the dual trigger group and the control group. In terms of IVF outcomes, the dual trigger group demonstrated significantly higher number of retrieved oocytes, metaphase II oocytes, fertilized oocytes, day-3 embryos, and top-quality day-3 embryos. A statistically significant improvement in clinical pregnancy rate and live birth rate was also observed in the dual trigger group.
Citation: Chern C-U, Li J-Y, Tsui K-H, Wang P-H, Wen Z-H, Lin L-T (2020) Dual-trigger improves the outcomes of in vitro fertilization cycles in older patients with diminished ovarian reserve: A retrospective cohort study. PLoS ONE 15(7): e0235707. https://doi.org/10.1371/journal.pone.0235707
Editor: Simone Garzon, Universita degli Studi dell’Insubria, ITALY
Received: March 9, 2020; Accepted: June 19, 2020; Published: July 6, 2020
Copyright: © 2020 Chern et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the manuscript and its Supporting Information files.
Funding: The author received no specific funding for this work.
Competing interests: The authors have declared that no competing interests exist.
The process of in vitro fertilization (IVF) involves hyperstimulation of ovaries with gonadotropins to mimic the natural cycle in producing mature oocytes. In the normal menstrual cycle, oocyte maturation occurs following the luteinizing hormone (LH) and smaller follicle stimulating hormone (FSH) surge that happens during mid-cycle. Traditionally, human chorionic gonadotropin (hCG) has been the trigger of choice for oocyte maturation due to its molecular and biological similarity with LH . However, its half-life is much longer than LH, lasting for approximately days . This contributes to the occurrence of ovarian hyperstimulation syndrome (OHSS) in high responders. Also, hCG lacks FSH activity, which plays a role in the in vitro maturation of oocytes .
Gonadotropin-releasing hormone (GnRH) agonists were first suggested for final oocyte maturation by Gonen et al. in 1990, as it is able to trigger endogenous release of both FSH and LH . With a shorter mean duration of LH surge of about 34 hours, it is similar to the natural cycle duration of 48 hours , effectively reducing the incidence of OHSS in high responders [6, 7]. However, some problems surfaced with the substitution of GnRH-agonists as trigger. Kummer et al. discovered that the risk of empty follicle syndrome was increased following isolated GnRH-agonist trigger due to a suboptimal LH surge . Additionally, increased early pregnancy loss and decreased rates of ongoing pregnancy were noted by multiple studies [9, 10]. As such, the idea of a dual trigger was developed . Indeed, the hCG component of dual trigger could serve as a rescue trigger in case of poor response to GnRH-agonist, which occurs in about 2.71% of a study population .
Since its development, multiple investigations have shown the benefits of using a dual trigger for final oocyte maturation in normal responders [11, 13], including an improvement in total number of retrieved oocytes, MII oocytes, rates of embryo implantation, clinical pregnancy, and live birth rates . Evidence from available meta-analysis in 2018 involving four studies including 527 patients found a significantly improved clinical pregnancy rate following dual trigger . However, for poor ovarian responders (PORs), the situation is less clear cut.
Women with poor ovarian response are those who have a reduced number of follicles responsive to FSH, resulting in poor IVF outcomes –posing a grave challenge to clinicians worldwide. Numerous criteria have been proposed for the definition of POR , but none was established as the international standard to define POR until the creation of the Bologna criteria in 2011 . Presence of much heterogeneity lead to strong criticism about the clinical application of the Bologna criteria , triggering the development of the POSEIDON (Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number) criteria in 2016 . The POSEIDON criteria brings forward the concept of “low prognosis”, and classifies all patients according to 3 factors: oocyte quality as demonstrated by age, oocyte quantity as represented by ovarian biomarkers of anti-Müllerian hormone (AMH) and/or antral follicle count (AFC), and finally ovarian response, dependent on the number of oocytes retrieved given a previous ovarian stimulation cycle. As such, it is able to aid the clinician in formulating a more tailored treatment plan for the individual groups. The focus of our study is POSEIDON group 4, with patients who are ≥ 35 years old, with AFC < 5 and/or AMH < 1.2 ng/mL. However, it is of note that the patients in POSEIDON group 4 do not display elevated FSH, which is a distinguishing feature of premature ovarian insufficiency.
