Hormone levels were measured with chemiluminescence Abbott Biologicals B. Intra- and inter-assay coefficients of variation were 2. Premature ovulation was defined as the dominant follicle rupture before the scheduled time. Elevated progesterone alone was not defined as the presentation of LH surge and was listed independently.
Secondary efficacy parameters included the number of oocytes and viable embryos, the clinical pregnancy rate, implantation rate and live birth rate. Clinical pregnancy was defined as the presence of intrauterine gestation sac at 7 weeks of gestation. Live birth was defined as the delivery of an infant after 28 weeks of gestation. The safety endpoints included the incidence of ovarian hyperstimulation syndrome OHSS , miscarriage, ectopic pregnancy and pregnancy complications.
For the power calculation, previous studies reported that the incidence of premature LH surge in GnRH antagonist protocol was 8. The superiority margin was set as 4. Given the abundant clinical resources in our clinic, the number of participants was set as in each group in this trial. We utilized an intention-to-treat approach ITT to examine differences of the primary endpoint the incidence of premature LH surge and secondary endpoints.
The difference between the incidence of premature LH surge for the two groups was tested via two-sided Chi-square test for independence. An exploratory analysis of transition probabilities for outcomes was also conducted to evaluate potential differences between treatment arms.
Adverse events were monitored and recorded throughout the trial. The full analysis and per protocol analysis were also executed in this trial and used as a complement. A flowchart of the participant allocation is presented in Figure 1. A total of 1, women underwent screening, and met the eligibility criteria. Of these women, 31 discontinued to treatment and quitted for other reasons.
Characteristics of participants, by treatment arm, are shown in Table 1. A total of 19 of patients Four women in the GnRH antagonist group did not prescribe antagonist due to the short follicular phase, their follicles reached the mature criteria after 5—6 days' stimulation of gonadotropin, then arranged for oocyte retrieval.
One case in PPOS group ovulated due to the accidentally delay of retrieval at A total of 24 cases 11 in antagonist group and 13 cases in PPOS group did not continue to transfer their cryopreserved embryos. GnRH antagonist group showed a wider spread of LH values on the trigger day ranged from 0. Figure 2. Additionally, 2 cases in antagonist group unexpectedly ovulated at 36 h after trigger before oocyte retrieval although they did not show signs of premature LH rise.
Another case presented elevated progesterone alone without LH rise or dominant follicle rupture in GnRH antagonist group and it was listed separately. These data showed the context of pituitary suppression using GnRH antagonist was more variable compared to that of PPOS in poor responders.
The GnRH antagonist dose and duration were 0. The MPA duration was 8. The average E 2 value on the trigger day was comparable between the two groups Table 2. A total of cases completed oocyte retrieval and cases successfully harvested at least one oocyte. The numbers of retrieved oocytes were 3.
The numbers of viable embryos used for transfer were comparable between the two groups 1. The proportions of viable embryos per retrieved oocyte were similar between the two groups Of 10 cases with LH surge in GnRH antagonist group, 3 cases with typical LH surge did not use trigger and harvested at least one mature oocyte on the next day, the other 7 cases were retrieved in advance based on the impending sign of ovulation, resulting into 6 cases with at least one mature oocyte.
Three of the 10 cases produced at least one viable embryo and resulted into two live births. Hundred and nineteen cases in the GnRH antagonist group obtained at least one viable embryo and 83 cases completed a fresh embryo transfer, resulting into 26 clinical pregnancies.
A total of transfer cycles had completed up to September The miscarriage rate was comparable in all pregnancies of both groups One case of ectopic pregnancy occurred in the PPOS group. Table 3. Follicular atresia and infertility in rats treated with a gonadotropin-releasing hormone antagonist. Endocrinology , 25—31, doi: A quantitative analysis of the physiological role of estradiol and progesterone in the control of tonic and surge secretion of luteinizing hormone in the rat.
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Download references. You can also search for this author in PubMed Google Scholar. All the authors reviewed the manuscript. Correspondence to Yanping Kuang or Kevin T. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Reprints and Permissions. He, W. Hypothalamic effects of progesterone on regulation of the pulsatile and surge release of luteinising hormone in female rats. Sci Rep 7, Download citation. Received : 05 May Accepted : 12 July Published : 14 August Anyone you share the following link with will be able to read this content:.
Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Epub Apr 9. Epub Aug 9. Effects of oral contraceptive, synthetic progestogen or natural estrogen pre-treatments on the hormonal profile and the antral follicle cohort before GnRH antagonist protocol.
