***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: The clinical application of gonadotrophin-releasing hormone ( GnRH ) antagonists instead of GnRH agonists , to prevent spontaneous premature luteinizing hormone surge during ovarian stimulation for assisted reproduction treatment has been advocated . A recent , double-blind , dose-finding study , including six dosages of the GnRH antagonist ganirelix , in women undergoing ovarian stimulation with recombinant follicle stimulating hormone ( FSH )  , has indicated that high doses of GnRH antagonist ( 1 or 2 mg once daily ) are associated with a low implantation rate . This follow-up study reports on the pregnancy rate after replacement of cryopreserved embryos obtained in stimulation cycles of the above-mentioned trial . Ovarian stimulation was initiated on day 2 of the cycle , with daily injections of 150 IU recombinant FSH . Ganirelix ( 0.0625 , 0.125 , 0.25 , 0.5 , 1.0 or 2.0 mg ) was administered once daily from stimulation day 6 onwards , up to and including the day of human chorionic gonadotrophin . Retrieved oocytes were fertilized by in-vitro fertilization ( IVF ) or intracytoplasmic sperm injection and a maximum of three fresh embryos was transferred . Excess embryos were frozen , and subsequently used in either natural or programmed cycles . Until June 1998 , 11 ongoing pregnancies ( 12 - 16 weeks after embryo transfer ) were achieved from 46 cycles in which embryos had been first frozen ( 23.9 % per transfer ) . Six of these 11 patients had been treated with a high dose of ganirelix ( 1.0 or 2.0 mg ) during the IVF cycles in which the embryos were obtained . In conclusion , our data suggest that high dosages of ganirelix do not adversely affect the potential of embryos to establish clinical pregnancy in freeze-thaw cycles There has been much debate about the role of luteinizing hormone ( LH ) during follicle stimulating hormone (FSH)-treated ovarian stimulation for assisted reproduction , where the endogenous LH is suppressed using a gonadotrophin-releasing hormone analogue . The requirement for LH in oestradiol bio synthesis is established , but other effects of ' insufficiency ' are less clear , and little attention has been paid to the specific origin of the FSH used . The aim of this study was to examine the roles of profoundly suppressed circulating LH concentrations in cycles of ovarian stimulation for IVF , which were affected in two large separate cohorts of patients undergoing assisted reproduction . They were stimulated by either purified urinary FSH ( MHP ) or recombinant human FSH ( rFSH ) . Within each data set , outcomes were examined with respect to the circulating concentrations of LH in the mid-follicular phase , as plasma sample s were stored prospect ively , and assayed retrospectively . Patients with profoundly suppressed LH showed much reduced oestradiol concentrations at mid-follicular phase and at human chorionic gonadotrophin administration in cycles treated with either MHP or rFSH . However , gross ovarian response , as became evident by FSH dose dem and s , duration of stimulation , and also oocyte and embryo yields and embryo cryopreservation were influenced only in cycles treated with MHP . Furthermore , no effect upon pregnancy survival was observed . Thus , it is concluded that there is a dem and for additional exogenous LH treatment only in cycles treated with purified urinary FSH where the LH is profoundly suppressed BACKGROUND The significance of suppressed LH levels in GnRH antagonist cycles for IVF outcome is currently unknown . The purpose of this study was to evaluate prospect ively the association between LH levels and ongoing pregnancy achievement after GnRH antagonist initiation in IVF cycles . METHODS Ovarian stimulation with a fixed dose of 200 IU recombinant FSH and daily GnRH antagonist ( ganirelix ) 0.25 mg from day 6 of stimulation was initiated in 116 women . Patients were not pretreated with an oral contraceptive . Induction of final oocyte maturation was performed with HCG 10,000 IU as soon as three follicles of > or = 17 mm were present in ultrasound , and was followed by oocyte pick-up , conventional IVF or ICSI , and embryo transfer . The luteal phase was supplemented with vaginal progesterone . RESULTS A significant decrease of