Based on the existing evidence of improved reproductive outcomes in normal responders, and the theoretical advantage of a more physiologic trigger while reducing risk of poor response to GnRH-agonist alone, we hypothesized that similar benefits can be obtained using dual-trigger in a low prognosis group like POSEIDON 4. Therefore, we attempted to investigate the feasibility of utilizing dual-trigger for final oocyte maturation in improving IVF outcomes of this population.
Materials and methods
Study design and participants
The retrospective cohort study was performed at the reproductive medical center of Kaohsiung Veterans General Hospital, in Kaohsiung, Taiwan from January 2012 through December 2017. The study protocol was approved by the institutional review board at Kaohsiung Veterans General Hospital, with the identifier VGHKS19-CT8-05, and conforms to the “Declaration of Helsinki for Medical Research involving Human Subjects.” The need for consent was waived by the ethics committee due to its retrospective design. Data was compiled from electronic medical records and cycle flow sheets for patients within the study period. Patients who underwent IVF cycles and fulfilled the criteria for POSEIDON group 4 (age ≥ 35 years, with AFC < 5 and/or AMH < 1.2 ng/mL) were included in this study. IVF is the treatment of choice for this group of patients characterized by advanced maternal age and low ovarian reserve due to its relatively higher success rate compared to other treatment modalities. A total of 384 cycles met the criteria during the study period. Exclusion criteria were as follows: (i) Patients who did not receive GnRH antagonist protocol, (ii) patients with premature ovarian insufficiency, (iii) patients over the age of 45, (iv) cancer patients who have received chemotherapy or radiotherapy, and (v) patients with incomplete data. Following application of the exclusion criteria, a total of 308 cycles were included for study and then divided into dual-trigger and hCG trigger groups. The choice of hCG alone or dual-trigger depended on the physician, with cycles before 2015 being mostly hCG-only trigger and those after 2015 being mostly dual-trigger. In the dual-trigger group (n = 194), patients received final oocyte maturation with GnRH-agonist and hCG. In the hCG trigger group (n = 114), patients received only hCG for final oocyte maturation.
Only patients receiving GnRH antagonist protocol were included in this study. Following a baseline hormone screen and transvaginal ultrasound for antral follicles, controlled ovarian stimulation was initiated within 5 days of the menstrual cycle, with recombinant follicle stimulating hormone (rFSH, Gonal-F, Merck Serono S.p.A., Modugno, Italy), rFSH plus recombinant luteinizing hormone (Pergoveris, Merck Serono SA, Aubonne, Switzerland), human menopausal gonadotropin (Merional, IBSA Institut Biochimique S.A., Lamone, Switzerland), or corifollitropin alfa (Elonva, Vetter Pharma-Fertigung GmbH & Co, KG, Ravensburg, Germany). Furthermore, addition of growth hormone (Saizen, Merck Serono SA, Aubonne, Switzerland) was given during controlled ovarian stimulation at physician’s discretion.
Patient response was monitored during the IVF cycle with serial transvaginal ultrasound for follicular measurements and hormone profiles. Dosage was adjusted depending on follicular response and previous response to gonadotropins. Daily GnRH antagonist injections (Cetrotide 0.25mg, Pierre Fabre Medicament Production, Aquitaine Pharm International, Idron, France or Orgalutran 0.25mg, Vetter Pharma-Fertigung GmbH & Co, KG, Ravensburg, Germany) were administered when the leading follicle reaches 12–14 mm in diameter, up till the date of final oocyte maturation. Patient then either received dual-trigger with combined recombinant hCG (Ovidrel 250μg, Merck Serono S.p.A., Modugno, Italy) with GnRH agonist (Lupro 2mg, Nang Kuang Pharmaceutical Co, Ltd., Tainan, Taiwan) or recombinant hCG alone. Trigger is given when at least one leading follicle reaches a mean diameter of 18 mm.
