***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: OBJECTIVE To evaluate the effectiveness of a GnRH antagonist in preventing premature LH surge under a letrozole and gonadotropin protocol . DESIGN Prospect i ve , r and omized clinical trial . SETTING A teaching hospital and tertiary medical center . PATIENT(S ) Sixty-one patients were r and omly assigned into two letrozole and gonadotropin-treated groups . These were distinguished by the absence ( group I ) or presence ( group II ) of supplementation with 0.25 mg of cetrorelix . INTERVENTION(S ) Controlled ovarian stimulation with letrozole and gonadotropins , cetrorelix and intrauterine insemination . MAIN OUTCOME MEASURE(S ) Rate of premature LH surge . RESULT ( S ) Compared with group I , the rate of premature LH surge was statistically significantly lower for group II ( 43.4 % [ 13/30 ] vs. 19.4 % [ 6/31 ] ) , but the amount of gonadotropins used was statistically significantly higher ( 817.5 + /- 28.5 vs. 907.5 + /- 27.3 IU ) . Patients with premature LH surge had a statistically significantly lower pregnancy rate ( 21.4 % [ 9/42 ] vs. 0 [ 0/18 ] ) relative to their unaffected counterparts . CONCLUSION ( S ) A flexible protocol of 0.25 mg of cetrorelix for IUI cycles appears to suppress the rate of premature LH surge during ovarian stimulation with letrozole and gonadotropins . However , the incidence of premature LH surge remains too high , and modification will be necessary before the application of cetrorelix to IVF treatment AIM This prospect i ve study was design ed to assess whether the use of GnRH antagonists can improve the success rate of controlled ovarian stimulation ( COS ) in intrauterine insemination ( IUI ) treatments . PATIENTS AND METHODS Eighty patients were divided into two groups : GnRH antagonist group ( Group A , n=40 ) and  control group ( Group B , n=40 ) . Patients in Group B underwent COS with recombinant Follicle Stimulating Hormone ( r-FSH , 50 - 75 IU/d ) only , while patients in Group A were administered r-FSH ( 50 - 75 IU/d ) plus cetrorelix ( 0.25 mg/d , starting when ≥ 2 follicles ≥ 14 mm were detected on ultrasound scan ) . In both groups a single insemination was performed 36 hours after human Chorionic Gonadotropin ( hCG , 250 mcg ) administration . The primary outcome was clinical Pregnancy Rate ( PR ) . Secondary outcomes were ongoing PR , incidence of Premature Luteinization ( PL ) , number of follicles with mean diameter ≥ 16 mm and between 11 and 15 mm on the day of hCG administration , miscarriage rate , cycle cancellation rate , total amount of r-FSH used and duration of treatment . Student 's t test and Chi-square test were used ( p < .05 statistically significant ) . RESULTS A total of 146 cycles were performed ( Group A : n=72 ; Group B : n=74 ) . A trend towards higher PR in Group A was detected , although it was not statistically significant ( Clinical PR : 18.05 % vs 10.81 % ) . The number of follicles ≥ 16 mm was significantly increased in Group A. The incidence of both premature LH surge and premature luteinization ( PL ) was significantly higher in Group B. No significant differences were found in the duration of the stimulation protocol , and in the total amount of r-FSH administered . CONCLUSIONS The addition of GnRH antagonist in COS/IUI protocol significantly increases the number of mature follicles . However , this multifollicular recruitment is not linked to a significantly higher PR BACKGROUND The study was conducted to compare the results of  intrauterine donor insemination ( DI )  under ovarian stimulation with either clomiphene citrate ( CC ) , in a fixed protocol , or FSH , with ovarian monitoring . METHODS Forty-nine patients were r and omized using a computer-generated list to receive highly purified urinary FSH ( starting dose of 150 IU ) and were subjected to periodic vaginal ultrasound and estradiol determinations . HCG was given when > or = 2 follicles ( > or = 17 mm ) were identified and estradiol reached > 400 pg/ml . Intrauterine insemination ( IUI ) was performed 36 h later . The other 51 received CC on a fixed protocol ( 100 mg/day from the day 5 - 10 of the ovarian cycle ) with HCG being administered on the day 12 , and IUI performed 36 h later . Up to six IUI cycles were performed on all patients if pregnancy was not reached before . Women failing to conceive in the CC group underwent IUI with FSH . The main outcome measures were intrauterine gestational sac observed by transvaginal ultrasound , per cycle and per woman pregnancy rate ( PR ) and multiple PR . RESULTS The per cycle PR was significantly higher in the FSH group , 14.4 % ( 30/209 ) versus 6.1 % ( 16/261 ) , as well as the per woman PR , 61.2 % ( 30/49 ) versus 31.4 % ( 16/51 ) . 12.5 % ( 2/16 ) of pregnancies obtained in the CC group were multiple , compared with 20 % ( 6/30 ) in the FSH group . There were no triplets or higher order pregnancies in CC versus two in FSH ( 6.7 % of pregnancies ) . Patients failing to conceive with CC , who later underwent intrauterine DI with FSH , had similar results to the primary FSH group : 54.3 % PR per patient ( 19/35 ) and 16.0 % per cycle ( 19/118 ) , with a multiple PR of 31.6 % ( 6/19 ) . The PR for women starting with CC cycles and , if pregnancy was not obtained , continuing with six FSH cycles , was 69.2 % . CONCLUSIONS The PR obtained with CC stimulation was approximately half that obtained with FSH . There was a trend to lower multiple PR with CC . It is recommended that each case should be considered on an individual basis and the treatment options discussed with patients . In our opinion , CC could be a reasonable approach for young women with good prognosis , whereas in the remaining cases FSH would be the preferable method OBJECTIVE To evaluate the effect of the gonadotropin-releasing hormone antagonist Ganirelix on gonadotropin ovulation induction ( OI ) in patients with polycystic ovary syndrome ( PCOS ) . DESIGN Prospect i ve , r and omized , controlled study . SETTING Academic infertility center . PATIENT(S ) Ninety-eight anovulatory women with PCOS undergoing 154 gonadotropin OI cycles . INTERVENTION(S ) Patients were treated with recombinant FSH alone ( group 1 ) or in conjunction with Ganirelix when the leading follicle was ≥13 mm ( group 2 ) versus from the beginning of stimulation ( group 3 ) , followed by IUI . MAIN OUTCOME MEASURE(S ) Per cycle clinical pregnancy rate ( CPR ) , live-birth rate ( LBR ) , total gonadotropin dose , days of stimulation , serum LH and peak E2 , and premature luteinization rate . RESULT ( S ) Data are suggestive of improved CPR in group 2 versus group 1 ( 33 % vs. 19 % ) and LBR ( 35 % vs. 20 % ) but not significantly different . Premature luteinization was highest in group 1 ( 21 % vs. 1.8 % in group 2 and 2.1 % in group 3 ) . Group 3 had the highest cancellation rate and cost without improving CPR and LBR . No differences were noted in peak serum E2 , total gonadotropin dose , or days of stimulation . CONCLUSION ( S ) Adding Ganirelix in a flexible protocol to gonadotropin OI cycles in women with PCOS may be beneficial by decreasing premature luteinization BACKGROUND Our prospect i ve r and omized controlled trial was design ed to assess whether the use of GnRH antagonists can improve the success rate of controlled ovarian stimulation (COS)/intrauterine insemination ( IUI ) treatments , via inhibition of the premature LH rise . METHODS A total of 104 patients were r and omly divided , using a r and omization list , into two groups : in group A ( n = 52 ) , recombinant FSH ( rFSH ) was given with GnRH antagonist Cetrorelix , and in group B ( n = 52 ) , the patients received rFSH alone in a manner similar to that of group A. The primary outcome measure was clinical pregnancy rate per couple . RESULTS The pregnancy rate per patient was 