Epub Aug The pregnancy outcome of progestin-primed ovarian stimulation using 4 versus 10 mg of medroxyprogesterone acetate per day in infertile women undergoing in vitro fertilisation: a randomised controlled trial.
National Library of Medicine U. National Institutes of Health U. Department of Health and Human Services. The safety and scientific validity of this study is the responsibility of the study sponsor and investigators.
Drug: GnRh antagonist Drug: Micronized progesterone. Not Applicable. Study Type :. Interventional Clinical Trial. Estimated Enrollment :. Actual Study Start Date :. Estimated Primary Completion Date :. Estimated Study Completion Date :.
Experimental: Micronized progesterone In the progesterone cycle, endogenous LH suppression will be accomplished by oral administration of micronized progesterone mg once a day at bed time, from stimulation day 1 and continuing until ovulation triggering. Other Name: Utrogestan.
Contact: Ignacio Rodriguez, msc ext nacrod dexeus. September 27, Key Record Dates. No LH surges were seen in negative controls 0 out of 7 ewes.
Although the onset of the surge in progesterone-treated ewes appeared to be delayed relative to positive control ewes Table 2 and Fig. Summary of the results of experiment 2. The results of this study provide novel information about the mechanisms by which progesterone and estradiol interact to regulate expression of the preovulatory surges of GnRH and LH. Furthermore, the results demonstrate that the disruptive effects of progesterone during activation are transient, because exposure to progesterone during activation does not compromise the ability of animals to respond to subsequent estradiol exposure.
The development of a model system in which it is possible to dissect the GnRH surge induction process into its 3 constituent stages activation, transmission, and hormone release , has provided a means to investigate the interaction between estradiol and progesterone in regulating expression of the surge.
The information obtained about the temporal sequence of steroid actions is of interest when the sequence of neuronal events that must occur to generate a GnRH surge are considered. For instance, Harris et al. This indicated that progesterone could act either to prevent the transfer of information between estradiol-responsive neuronal systems involved in surge generation and GnRH neurons or by altering the activity of neurons that are influenced by an estradiol-responsive GnRH-afferent system.
The results of the present study demonstrate that in addition to the effects of progesterone on transmission of the surge induction signal, progesterone is extremely effective in preventing activation of the positive feedback system by estradiol.
Indeed, the process of activation appears to be so sensitive to disruption by progesterone that exposure for only part either the first or second half of the activation stage is as effective in preventing the surge as exposure to progesterone throughout the activation stage. It should be noted that 2 of 7 ewes that were treated with progesterone early in the activation stage in experiment 1 exhibited an LH surge.
Although it could be argued that progesterone did not disrupt the activation stage in these 2 animals, an alternative explanation is that progesterone concentrations might have been below a critical level required to inhibit the activational effects of estradiol.
However, significant interindividual differences in progesterone concentrations have not been seen in ewes treated with CIDRs [ 12 , 31 — 34 ], and it is therefore more likely that the surges in these 2 animals were the result of the 2 h of estradiol exposure that followed removal of exogenous progesterone. If this were indeed the case, induction of surges in these animals would not be contrary to the contention that progesterone can disrupt activation of the surge.
This explanation is supported by the observations that some negative controls treated with a 2-h estradiol signal exhibited an LH surge, although the 2-h signal appeared to be too short to induce a surge in most negative controls.
Other studies in ewes have also found interindividual variation in sensitivity to steroids. The results of the second experiment of the present study suggest that the disruptive action of progesterone on activation is transient, because the inhibition of activation action was limited to the period of administration.
This conclusion is based on the observation that most ewes exposed to a stimulatory period of estradiol exposure that was split by a period of exposure to progesterone into 2 parts, which by themselves should not have been sufficient to stimulate a surge, were still able to respond with an LH surge. This conclusion contains important information on the mechanisms of action of both progesterone and estradiol in the surge induction process. First, it indicates that processes initiated by the 2 periods of estradiol exposure can be summated to generate a sufficient stimulus to initiate the surge induction process, suggesting that the positive feedback system may remain in an activated state for some time in the absence of estradiol.
Second, it indicates that exposure to progesterone does not ablate the processes activated by estradiol before progesterone exposure, nor does it prevent the system from responding to further estradiol exposure. These observations suggest that the disruption of activation of the positive feedback system by progesterone occurs only in the period during which progesterone is present. As discussed above, this might be explained by these ewes having a greater sensitivity to the inhibitory effects of progesterone or a lower sensitivity to the stimulatory effects of estradiol, or a combination of both.