Transvaginal ultrasound-guided oocyte retrieval was performed 36 h following administration of trigger. Whether fertilization was conducted by conventional IVF or intracytoplasmic sperm injection (ICSI) depended on semen analysis results or prior fertilization condition. Embryos were evaluated and graded according to the criteria established by the Istanbul consensus workshop . The number of blastomeres, the percentage of fragmentation and the variation in blastomere symmetry were assessed. Top-quality cleavage stage embryos were determined as those with the following features: six cells or greater on day 3, less than 10% fragmentation and symmetric blastomeres. All embryos were cryopreserved by vitrification under a freeze-all strategy on the third day after oocyte retrieval for subsequent frozen embryo transfer. As such, no embryo qualified for preimplantation genetic testing for aneuploidies (PGT-A). Vitrification was carried out via a two-step exposure to equilibrium and vitrification solutions. The embryo is first exposed to the equilibrium solution for 15 minutes, followed by exposure to the vitrification solution for 1 minute and 30 seconds. The embryo is then loaded onto the propylene strip of Cryotop (Kitazato, Bio Pharma Co., Tokyo, Japan) in an open system with minimal solution, and then rapidly plunged into liquid nitrogen at -196°C. An artificial cycle was used for endometrial preparation. Endometrium was prepared with daily oral estradiol (Ediol 8mg, Synmosa Biopharma Corporation, Hsinchu County, Taiwan) and estradiol gel (Oestrogel gel, Besins, Drogenbos, Belgium) beginning before cycle day 5.
When the endometrial thickness reaches at least 8mm, daily progesterone, including intravaginal gel (Crinone 8% gel, Merck Serono, Hertfordshire, UK) and oral dydrogesterone (Duphaston 40mg, Abbott, Olst, the Netherlands), were given simultaneously as luteal phase support. Additionally, aspirin (ASPIRIN PROTECT 100mg, Bayer AG, Leverkusen, Germany) was also prescribed routinely. Following assisted-hatching via laser zona drilling, the frozen-thawed embryos were transferred under transabdominal sonographic assistance. Progesterone supplementation was administered until 8–10 gestational weeks upon confirmation of pregnancy.
The primary outcome measure was live birth rate, defined as the delivery of a viable fetus beyond 24 weeks of gestation. Secondary outcome measures included the number of retrieved oocytes, number of mature oocytes, number of fertilized oocytes, number of day-3 embryos, number of top-quality day-3 embryos, implantation rate (calculated from the number of gestation sacs with fetal heart seen on ultrasound scan divided by the total number of transferred embryos), cancellation rate, miscarriage rate, and clinical pregnancy rate. Cancellation rate was defined as those with no retrieved oocytes, or no viable embryos, while miscarriage rate refers to pregnancy loss before 24 weeks of gestation, and clinical pregnancy rate was defined by the presence of a fetal heartbeat at 6–7 weeks of a pregnancy.
Kolmogovor-Smirnov test was used to evaluate normality of quantitative variables. Quantitative variables were evaluated using the independent t-test. Chi-Square test was used to evaluate categorical variables. Odds ratios (ORs) and 95% confidence intervals (CIs) of live birth and clinical pregnancy were assessed using generalized estimating equations (GEEs), after adjusting for confounders. We adopted GEEs to account for correlations between multiple cycles from the same patient. Key factors including age, BMI, infertility duration, previous IVF attempts, basal FSH, AFC, AMH, number of pre-ovulatory follicles > 10 mm on trigger day, and number of pre-ovulatory follicles > 14 mm on trigger day, were identified as confounders for analyses. Analyses were performed using the Statistical Package for Social Sciences (SPSS) version 20.0 (Chicago, IL, USA). P < 0.05 was considered statistically significant.
As shown in Fig 1, out of 2,165 IVF cycles, 384 cycles fulfilled the POSEIDON group 4 criteria. Of the 384 cycles, 38 were not treated using a GnRH antagonist protocol, 8 were diagnosed with premature ovarian insufficiency, 19 with advanced maternal age of more than 45 years old, 3 were cancer patients who underwent chemotherapy and/or radiotherapy, and 8 had incomplete dataset. Those cycles were excluded from the study. Of the remaining 194 cycles in the dual-trigger group and 114 in the hCG-only trigger group, a further 34 cycles were excluded in the dual-trigger group, and 22 cycles excluded in the hCG-only group due to no retrieved oocytes or no viable embryos. As such, 160 frozen-thawed embryo transfer cycles from the dual-trigger group and 92 frozen-thawed embryo transfer cycles from the hCG-only group were available for analysis.
IVF, in vitro fertilization; ICSI, intracytoplasmic sperm injection; GnRH, gonadotropin-releasing hormone; POI, primary ovarian insufficiency; FET, frozen embryo transfer.
