***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: STUDY QUESTION Does hormonal stimulation with corifollitropin alpha ( CFA ) only , mimicking a step down protocol , result in lower incidence of progesterone elevation on the day of hCGtrigger as compared to sustained stimulation with recombinant FSH ( rFSH ) ? SUMMARY ANSWER The current findings support the concept that sustained FSH stimulus contributes to premature progesterone elevation in stimulated IVF cycles . WHAT IS KNOWN ALREADY Serum progesterone rise during the follicular phase of ovarian stimulation for IVF treatment seems to be related to a poorer reproductive outcome . However , the mechanism by which the rise in progesterone is caused is not yet fully understood . STUDY DESIGN , SIZE , DURATION This study was a post hoc analysis of data from two multi-center , r and omized , double-blind , double-dummy , active-controlled , non-inferiority trials , ENGAGE and PURSUE , conducted from June 2006 to January 2008 and from July 2010 to October 2012 respectively . PARTICIPANTS / MATERIAL S , SETTING , METHODS In the ENGAGE- study , 1506 women , aged 18 - 36 years , were allocated to either a single injection of 150 mg CFA or daily injections of 200 IU rFSH in the first week of stimulation , using a st and ard GnRH antagonist protocol . In the PURSUE- study , a total of 1390 women , aged 35 - 42 years , were allocated to either a single injection of 150 mg of CFA or daily 300 IU of rFSH for the first week , again using a st and ard GnRH antagonist protocol . In both trials , daily rFSH was continued until three follicles reached > 17 mm in size . All women had a body weight of between 50 and 90 kg , regular menstrual cycles and an indication for ovarian stimulation before IVF . The incidence of progesterone elevation on day of hCG-trigger in patients with CFA only or rFSH stimulation , and triggered on Day 8 of stimulation , was analyzed . MAIN RESULTS AND THE ROLE OF CHANCE Of patients with CFA only stimulation , 5.4 % ( 13/239 patients ) showed a progesterone elevation above 1.5 ng/ml on day of hCG-trigger , whereas patients with rFSH stimulation had a significant higher incidence of progesterone elevation ( 18.3 % ; 62/339 patients ) ( P < 0.001 ) . LIMITATIONS , REASONS FOR CAUTION Post hoc analysis of data from previously published trials could be considered as a reason for caution . WIDER IMPLICATION S OF THE FINDINGS Future studies should evaluate whether it would be possible to prevent a premature progesterone rise in cycles stimulated with daily FSH by using a step down protocol towards the end of the follicular phase . STUDY FUNDING /COMPETING INTERESTS Financial/ Material Support was provided by Merck & Co. , Inc. , Kenilworth , NJ , USA . Davis Gates is an employee of Merck Sharp & Dohme Corp. , a subsidiary of Merck & Co. , Inc. , Kenilworth , NJ , USA and may own stock and /or hold stock options in the company . Fabiola Beligotti is an employee of MSD , Italy , a subsidiary of Merck & Co. , Inc. , Kenilworth , NJ , USA and may own stock and /or hold stock options in the company . Barbara Lawrenz , Nils Engelmann and Human M. Fatemi have no conflict of interest . TRIAL REGISTRATION NUMBER ENGAGE study : Clinical Trials.gov identifier NTC00696800 . PURSUE- study : NCT01144416 To evaluate the effects of high progesterone prior to oocyte retrieval on the genomic profile of peri-implantation endometrium , we conducted this single-center , prospect i ve cohort study . Depending on whether or not the progesterone level on the day of hCG administration and the day after hCG administration were elevated , a total of 20 women undergoing IVF treatment who did not have fresh embryo transfer were included : Group 1 refers to subjects with normal progesterone level on both days ; Group 2 refers to subjects with normal progesterone level on the day of hCG administration and high progesterone level on the day after hCG administration ; Group 3 refers to subjects with high progesterone level on the day of hCG administration and normal progesterone level on the day after hCG administration ; Group 4 refers to subjects with high progesterone level on both days . Five subjects