Finally, it is possible that the disruptive effects of progesterone are stronger in the absence of estradiol, because the incidence of LH surges was lower when estradiol was removed during the progesterone treatment. This would suggest that estradiol and progesterone interact centrally in some way in determining the sensitivity of the GnRH system to activation.
It is likely that during the activation stage of the surge induction process, estradiol-estradiol receptor complexes are formed in estradiol-receptive cells. This leads to the activation of estrogen-receptive neurons, which probably involves the induction of transcription of estradiol-responsive genes.
If progesterone were to disrupt such processes through a direct action that is, an action that did not require the induction of progesterone-responsive genes , its action would be expected to be rapid, and would be manifested only when the concentrations of both estradiol and progesterone are elevated.
Alternatively, if the disruptive action required progesterone-induced gene products, it would be expected to have a relatively slower onset, but it may persist longer.
The speed and time course of the disruptive actions of progesterone observed in the present study are consistent with the former possibility; namely, that progesterone may disrupt activation by directly inhibiting estradiol-induced cellular activation.
Although we have not addressed the effects of progesterone on estradiol-responsive cells in this study, this hypothesis is supported by in vitro studies in which progesterone has been shown to prevent the transcription of estradiol-responsive genes [ 36 , 37 ]. In addition, studies of the effects of progesterone on estradiol-induced expression of the protein product of the immediate-early gene, c -fos , which is believed to be involved in the regulation of transcription in several neuronal systems [ 38 ], also support this idea.
For example, the increase in Fos expression in GnRH and non-GnRH cells that is normally observed when a GnRH surge is induced by estradiol, is absent from rats and ewes that have been treated with progesterone to prevent activation of the surge [ 39 , 40 ]. An alternative explanation of the effects noted in the present study could be that the progesterone acts at the level of the pituitary gland to prevent LH secretion despite increased GnRH secretion.
Although such an action has been shown to contribute to the inhibition of the LH surge by progesterone in rats [ 41 ], available evidence would suggest that in sheep, progesterone has only limited effects at the level of the pituitary gland, and that it acts primarily via a central hypothalamic mechanism to inhibit GnRH secretion [ 12 , 33 ]. The demonstration in the present study that progesterone can disrupt activation of the GnRH surge is of interest with regard to the mechanisms by which other physiological insults disrupt the estradiol-induced GnRH surge.
The activation stage, therefore, may be central to the integration of physiological information from diverse sources about the overall suitability of the environment internal and external for expression of the preovulatory surge. However, this does not mean that the induction of the preovulatory surge cannot be stopped at some point after activation, such as early in the transmission stage [ 33 ]. In this regard, progesterone appears to both inhibit activation and, if activation has occurred, to block transmission of the stimulatory signal from estradiol-responsive cells to GnRH neurons, hereby providing a 2-tiered protection system that prevents ovulation occurring at inappropriate times, such as during the luteal phase and pregnancy.
In conclusion, the results of this study demonstrate that progesterone blocks the LH surge in ewes by disrupting the reading of the estradiol signal during the activation stage of the GnRH surge induction process. Furthermore, the disruptive effect of progesterone during the activation stage appears to be rapid and transient. That exposure to progesterone at a comparable stage of the GnRH surge induction process in rats [ 4 , 24 , 43 ], women [ 44 ], and monkeys [ 45 ] also blocks expression of the surge, suggests that disruption of the estradiol-dependent activation of the positive feedback system by progesterone may be common to all spontaneously ovulating species.
Consequently, the results of the present study could be interpreted as indicating that this action of progesterone is a fundamental mechanism for regulating the timing of ovulation in female mammals. We are grateful to Dr. The estradiol-induced surge of gonadotropin-releasing hormone in the ewe. Endocrinology ; : — Google Scholar. Gonadotropin-releasing hormone requirements for ovulation. Biol Reprod ; 56 : — Estradiol requirements for induction and maintenance of the gonadotropin-releasing hormone surge: implications for neuroendocrine processing of the estradiol signal.
Freeman ME. The neuroendocrine control of the ovarian cycle of the rat. New York : Raven Press ; : — Google Preview. Goodman RL. Neuroendocrine control of the ovine estrous cycle. Steroid feedback inhibition of pulsatile secretion of gonadotropin-releasing hormone in the ewe.
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