Comparisons between the populations of two groups revealed no difference in patient age, body mass index, infertility duration, previous IVF attempts, primary or secondary infertility, cause of infertility, basal FSH, basal luteinizing hormone (LH), basal estradiol (E2), AFC and AMH (Table 1).
Cycle characteristics between the two groups are presented in Table 2. There were no differences in terms of stimulation duration, types of gonadotropins, total gonadotropin dose and percentage of growth hormone supplementation. Pre-ovulatory follicles > 10 mm (3.7±2.6 vs. 3.4±1.5, p = 0.573) and pre-ovulatory follicles > 14 mm (2.9±2.2 vs. 2.7±0.9, p = 0.191) on trigger day were similar between the two groups. However, the number of retrieved oocytes (3.3±2.7 vs. 1.6±1.5, p<0.001), metaphase II oocytes (2.6±2.0 vs. 1.3±1.0, p<0.001), fertilized oocytes (2.4±2.1 vs. 1.2±1.0, p<0.001), day-3 embryos (2.2±1.9 vs. 1.2±1.0, p< 0.001) and top-quality day-3 embryos (0.9±1.3 vs. 0.2±0.5, p<0.001) were significantly higher in the dual-trigger group compared with the hCG-only group. Moreover, methods of fertilization, fertilization rate and cancellation rate were similar between the two groups.
Pregnancy outcomes between the two groups are presented in Table 3. Endometrium thickness was similar between the two groups. However, the number of transferred embryos (2.1±1.0 vs. 1.4±0.8, p<0.001) and percentage of at least one top-quality embryos transfer (62.5% vs. 23.9%, p<0.001) were significantly higher in the dual-trigger group than in the hCG-only group. Of note, the dual-trigger group performed superiorly in terms of implantation rate (14.4±30.0% vs. 5.4±18.8%, p = 0.004), clinical pregnancy rate (23.1% vs. 8.7%, p = 0.004) and live birth rate (17.5% vs. 5.4%, p = 0.006). Furthermore, there was no significant difference in miscarriage rate between the two groups.
GEEs were performed to determine whether dual-trigger use had a beneficial effect on clinical pregnancy rate and live birth rate in Table 4. Confounding variables such as age, BMI, duration of infertility, previous IVF attempts, basal FSH, AFC, AMH, number of pre-ovulatory follicles > 10 mm on trigger day, and number of pre-ovulatory follicles > 14 mm on trigger day were included in the analysis. The analysis showed that dual-trigger use was positively associated with live birth rate (OR = 3.16, 95% CI 1.06–9.38, p = 0.039) and clinical pregnancy rate (OR = 4.30, 95% CI 1.38–13.43, p = 0.012). Furthermore, AMH was shown to be a positive independent factor affecting clinical pregnancy rate (OR = 7.20, 95% CI 1.31–39.61, p = 0.023).
This retrospective cohort study is the first to assess the effects of dual-trigger on IVF outcomes in patients fulfilling the POSEIDON group 4 criteria. Our study showed that dual-trigger is superior to hCG administration alone for final oocyte maturation in producing increased numbers of retrieved oocytes, metaphase II oocytes, fertilized oocytes, day-3 embryos and top-quality day-3 embryos. Clinical pregnancy rate and live birth rate were also improved with dual-trigger administration. Moreover, the analysis using GEEs revealed a 4.30-fold increase in clinical pregnancy (95% CI 1.38–13.43, p = 0.012) and a 3.16-fold increase in live birth (95% CI 1.06–9.38, p = 0.039) in the POSEIDON group 4 patients with dual trigger compared to those using hCG trigger alone. Similar outcomes have been obtained in the study of patients with diminished ovarian reserve or poor ovarian reserve in recent years, showing a beneficial effect of dual-trigger in improving IVF outcomes. Lin et al. confirmed in a recent retrospective cohort study involving 427 GnRH antagonist IVF cycles with fresh embryo transfer that dual-triggering significantly increases the live birth rate (26.9% vs 14.5%, p = 0.014), clinical pregnancy rate (33.0% vs. 20.7%, p = 0.035), and fertilization rate (73.1% vs. 58.6%, p = 0.015) in women with diminished ovarian reserve, compared to hCG-alone trigger . In an even larger retrospective cohort study with 1389 IVF cycles fulfilling the Bologna criteria, utilizing the progesterone-primed ovarian stimulation protocol, Zhang et al. also reports significantly higher number of oocytes collected (p < 0.001) with improved number of mature oocytes (p < 0.001) . However, other studies have found dual-trigger to be ineffective at improving IVF outcomes for this population. Eser et al., in a case control study involving 47 dual-trigger and 62 hCG-only trigger cases fulfilling the Bologna criteria for POR, discovered no statistical difference between the two groups with reference to implantation rate, biochemical pregnancy rate, clinical pregnancy rate, and ongoing pregnancy rate . Due to the divergence of opinion on the effectiveness and clinical utility of dual-trigger for final oocyte maturation, large-scale randomized controlled trials are required to reach a verdict.