were included in each group . Endometrial sample s were obtained 7days after hCG administration . We found that high progesterone level prior to oocyte retrieval predominantly affected components of the NK cell mediated cytotoxicity pathway in the endometrium and that significant differences were only seen when progesterone measurements on both the day of and day after hCG administration were considered together Recent studies suggest that elevated late follicular phase progesterone concentrations after ovarian stimulation for IVF may result in embryo-endometrial asynchrony , reducing the chance of successful implantation after fresh embryo transfer . It remains unclear to what extent elevated late follicular phase progesterone levels may occur in unstimulated cycles before frozen-thawed embryo transfer , or what affect they may have on outcomes . In this cohort study , 271 patients r and omized to the modified natural cycle arm of a r and omized controlled trial comparing two endometrial preparation regimens  underwent late follicular phase progesterone and LH testing . A receiver operating characteristic curve was constructed to identify a progesterone cut-off level with the best predictive value for live birth ( progesterone level ≥4.6 nmol/l ) . A total of 24.4 % of patients revealed an isolated elevated serum progesterone of 4.6 nmol/l or greater , and 44.3 % showed an elevated progesterone level in association with a rise in LH . Neither endocrine disruption affected outcomes , with live birth rates of 12.9 % versus 10.6 % ( OR 0.6 , 95 % CI 0.19 to 1.9 ) and 11.9 % versus 17.5 % ( OR 1.6 , 95 % CI 0.79 to 3.1 ) , respectively . Whether monitoring of progesterone and LH in natural cycle frozen-thawed embryo transfer has added clinical value should studied further The impact of a premature elevation of serum progesterone level , the day of hCG administration in patients under controlled ovarian stimulation during IVF procedure , on human endometrial receptivity is still debated . In the present study , we investigated the endometrial gene expression profile shifts during the prereceptive and receptive secretory stage in patients with normal and elevated serum progesterone level on the day of hCG administration in fifteen patients under stimulated cycles . Then , specific biomarkers of endometrial receptivity in these two groups of patients were tested . Endometrial biopsies were performed on oocyte retrieval day and on day 3 of embryo transfer , respectively , for each patient . Sample s were analysed using DNA microarrays and qRT-PCR . The endometrial gene expression shift from the prereceptive to the receptive stage was altered in patients with high serum progesterone level ( > 1.5 ng/mL ) on hCG day , suggesting accelerated endometrial maturation during the periovulation period . This was confirmed by the functional annotation of the differentially expressed genes as it showed downregulation of cell cycle-related genes . Conversely , the profile of endometrial receptivity was comparable in both groups . Premature progesterone rise alters the endometrial gene expression shift between the prereceptive and the receptive stage but does not affect endometrial receptivity STUDY QUESTION Are there differences in estrogen and progesterone secretion in singleton pregnancies , up to Week 11 , between spontaneous pregnancies , after controlled ovarian hyperstimulation and fresh embryo transfer ( COH + ET ) and after frozen embryo transfer in a spontaneous cycle ( FET ) ? SUMMARY ANSWER Serum progesterone and estradiol ( E2 ) concentrations after  COH + ET were higher in early pregnancy , lasting up to Week 7 - 8 , than FET and spontaneous pregnancies , while hormone levels after FET did not differ from spontaneous pregnancies . WHAT IS ALREADY KNOWN The risk of adverse perinatal outcomes after COH + ET seems to be increased when compared with spontaneous pregnancies . One of the reasons suggested for this is related to ovarian hyperstimulation . STUDY DESIGN , SIZE , DURATION This was a prospect i ve cohort study consisting of three different groups of pregnant women which were followed-up weekly until Week 11 of their pregnancies . The