***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: PURPOSE To compare outcome following in vitro fertilization-embryo transfer ( IVF-ET ) using controlled ovarian hyperstimulation ( COH ) regimens using either the gonadotropin-releasing hormone ( GnRH ) agonist leuprolide acetate vs the GnRH antagonist ganirelix . METHODS Women needing IVF for conception were r and omly assigned to 300 IU of gonadotropins with ganirelix used in the follicular phase when a follicle with a 14 mm average diameter was attained vs a regimen using leuprolide acetate from the mid-luteal phase of the previous cycle . RESULTS There were no differences found in clinical , ongoing , delivered pregnancy rates or implantation rates between groups . CONCLUSIONS The use of GnRH antagonists do not seem to reduce IVF outcome compared to using GnRH agonists in COH regimens OBJECTIVE Both gonadotropin-releasing hormone ( GnRH ) analogs and antagonists have been used for pituitary desensitization during controlled ovarian hyperstimulation ( COH ) . We aim ed to determine the minimum effective daily dose of GnRH antagonist in women undergoing COH . We also compared the efficiency of a GnRH antagonist and a GnRH agonist . MATERIAL S AND METHODS Women undergoing in vitro fertilization/intracytoplasmic sperm injection and embryo transfer were divided into five groups : ( 1 ) cetrorelix 0.25 mg ( n = 86 ) ; ( 2 ) cetrorelix 0.2 mg ( n = 28 ) ; ( 3 ) cetrorelix 0.15 mg ( n = 30 ) ; ( 4 ) leuprolide acetate ( LA ) 0.5 mg/day ( n = 58 ) ; ( 5 ) single half-dose LA depot 1.88 mg ( n = 49 ) . Cetrorelix was administered daily from menstrual day 8 until the day of human chorionic gonadotropin administration . LA or LA depot was started on day 21 of the previous menstrual cycle . RESULTS We observed lower gonadotropin ( Gn ) dosages , estradiol ( E2 ) levels and reduced risk of ovarian hyperstimulation syndrome ( OHSS ) in the GnRH antagonist groups . A higher risk of luteinizing hormone ( LH ) surge was noted in cetrorelix 0.2 and 0.15 mg groups . Gn dosages (IU)/E2 levels ( pg/mL ) in each group were : ( 1 ) 1,949.4/1,191.1 ; ( 2 ) 1,869.6/1,010.8 ; ( 3 ) 1,856.7/1,023.6 ; ( 4 ) 2,184.5/1,323.6 ; and ( 5 ) 2,103.5/1,313.5 , respectively . LH/OHSS risks were : ( 1 ) 3.5%/5.8 % ; ( 2 ) 7.1%/3.6 % ; ( 3 ) 13.3%/3.3 % ; ( 4 ) 3.4%/8.6 % ; and ( 5 ) 2%/8.2 % , respectively . Number of oocytes/embryos/ grade I , II embryos were : ( 1 ) 9.4/7.9/5.8 ; ( 2 ) 7.5/4.2/3.6 ; ( 3 ) 6.3/4.1/3.1 ; ( 4 ) 12.3/8.9/6.6 ; and ( 5 ) 11.8/8.4/6.1 , respectively . There was no significant difference in terms of clinical outcomes between groups 1 , 4 and 5 , except for higher abortion rates ( AR ) in group 1 . Pregnancy rate (PR)/implantation rate ( IR ) ratios in groups 1 , 4 , and 5 were statistically higher than those in groups 2 and 3 . Chemical PR/IR/AR were : ( 1 ) 30.2%/5.9%/7 % ; ( 2 ) 21.4%/5.1%/7.1 % ; ( 3 ) 16.7%/4.1%/10 % ; ( 4 ) 32.8%/5.5%/8.6 % ; and ( 5 ) 30.6%/5.7%/8.2 % , respectively . CONCLUSION The lowest effective dosage of cetrorelix for pituitary desensitization during COH luteolysis is 0.25 mg , result ing in a comparable PR but a higher AR when compared with GnRH agonist Purpose To evaluate the results of gonadotropin-releasing hormone agonist ( GnRHa ) and gonadotropin-releasing hormone antagonist ( GnRHant ) use in two demographically matched groups of normoresponder in-vitro fertilisation or intracytoplasmic sperm injection ( IVF/ICSI ) patients in a prospect i ve study . Methods We r and omised 93 patients undergoing IVF/ICSI between May 2005 and August 2006 . Patients with IVF indications were included except for those with polycystic ovary syndrome or azoospermia , women older than 38 years and those with follicle-stimulating hormone ( FSH ) ≥10 IU/ml . Patients were stimulated with st and ard 225 IU