In combining GnRH-agonist and hCG for the final oocyte trigger, we are in essence enjoying the best of both worlds. Despite being molecularly similar, hCG and LH elicit different gene expressions. LH tends towards cellular growth, which supports embryo development and survival, whereas hCG enhances apoptosis [25, 26]. hCG administration alone also does not produce FSH activity, while GnRH-agonist releases an endogenous FSH and LH surge, resulting in a more physiologic response.
In vitro studies have highlighted the role of FSH in oocyte maturation , via the increased production of epiregulin (Ereg) and amphiregulin (Areg) , members of the epidermal growth factor-like (EGF) family, which have been shown to mediate the LH signal and participate in cumulus expansion and oocyte maturation . This has been confirmed in vitro experiments, where Ereg and Areg presence in maturation medium helps to improve the maturation rate of human GV oocytes . Animal studies have also shown that FSH has the independent ability of inducing ovulation , perhaps by stimulating plasminogen activator activity, which converts plasminogen into active protease plasmin, helping to weaken the follicular wall and aiding rupture and oocyte dissociation [3, 31, 32]. Also, the FSH surge induces LH formation on luteinized granulosa cells, promoting oocyte maturation and cumulus expansion .
Additionally, direct GnRH receptor activation as identified by Raga et al. could also have an effect on preimplantation embryonic development that is unrelated to FSH activity . The GnRH receptor expression was found to be greatest in granulosa cells , and in rat models, administration of GnRH-agonists induced an increase in receptor levels in a dose-dependent manner, whereas LH decreased GnRH receptor mRNA levels . Administration of GnRH-agonist trigger has also demonstrated the retrieval of more MII oocytes (16%) . As such, the triggering cocktail of hCG, FSH, LH and GnRH-agonist serves to provide the benefits of a multi-faceted approach.
Subgroups include those with low proportion of mature oocytes (< 66%) per number of oocytes retrieved , where it was demonstrated that patients who received dual-trigger had significantly higher number of MII oocytes (6.5 vs. 3.6, p< 0.008), number of oocytes retrieved (69.7% vs. 47.1%, p < 0.03), and a higher number of top-quality embryos (3.1 vs. 1, p < 0.02) . Moreover, those with history of poor fertilization, as defined by fertilization rate < 20% in at least two prior ICSI cycle, are also a potential benefit of such a combination. In their retrospective cohort study, Elias et al. found in 2017 that the mean fertilization rate in the combined trigger group was found to be significantly higher 16.4% (95% CI 7.58%–25.2%), with higher oocyte maturity (82.1% vs. 69.8%), higher clinical pregnancy (27.5% vs. 5.67%), and higher live birth rates (20.2% vs. 3.46%) compared to the hCG trigger group .
The relatively small sample size of this study along with its retrospective design poses major limitations. The retrospective nature of this study makes it more susceptible to selection bias. Selection of cases for dual-trigger or hCG only trigger and growth hormone use was up to the physician’s discretion, predisposing it to possibility of bias. Also, as most of the cases utilized dual-trigger following 2015, while those prior to 2015 utilized hCG-only trigger, we cannot rule out the effects of chronological bias. Another shortcoming of our study is that although all cycles were antagonist cycles with similar types of gonadotropins between both groups, using various types of gonadotropins still leads to possibility of bias. The strength of our study is that all clinical decisions and oocyte pick-ups were performed by the same physician, leading to less variability in performance.