both ongoing pregnancy rate and implantation rate was present across groups of patients with increasing LH levels . The highest implantation rate and ongoing pregnancy rate was present in those patients with LH levels on day 8 of stimulation < or = 0.5 IU/l . CONCLUSIONS Profound suppression of LH on day 8 of stimulation is associated with a significantly higher chance of achieving an ongoing pregnancy . More studies are necessary to evaluate this phenomenon further The impact of suppressed concentrations of circulating luteinizing hormone ( LH ) during ovarian stimulation on the outcome of in-vitro fertilization or intracytoplasmic sperm injection treatment in 200 consecutive , normogonadotrophic women ( couples ) was analysed retrospectively . A st and ard stimulation protocol with mid-luteal gonadotrophin-releasing hormone ( GnRH ) agonist down-regulation and ovarian stimulation with recombinant follicle stimulating hormone ( FSH ) was used in all cases . Blood was sample d from each woman on stimulation days 1 and 8 for analysis of oestradiol and LH in serum . A threshold value of serum LH of 0.5 IU/l on stimulation day 8 ( S8 ) was chosen to discriminate between women with low or ' normal ' LH concentrations . Low concentrations of LH on S8 ( < 0.5 IU/l ) were found in 49 % ( 98/200 ) of the women . This group of women was comparable with the normal LH group with regard to pre-treatment clinical parameters , and to the parameters characterizing the stimulation protocol with the exception of serum oestradiol concentration , which on S8 was significantly lower than in the normal LH group ( P < 0.001 ) . The proportion of positive pregnancy tests was similar in the two groups ( 30 % versus 34 % per started cycle ) , but the final clinical treatment outcome was significantly different , with a five-fold higher risk of early pregnancy loss ( 45 % versus 9 % ; P < 0.005 ) in the low LH group and consequently a significantly poorer chance of delivery than in the normal LH group . It is concluded that a substantial proportion of normogonadotrophic women treated with GnRH agonist down-regulation in combination with FSH , devoid of LH activity , experience LH suppression , which compromises the treatment outcome . Whether these women would benefit from supplementation with recombinant LH or human menopausal gonadotrophin during ovarian stimulation , remains to be proven in the future by prospect i ve r and omized trials OBJECTIVE To analyze the role of serum LH and of E2 secretion on IVF-ET outcome in patients stimulated with FSH .  DESIGN Using data from three studies , we analyzed ovarian response to FSH and  IVF-ET  outcome from two st and points : [ 1 ] serum LH and [ 2 ] serum E2 on the day of hCG administration divided by the number of retrieved oocytes . SETTING Twenty-six academic and private clinical centers . PATIENT(S ) Three hundred twenty-three ovulatory patients eligible for IVF-ET .  INTERVENTION(S ) Patients were treated with a GnRH agonist and FSH and underwent IVF-ET . MAIN OUTCOME MEASURE(S ) Follicular development , embryos , and pregnancy rate ( PR ) . RESULT ( S ) Serum LH levels did not correlate significantly with number of oocytes retrieved , E2-oocyte ratio , fertilization rate , or PR . Five patient sub population s were identified on the basis of E2-oocyte ratios : 0 to 70 ( A ) , 70 to 140 ( B ) , 140 to 210 ( C ) , 210 to 280 ( D ) , and > 280 ( E ) pg/mL per oocyte ( conversion factor to SI unit , 3.671 ) . Pregnancy rates were significantly different , i.e. , 5.3 % , 31.3 % , 18.1 % , 23.9 % , and 20.4 % for groups A , B , C , D , and E , respectively . Groups were not different in terms of baseline characteristics , number of follicles , fertilization rates , and number of embryos transferred . CONCLUSION Patients with very low levels of LH respond to FSH alone as well as those with higher LH . The E2-oocyte ratio is a strong index of success rate BACKGROUND When administered in the late follicular phase to prevent an LH surge , GnRH antagonists induce a sharp decrease in serum LH levels that may be detrimental for assisted reproductive technology cycle outcome . Therefore , a prospect i ve study was design ed to assess the effects of recombinant human (r)LH supplementation during GnRH antagonist ( cetrorelix ) administration . METHODS The protocol consisted of cycle programming with oral contraceptive pill , ovarian stimulation with rFSH and flexible administration of a single dose of cetrorelix ( 3 mg ) . A total of 218 patients from three IVF centres were r and omized ( by sealed envelopes or according to woman 's birth date ) to receive ( n = 114 ) or not ( n = 104 ) a daily injection of rLH 75 IU from GnRH antagonist initiation to hCG injection . RESULTS The only significant difference was a higher serum peak E2 level in patients treated with rLH ( 1476 + /- 787 versus 1012 + /- 659 pg/ml , P < 0.001 ) whereas the numbers of oocytes and embryos as well as the delivery rate ( 25.2 versus 24 % ) and the implantation rate per embryo ( 19.1 versus 17.4 % ) were similar in both groups . CONCLUSIONS These results show that in an unselected group of patients , there is no evident benefit to supplement GnRH antagonist-treated cycles with rLH BACKGROUND Suppression of endogenous LH production by mid-follicular phase GnRH-antagonist administration in controlled ovarian hyperstimulation protocol using recombinant ( rec ) FSH preparations void of LH activity may potentially affect ovarian response and the outcome of IVF treatment . The present study prospect ively assessed the effect of using a combination of recFSH and recLH on ovarian stimulation parameters and treatment outcome in a fixed GnRH-antagonist multiple dose protocol . METHODS 127 infertile patients with an indication for IVF or ICSI were recruited and r and omized ( using sealed envelopes ) to receive a starting dose of either 150 IU recFSH ( follitropin alpha ) or 150 IU recFSH plus 75 IU recLH ( lutropin alpha ) for ovarian hyperstimulation . GnRH-antagonist ( Cetrorelix ) 0.25 mg was administered daily from stimulation day 6 onwards up to and including the day of the administration of recombinant HCG ( chorion gonadotropin alpha ) . Gonadotropin dose adjustments were allowed from stimulation day 6 onwards , HCG was administered as soon as three follicles > or = 18 mm were present . The primary outcome parameter was treatment duration until administration of HCG .  RESULTS Exogenous LH did not shorten the time necessary to reach ovulation induction criteria . Serum estradiol ( E(2 ) ) and LH levels were significantly higher on the day of HCG administration in the recLH-supplemented group ( 1924.7 + /- 1256.4 vs 1488.3 + /- 824.0 pg/ml , P < 0.03 ) , and 2.1 + /- 1.4 vs 1.4 + /- 1.5 IU/l , P < 0.01 , respectively ) . CONCLUSIONS Except for higher E(2 ) and LH levels on the day of HCG administration , no positive trend in favour of additional LH was found as defined by treatment outcome parameters Publication bias is defined as any tendency on the part of investigators or editors to fail to publish study results on the basis of the direction or strength of the findings . This may lead to overestimation of treatment effects in published work . Inappropriate decisions about patient management may result . We investigated what proportion of abstract s at the European Society of Human Reproduction and Embryology ( ESHRE ) annual meeting eventually reached full publication , what was the time to publication , and which factors might have affected publication . Among the 2691 abstract s of six ESHRE annual meetings , 151 ( 5.6 % ) reporting r and omized controlled trials ( RCT ) were identified . Comprehensive search es of electronic data bases and h and search ing of the two major journals in the field yielded 79 full publications pertaining to these abstract s. Kaplan-Meier analysis estimated 56 % of RCT abstract s to be eventually published in full , the median time to publication being 32.5 months . Positive outcome ( i.e. significant results ) did not affect the publication rate , and neither did sample size , the subject category , or the native language ( English/non-English ) of the country of origin . Oral presentations result ed in eventual full publication significantly more frequently ( 69 % ) 
    Output:
    
Until further prospect i ve studies modify the existing evidence summarized here , an adverse effect of low endogenous LH levels on the probability of ongoing pregnancy beyond 12 weeks is not a sensible rationale for LH supplementation during ovarian stimulation for IVF using GnRH analogues