53.8 % in group A and 30.8 % in group B ( P = 0.017 ) . The rate of premature LH surge was 7 % in group A and 35 % in group B ( P < 0.0001 ) . A premature luteinization was observed in two cycles of 144 in group A ( 1.4 % ) and in 16 cycles of 154 in group B ( 10.4 % ) ( P = 0.001 ) . The mean values of LH and progesterone were significantly lower in patients receiving GnRH antagonist than in those who did not ( 3.3 + /- 3.3 mIU/ml in group A versus 9.9 + /- 7.9 mIU/ml in group B , P < 0.0001 , for LH ; 1.3 + /- 1.1 ng/ml versus 2.1 + /- 1.9 ng/ml for group A and B , respectively , P < 0.0001 , for progesterone ) . CONCLUSION The use of GnRH antagonist in COS/IUI cycles improves pregnancy rate , preventing the premature LH rise and luteinization BACKGROUND The usefulness of GnRH antagonists in mild controlled ovarian hyperstimulation ( COH ) and intrauterine insemination ( IUI ) cycles is debated . METHODS Two-hundred and ninety-nine couples with unexplained or mild male factor infertility were enrolled in this international multicentre r and omized controlled trial . Women allocated to the GnRH antagonist group ( n=148 ) received 50 IU recombinant FSH starting on day 3 of the menstrual cycle and Ganirelix 0.25 mg daily starting from the day in which a follicle with a mean diameter of 13 - 14 mm was visualized at ultrasound . Women allocated to the control group ( n=151 ) were administered only 50 IU recombinant FSH starting on day 3 of the menstrual cycle . Couples were recruited only for their first treatment cycle . The primary outcome was the clinical pregnancy rate per initiated cycle . RESULTS Baseline characteristics of the two treatment groups were similar . Clinical pregnancy rates per initiated cycle in women who did and did not receive GnRH antagonists were 12.2 and 12.6 % , respectively ( P=1.00 ) . The relative risk of conception ( 95 % confidence interval ) for the use of GnRH antagonists was 1.0 ( 0.5 - 1.9 ) . CONCLUSIONS In mild COH and IUI cycles , any benefit of the use of GnRH antagonists in improving pregnancy rates is < 2-fold increase BACKGROUND We aim ed to assess the efficacy of a GnRH antagonist in intrauterine insemination ( IUI ) cycles to increase number of mature ovulatory follicles and pregnancy rates . METHODS Prospect i ve r and omized study . Women ( 18 - 38 years old ) with primary / secondary infertility were included . Eighty-two patients were r and omly assigned to  controlled ovarian stimulation  ( COS ) consisting of rFSH + GnRH antagonist or rFSH alone . RESULTS A non-significant increase in the total amount of rFSH was seen in the GnRH antagonist group ( 707+/-240 IU ) with respect to the control group ( 657+/-194 IU ) . The number of mature follicles ( > or = 16 mm ) was significantly higher in the GnRH antagonist group than in the control group ( 2.4+/-1.4 versus 1.7+/-1.2 , P<0.05 ) . Pregnancy rates were significantly increased in the group of patients receiving the GnRH antagonist ( 38 % ) compared to the control group ( 14 % ) . The only non-single pregnancy ( triplets ) occurred in the antagonist group . CONCLUSIONS In this preliminary study , adding the GnRH antagonist to the COS protocol for IUI cycles significantly increased pregnancy rates . Nevertheless , these results may not be associated directly with the antagonist itself but with the fact that more mature ovulatory follicles are present by the day of the hCG . Finally , the risk for multiple gestations needs to be carefully evaluated Several regimens have been developed to administer gonadotropin-releasing hormone agonists in association with human menopausal gonadotropins ( hMG ) during follicular growth stimulation for in vitro fertilization . The aim of this 
    Output:
    
This meta- analysis suggested that GnRH-ant can reduce the incidence of PL and increase the CPR when used in COS/IUI cycles , and it was especially useful for non-PCOS patients .