Our data suggest that dual trigger might increase both oocyte and embryo yields, as well as clinical pregnancy rates and live birth rates in patients fulfilling the POSEIDON group 4 criteria. However, large-scale randomized controlled studies are needed to confirm these findings.
- 1. Ascoli M, Fanelli F, Segaloff DL. The lutropin/choriogonadotropin receptor, a 2002 perspective. Endocr Rev. 2002;23(2):141–74. Epub 2002/04/12. pmid:11943741.
- 2. Gonen Y, Balakier H., Powell W., Casper R.F. Use of gonadotropin-releasing hormone agonist to trigger follicular maturation for in vitro fertilization. J Clin Endocrinol Metab. 1990;71(4):918–22. pmid:2119392
- 3. Strickland S, Beers WH. Studies on the role of plasminogen activator in ovulation. In vitro response of granulosa cells to gonadotropins, cyclic nucleotides, and prostaglandins. J Biol Chem. 1976;251(18):5694–702. Epub 1976/09/25. pmid:965386.
- 4. Humaidan P, Bungum M, Bungum L, Yding Andersen C. Effects of recombinant LH supplementation in women undergoing assisted reproduction with GnRH agonist down-regulation and stimulation with recombinant FSH: an opening study. Reprod Biomed Online. 2004;8(6):635–43. Epub 2004/06/01. pmid:15169576.
- 5. Hoff JD. Q M, Yen SS. Hormonal dynamics at midcycle: a reevaluation. J Clin Endocrinol Metab. 1983;57(4):792–6. pmid:6411753
- 6. Engmann L, DiLuigi A, Schmidt D, Nulsen J, Maier D, Benadiva C. The use of gonadotropin-releasing hormone (GnRH) agonist to induce oocyte maturation after cotreatment with GnRH antagonist in high-risk patients undergoing in vitro fertilization prevents the risk of ovarian hyperstimulation syndrome: a prospective randomized controlled study. Fertil Steril. 2008;89(1):84–91. Epub 2007/04/28. pmid:17462639.
- 7. Griesinger G, von Otte S, Schroer A, Ludwig AK, Diedrich K, Al-Hasani S, et al. Elective cryopreservation of all pronuclear oocytes after GnRH agonist triggering of final oocyte maturation in patients at risk of developing OHSS: a prospective, observational proof-of-concept study. Hum Reprod. 2007;22(5):1348–52. Epub 2007/02/17. pmid:17303632.
- 8. Kummer NE, Feinn RS, Griffin DW, Nulsen JC, Benadiva CA, Engmann LL. Predicting successful induction of oocyte maturation after gonadotropin-releasing hormone agonist (GnRHa) trigger. Hum Reprod. 2013;28(1):152–9. Epub 2012/10/19. pmid:23077235.
- 9. Humaidan P, Bredkjaer HE, Bungum L, Bungum M, Grondahl ML, Westergaard L, et al. GnRH agonist (buserelin) or hCG for ovulation induction in GnRH antagonist IVF/ICSI cycles: a prospective randomized study. Hum Reprod. 2005;20(5):1213–20. Epub 2005/03/12. pmid:15760966.
- 10. Kolibianakis EM, Schultze-Mosgau A, Schroer A, van Steirteghem A, Devroey P, Diedrich K, et al. A lower ongoing pregnancy rate can be expected when GnRH agonist is used for triggering final oocyte maturation instead of HCG in patients undergoing IVF with GnRH antagonists. Hum Reprod. 2005;20(10):2887–92. Epub 2005/06/28. pmid:15979994.
- 11. Shapiro BS, Daneshmand ST, Garner FC, Aguirre M, Thomas S. Gonadotropin-releasing hormone agonist combined with a reduced dose of human chorionic gonadotropin for final oocyte maturation in fresh autologous cycles of in vitro fertilization. Fertil Steril. 2008;90(1):231–3. Epub 2007/11/06. pmid:17981269.
- 12. Lu X, Hong Q, Sun L, Chen Q, Fu Y, Ai A, et al. Dual trigger for final oocyte maturation improves the oocyte retrieval rate of suboptimal responders to gonadotropin-releasing hormone agonist. Fertil Steril. 2016;106(6):1356–62. Epub 2016/08/05. pmid:27490046.