spontaneous pregnancy group consisted of 41 women , the COH + ET group consisted of 39 and the FET group consisted of 30 women . PARTICIPANTS / MATERIAL S , SETTING , METHODS Women in the control group with spontaneous conception were recruited from local prenatal clinics . Women in the COH + ET and FET groups were recruited from the Reproductive Unit of Oulu University Hospital . At each visit , a three-dimensional ultrasonography was performed to examine the ovarian volumes and vascularization . A blood sample was drawn to analyse progesterone and E2 levels . The pregnancy outcome was included in the analysis . MAIN RESULTS AND THE ROLE OF CHANCE At pregnancy Week 5 , the serum progesterone levels were higher after the  COH + ET ( median 312 , inter-quartile range 183 - 480 nmol/l ) , when compared with the spontaneous ( 63 , 52 - 80 nmol/l ; P < 0.001 ) and FET ( 74 , 48 - 96 nmol/l ; P < 0.001 ) pregnancies . At Week 11 , the P ( 189 , 124 - 260 nmol/l ) was still higher in the COH + ET group ( FET 101 , 78 - 120 nmol/l , P < 0.001 ; spontaneous 115 , 80 - 139 nmol/l , P < 0.01 ) than the other two groups . The E2 levels at Week 5 were also significantly higher after  COH + ET  ( 4.1 , 2.2 - 6.6 nmol/l ) than in the spontaneous pregnancies ( 1.1 , 0.7 - 1.6 nmol/l , P < 0.001 ) or after FET ( 0.7 , 0.6 - 0.9 nmol/l , P < 0.001 ) . The volume of the ovaries and the intraovarian vasculature in the COH + ET group were significantly higher when compared with the other two groups ( P < 0.001 ) . The birthweight was negatively correlated with the serum P ( R -0.340 , P < 0.01 ) and E2 ( R= -0.275 , P < 0.05 ) in pregnancy Weeks 5 - 8 . In the multivariate analysis evaluating the factors affecting birthweight of the newborn , the significant factors were the length of gestation , maternal height and progesterone or E2 secretion during Weeks 5 - 8 . LIMITATIONS , REASONS FOR CAUTION Because of the low number of patients in this study , larger cohort studies are required to confirm the findings . WIDER IMPLICATION S OF THE FINDINGS The findings here indicate that COH-induced increased luteal activity should be evaluated by measuring steroid levels or the ovarian size or vascularity , rather than number of oocytes retrieved . If unphysiologically high steroid activity during pregnancy after COH contributes to the risk of adverse perinatal outcomes after fresh embryo transfer , milder stimulation protocol s or even freezing of all of the embryos should be considered . STUDY FUNDING /COMPETING INTERESTS This study was supported by a research grant from the Academy of Finl and . The authors declare no conflicts of interest Abstract This study analyzed the clinical outcomes of patients with elevated progesterone level on the HCG day in IVF/ICSI cycles , with different timing of embryo transfer . A total of 123 patients were involved in this prospect i ve r and omized clinical study . Group 1 : blastocyst transfer group , 38 cases ; Group 2 : frozen – thawed embryo transfer group ( first FET cycle ) , 42 cases ; Group 3 : fresh embryo transfer group , 43 cases . The basal FSH level was comparable among three groups ( 6.7 ± 3 versus 7.0 ± 2 versus 6.9 ± 2.4 , p = 0.897 ) . The clinical pregnancy rate was highest in group 2 , lowest in group 3 , with significantly difference ( 31.6 % versus 38.1 % versus 13.9 % , p = 0.037 ) . The implantation rate and live birth rate were still lowest in group 3 ( 21.9 % versus 19.8 % versus 6.7 % , p = 0.016 and 18.4 % versus 31 % versus 11.6 % , p = 0.081 ) . In conclusion , the elevated progesterone level will affect clinical pregnancy rate in fresh embryo transfer cycles . We suggest frozen-thawed embryo transfer for these patients . However , for those patients who expressed 
    Output:
    
Up-to-the minute data show that , there is a different impact of elevated P4 in fresh , frozen and donor cycles , whereas there are plenty of reports pointing to a different endometrial gene expression on different P4 measurements .
Our hypothesis states that the combination of P4 values and endometrial ultrasound parameters at the day of oocyte triggering can affect clinical pregnancy rates in normal responders undergoing ART