recombinant FSH . In Group I ( n=45 ) a daily dose of GnRHant cetrorelix acetate 0.25 mg was administered when follicles reached a diameter of ≥14 mm . Group II ( n=48 ) patients were desensitised with the GnRHa , leuprolide acetate , in a long protocol . Human chorionic gonadotropin ( hCG ) was administered when at least three follicles of 18 mm in diameter were observed . Oocyte retrieval was scheduled 36 hours following hCG administration and embryos were transferred on day 3 after oocyte retrieval . Results The two groups were homogenous for age , infertility duration , basal FSH and serum oestradiol ( E2 ) ( P=0.537 , P=0.911 , P=0.103 and P=0.733 , respectively ) . In Group II ( the GnRHa group ) more antral follicles ( P<0.001 ) , a longer induction duration ( P=0.017 ) and higher peak E2 levels ( P<0.001 ) were observed . No differences were observed in the number of oocytes retrieved ( P=0.749 ) , embryos achieved and transferred ( P=0.677 ) , or fertilisation rates ( P=0.839 ) between the two groups . There was no statistically significant difference between groups in clinical pregnancy rates , cycle cancellation and ovarian hyperstimulation ( P=0.437 , P=0.109 and P=0.415 , respectively ) . Conclusion GnRHant and GnRHa provide comparable results in normoresponder patients , while GnRHant allows a greater flexibility in their treatment OBJECTIVE To compare the effects of oral contraceptive ( OC ) pill pretreatment in recombinant FSH/GnRH-antagonist versus recombinant FSH/GnRH-agonist stimulation in in vitro fertilization ( IVF ) patients , and to evaluate optimization of retrieval day . DESIGN Prospect i ve , r and omized , multicenter study . SETTING Private practice and university centers . PATIENT(S ) Eighty patients undergoing IVF who met the appropriate inclusion criteria . INTERVENTION(S ) Four study centers recruited 80 patients . The OC regimen began on cycle days 2 to 4 and was discontinued on a Sunday after 14 to 28 days . The recombinant FSH regimen was begun on the following Friday . The GnRH-agonist group was treated with a long protocol ; the GnRH-antagonist was initiated when the lead follicle reached 12 to 14 mm . When two follicles had reached 16 to 18 mm , hCG was administered . MAIN OUTCOME MEASURE(S ) The primary outcome measures were the number of cumulus-oocyte complexes , day of the week for oocyte retrieval , and total dose and days of stimulation of recombinant FSH .  Secondary efficacy variables included pregnancy and implantation rate ; serum E(2 ) levels on stimulation day 1 ; serum E(2 ) , P , and LH levels on the day of hCG administration ; follicle size on day 6 and day of hCG administration ; the total days of GnRH-analogue treatment ; total days on OC ; total days from end of OC to oocyte retrieval ; and the cycle cancellation rate . RESULT ( S ) Patient outcomes were similar for the days of stimulation , total dose of gonadotropin used , two-pronuclei embryos , pregnancy ( 44.4 % GnRH-antagonist vs. 45.0 % GnRH-agonist , P=.86 ) and implantation rates ( 22.2 % GnRH-antagonist vs. 26.4 % GnRH-agonist , P=.71 ) . Oral contraceptive cycle scheduling result ed in 78 % and 90 % of retrievals performed Monday through Friday for GnRH-antagonist and GnRH-agonist . A one day delay in OC discontinuation and recombinant FSH start would result in over 90 % of oocyte retrievals occurring Monday through Friday in both groups . CONCLUSION ( S ) The OC pretreatment in recombinant FSH/GnRH-antagonist protocol s provides a patient-friendly regimen and can be optimized for weekday retrievals . No difference was seen in number of 2PN embryos , cryopreserved embryos , embryos transferred , implantation and pregnancy rates between the two stimulation protocol STUDY QUESTION Is the risk of severe ovarian hyperstimulation syndrome ( OHSS ) similar