- 13. Shapiro BS, Daneshmand ST, Garner FC, Aguirre M, Hudson C. Comparison of "triggers" using leuprolide acetate alone or in combination with low-dose human chorionic gonadotropin. Fertil Steril. 2011;95(8):2715–7. Epub 2011/05/10. pmid:21550042.
- 14. Lin MH, Wu FS, Lee RK, Li SH, Lin SY, Hwu YM. Dual trigger with combination of gonadotropin-releasing hormone agonist and human chorionic gonadotropin significantly improves the live-birth rate for normal responders in GnRH-antagonist cycles. Fertil Steril. 2013;100(5):1296–302. Epub 2013/09/03. pmid:23993928.
- 15. Chen CH, Tzeng CR, Wang PH, Liu WM, Chang HY, Chen HH, et al. Dual triggering with GnRH agonist plus hCG versus triggering with hCG alone for IVF/ICSI outcome in GnRH antagonist cycles: a systematic review and meta-analysis. Arch Gynecol Obstet. 2018;298(1):17–26. Epub 2018/03/31. pmid:29600322.
- 16. Esteves SC, Roque M, Bedoschi GM, Conforti A, Humaidan P, Alviggi C. Defining Low Prognosis Patients Undergoing Assisted Reproductive Technology: POSEIDON Criteria-The Why. Front Endocrinol (Lausanne). 2018;9:461. Epub 2018/09/04. pmid:30174650
- 17. Polyzos NP, Devroey P. A systematic review of randomized trials for the treatment of poor ovarian responders: is there any light at the end of the tunnel? Fertil Steril. 2011;96(5):1058–61.e7. Epub 2011/11/01. pmid:22036048.
- 18. Ferraretti AP, La Marca A, Fauser BC, Tarlatzis B, Nargund G, Gianaroli L. ESHRE consensus on the definition of ‘poor response’ to ovarian stimulation for in vitro fertilization: the Bologna criteria. Hum Reprod. 2011;26(7):1616–24. Epub 2011/04/21. pmid:21505041.
- 19. Younis JS, Ben-Ami M, Ben-Shlomo I. The Bologna criteria for poor ovarian response: a contemporary critical appraisal. J Ovarian Res. 2015;8:76. Epub 2015/11/19. pmid:26577149
- 20. Humaidan P, Alviggi C, Fischer R, Esteves SC. The novel POSEIDON stratification of ‘Low prognosis patients in Assisted Reproductive Technology’ and its proposed marker of successful outcome. F1000Res. 2016;5:2911. Epub 2017/02/25. pmid:28232864
- 21. Medicine ASiR Embryology ESIGo. The Istanbul consensus workshop on embryo assessment: proceedings of an expert meeting†. Human Reproduction. 2011;26(6):1270–83. pmid:21502182
- 22. Lin MH, Wu FS, Hwu YM, Lee RK, Li RS, Li SH. Dual trigger with gonadotropin releasing hormone agonist and human chorionic gonadotropin significantly improves live birth rate for women with diminished ovarian reserve. Reprod Biol Endocrinol. 2019;17(1):7. Epub 2019/01/06. pmid:30609935
- 23. Zhang J, Wang Y, Mao X, Chen Q, Hong Q, Cai R, et al. Dual trigger of final oocyte maturation in poor ovarian responders undergoing IVF/ICSI cycles. Reprod Biomed Online. 2017;35(6):701–7. Epub 2017/10/11. pmid:28993105.
- 24. Eser A, Devranoglu B, Bostanci Ergen E, Yayla Abide C. Dual trigger with gonadotropin-releasing hormone and human chorionic gonadotropin for poor responders. J Turk Ger Gynecol Assoc. 2018;19(2):98–103. Epub 2018/03/09. pmid:29516855
- 25. Grondahl ML, Borup R, Lee YB, Myrhoj V, Meinertz H, Sorensen S. Differences in gene expression of granulosa cells from women undergoing controlled ovarian hyperstimulation with either recombinant follicle-stimulating hormone or highly purified human menopausal gonadotropin. Fertil Steril. 2009;91(5):1820–30. Epub 2008/04/29. pmid:18439596.
- 26. Ruvolo G, Bosco L, Pane A, Morici G, Cittadini E, Roccheri MC. Lower apoptosis rate in human cumulus cells after administration of recombinant luteinizing hormone to women undergoing ovarian stimulation for in vitro fertilization procedures. Fertil Steril. 2007;87(3):542–6. Epub 2006/11/28. pmid:17126339.
- 27. Haas J, Ophir L, Barzilay E, Machtinger R, Yung Y, Orvieto R, et al. Standard human chorionic gonadotropin versus double trigger for final oocyte maturation results in different granulosa cells gene expressions: a pilot study. Fertil Steril. 2016;106(3):653–9 e1. Epub 2016/06/28. pmid:27341989.
- 28. Park J, Su Y, Ariga M, Law E, Jin S, Conti M. EGF-like growth factors as mediators of LH action in the ovulatory follicle. Science. 2004;303:682–4. pmid:14726596
- 29. Ben-Ami I, Komsky A, Bern O, Kasterstein E, Komarovsky D, Ron-El R. In vitro maturation of human germinal vesicle-stage oocytes: role of epidermal growth factor-like growth factors in the culture medium. Hum Reprod. 2011;26(1):76–81. Epub 2010/10/22. pmid:20961941.
- 30. Zelinksi-Wooten MB, Hutchison J.S., Wolf D.P., Stouffer R.L. A bolus of recombinant human follicle stimulating hormone at midcycle induces periovulatory events following multiple follicular development in macaques. Hum Reprod. 1998;13(3):554–60. pmid:9572409
- 31. Morioka N, Zhu C, Brannstrom M, Woessner JF, LeMaire WJ. Mechanism of mammalian ovulation. Prog Clin Biol Res. 1989;294:65–85. Epub 1989/01/01. pmid:2657783.
- 32. Lamb JD, Shen S, McCulloch C, Jalalian L, Cedars MI, Rosen MP. Follicle-stimulating hormone administered at the time of human chorionic gonadotropin trigger improves oocyte developmental competence in in vitro fertilization cycles: a randomized, double-blind, placebo-controlled trial. Fertil Steril. 2011;95(5):1655–60. Epub 2011/02/15. pmid:21315341.
- 33. Humaidan P, Kol S, Papanikolaou EG, Copenhagen Gn RHATWG. GnRH agonist for triggering of final oocyte maturation: time for a change of practice? Hum Reprod Update. 2011;17(4):510–24. Epub 2011/04/01. pmid:21450755.
- 34. Raga F, Bonilla-Musoles F, Casan EM, Bonilla F. Recombinant follicle stimulating hormone stimulation in poor responders with normal basal concentrations of follicle stimulating hormone and oestradiol: improved reproductive outcome. Hum Reprod. 1999;14(6):1431–4. Epub 1999/06/08. pmid:10357953.
- 35. Bauer-Dantoin AC, Weiss J, Jameson JL. Roles of estrogen, progesterone, and gonadotropin-releasing hormone (GnRH) in the control of pituitary GnRH receptor gene expression at the time of the preovulatory gonadotropin surges. Endocrinology. 1995;136(3):1014–9. Epub 1995/03/01. pmid:7867555.
- 36. Limonta P, Moretti RM, Montagnani Marelli M, Motta M. The biology of gonadotropin hormone-releasing hormone: role in the control of tumor growth and progression in humans. Front Neuroendocrinol. 2003;24(4):279–95. Epub 2004/01/17. pmid:14726258.
- 37. Griffin D, Feinn R, Engmann L, Nulsen J, Budinetz T, Benadiva C. Dual trigger with gonadotropin-releasing hormone agonist and standard dose human chorionic gonadotropin to improve oocyte maturity rates. Fertil Steril. 2014;102(2):405–9. Epub 2014/05/21. pmid:24842671.
- 38. Zilberberg E, Haas J, Dar S, Kedem A, Machtinger R, Orvieto R. Co-administration of GnRH-agonist and hCG, for final oocyte maturation (double trigger), in patients with low proportion of mature oocytes. Gynecol Endocrinol. 2015;31(2):145–7. Epub 2014/11/12. pmid:25385007.
- 39. Elias RT, Pereira N, Artusa L, Kelly AG, Pasternak M, Lekovich JP, et al. Combined GnRH-agonist and human chorionic gonadotropin trigger improves ICSI cycle outcomes in patients with history of poor fertilization. J Assist Reprod Genet. 2017;34(6):781–8. Epub 2017/04/27. pmid:28444614