in a short GnRH antagonist and long GnRH agonist protocol in first cycle IVF/ICSI patients less than 40 years of age ? . SUMMARY ANSWER There is an increased risk of severe OHSS in the  long GnRH agonist group compared with the short GnRH antagonist protocol . WHAT IS KNOWN ALREADY ? : In the most recent Cochrane review , the GnRH antagonist protocol was associated with a similar live birth rate ( LBR ) , a similar on-going pregnancy rate ( OPR ) , and a lower incidence of OHSS ( odds ratio ( OR ) = 0.43 95 % confidence interval ( CI ) : 0.33 - 0.57 ) compared with the traditional GnRH agonist protocol . Previous trials comparing the two protocol s mainly included selected patient population s , a limited number of patients and the applied OHSS criteria differed , making direct comparisons difficult . In two recent large meta-analyses , no significant differences in LBR ( OR = 0.86 ; 95 % CI : 0.72 - 1.02 ) or in the incidence of severe OHSS were reported , while others found a lower LBR ( OR = 0.82 ; 95 % CI : 0.68 - 0.97 ) and a reduced risk of severe OHSS using the GnRH antagonist protocol ( OR = 0.60 ; 95 % CI : 0.40 - 0.88 ) . STUDY DESIGN , SIZE , DURATION Phase IV , dual-centre , open-label , RCT including 1050 women allocated to either short GnRH antagonist or long GnRH agonist protocol in a 1:1 ratio and enrolled over a 5-year period using a web-based concealed r and omization code . This is a superiority study design ed to detect a difference in severe OHSS , the primary outcome , between the two groups with a power of 80 % and stratified for age , assisted reproductive technology ( ART ) clinic and planned fertilization procedure ( IVF/ICSI ) . The secondary aims were to compare rates of mild and moderate OHSS , positive plasma (p)-hCG , on-going pregnancy and live birth between the two arms . None of the women had undergone previous ART treatment . PARTICIPANTS / MATERIAL S , SETTING , METHODS All infertile women referred for their first IVF/ICSI at two public fertility clinics , less than 40 years of age and with no uterine malformations were asked to participate . A total of 1099 subjects were r and omized , including women with poor ovarian reserve , polycystic ovary syndrome and irregular cycles . A total of 49 women withdrew their consent , thus 1050 subjects were allocated to the GnRH antagonist ( n = 534 ) and agonist protocol ( n = 516 ) , respectively . In total 1023 women started recombinant human follitropin-β ( rFSH ) stimulation , 528 in the GnRH antagonist group and 495 in the GnRH agonist group . All subjects were given a fixed rFSH dose of 150 IU or 225 IU according to age ≤36 years or > 36 years , with the option to adjust dose at stimulation day 6 . Clinical OHSS parameters were collected at oocyte retrieval , and Days 3 and 14 post-transfer . On-going pregnancy was determined by transvaginal ultrasonography at 
    Output:
    
Stimulation days ( mean difference ( MD ) [ 95 % confidence interval ( CI ) ] = -0.8 [ -1.36 , -0.23 ] , P = 0.006 ) , gonadotrophin ( Gn ) dosage ( MD [ 95 % CI ] = -3.52 [ -5.56 , -1.48 ] , P = 0.0007 ) , estradiol ( E2 ) level on the day of human chorionic gonadotrophin ( HCG ) administration ( MD [ 95 % CI ] = -365.49 [ -532.93 , -198.05 ] , P<0.0001 ) , the number of oocytes retrieved ( MD [ 95 % CI ] = -1.41 [ -1.84 , -0.99 ] , P<0.00001 ) , the embryos obtained ( MD [ 95 % CI ] = -0.99 [ -1.38 , -0.59 ] , P<0.00001 ) , incidence of ovarian hyperstimulation syndrome ( OHSS ) ( OR [ 95 % CI ] = 0.69 [ 0.57 , 0.83 ] , P<0.0001 ) were statistically significantly lower in GnRH-ant protocol than GnRH-a long protocol .
GnRH-ant protocol substantially decreased the incidence of OHSS without influencing the pregnancy rate and live birth rate compared to GnRH-a long protocol among patients with normal ovarian reserve