***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: BACKGROUND Use of letrozole , a selective inhibitor of aromatase , reduces the gonadotrophin dose required to induce follicular maturation . We evaluated whether incorporation of letrozole could be an effective low-cost IVF protocol for poor responders . METHODS A r and omized , controlled , single-blind trial was conducted in the Assisted Reproduction Unit , Institute of Reproductive Medicine , Kolkata , India . Thirty-eight women with a history of poor ovarian response to gonadotrophins were recruited . Thirteen women ( Let-FSH group ) received letrozole 2.5 mg daily from day 3 - 7 , and recombinant FSH ( rFSH ) 75 IU/day on days 3 and 8 ; and 25 women ( GnRH-ag-FSH group ) underwent long GnRH agonist protocol and stimulated with rFSH ( 300 - 450 IU/day ) . Ovulation was triggered by 10,000 IU of HCG followed by IVF-embryo transfer . The main outcome measures were total dose of rFSH ( IU/cycle ) , terminal estradiol ( E2 ) ( pg/ml ) , numbers of follicles , oocytes retrieved and transferable embryo , endometrial thickness ( mm ) , and pregnancy rate . RESULTS Compared with the GnRH-ag-FSH group ( 2865 + /- 228 IU ) , the Let-FSH group ( 150 + /- 0 IU ) received a significantly ( P < 0.001 ) lower total dose of FSH .  Except for terminal E2 , which was significantly higher ( P < 0.001 ) in the GnRH-ag-FSH group ( 380 + /- 46 pg/ml ) than the Let-FSH group ( 227 + /- 45 pg/ml ) , the treatment outcomes in all other respects , including pregnancy rate , were statistically comparable . CONCLUSIONS Adjunctive use of letrozole may form an effective means of low-cost IVF protocol in poorly responding women OBJECTIVE To compare fixed daily doses of the recombinant FSH ( rFSH ) Gonal-F ( 150 IU vs. 225 IU ) for ovarian stimulation in IVF-ET . DESIGN Single-center prospect i ve , r and omized study . Assisted conception unit of a university hospital . One hundred twenty-four women aged 23 - 41 years participated in the study . Exclusion criteria were as follows : FSH of > 10 IU/L , polycystic ovarian syndrome , one ovary or previous ovarian surgery , previous poor response to ovarian stimulation , or ovarian hyperstimulation syndrome ( OHSS ) . INTERVENTION(S ) R and omized to commence 150 IU or 225 IU of Gonal-F per day without dose alterations during treatment . MAIN OUTCOME MEASURE(S ) Number of oocytes retrieved and total rFSH dose . RESULT ( S ) More oocytes were retrieved in women aged < or=32 years in the 225-IU compared with the 150-IU group ( 11.8 + /- 8.0 vs. 7.0 + /- 5.8 ) . In older women ( > or=33 years ) , the number of oocytes retrieved in the two groups were similar . No significant differences were found for fertilization rate , number of embryos formed and cryopreserved , and pregnancy rates between the two groups . The total rFSH dose used was higher in the 225-IU group ( 2,595.0 + /- 510.0 vs. 1,897.5 + /- 457.5 IU ) . The cancellation rate due to insufficient ovarian response was higher in the 150-IU group ( 15.0 % vs. 3.3 % ) . All cases of ovarian hyperstimulation syndrome ( n = 4 ) occurred in the 225-IU group . CONCLUSION ( S ) Two hundred twenty-five IU is more effective than 150 IU in younger women but requires a higher total dose of Gonal-F. The use of 225 IU in older women did not result in a higher oocyte yield , suggesting that 225 IU of rFSH does not compensate for the age-related decline in the number of follicles available for stimulation The management of poor responders in IVF has always been a big problem . The ideal approach has yet to be formulated . In this study we aim to compare two alternative stimulation protocol s. A total of 48 poor responder patients described from previous cycles were included and grouped into two : group I consisted of 24 patients in 24 cycles in which leuprolide acetate ( 40 microg s.c . per day ) was initiated on cycle day 2 followed by exogenous gonadotrophins on cycle day 3 ; group II consisted of 24 patients in 24 cycles in which ovarian stimulation included gonadotrophin-releasing hormone ( GnRH ) antagonist ( cetrorelix , 0.25 mg daily during late follicular phase ) administration . While only the oestradiol concentrations on the day of HCG were lower in group II compared with group I , the clinical pregnancy and implantation rates among groups did not show any significance . The impact of these two regimens in ovarian stimulation of poor responders seem to be same and to establish these results further r and omized studies with larger sample sizes are required Recent evidence suggests that early cessation of gonadotrophin releasing hormone analogue ( GnRHa ) administration may offer some benefit to low responder patients undergoing IVF . A prospect i ve , r and omized controlled trial was design ed to evaluate whether early cessation of GnRHa in an ovarian stimulation regimen is more beneficial than just increasing the doses of gonadotrophins . Seventy low responder patients ( less than three mature follicles in a previous cycle ) with normal basal follicle stimulating hormone concentrations and a previous cancelled IVF cycle were r and omly allocated into two protocol s : ( i ) non-stop protocol : long GnRHa suppression with high doses of gonadotrophins , and ( ii ) stop protocol , in which GnRHa administration is stopped with the onset of menses , while gonadotrophin doses remained similar to the non-stop protocol . A significantly higher number of mature oocytes were obtained in the study group ( stop protocol ) compared to the control group ( non-stop protocol ) ( 8.7 + /- 0.9 versus 6.2 + /- 0.7 , P : = 0 . 027 ) . The stop protocol reduced the number of ampoules of gonadotrophins required ( 56.6 + /- 2.7 versus 68.0 + /- 3.5 , P : = 0 . 013 ) . Both protocol s result ed in a similar cancellation rate ( 2.7 versus 5.8 % ) ( with no cycles cancelled due to ovulation ) , pregnancy rate ( 14.3 versus 18.7 % ) , and implantation rate ( 12.1 versus 8.8 % ) . The early cessation of GnRHa combined with high doses of gonadotrophins permitted the retrieval of a significantly higher number of oocytes The aim of the study was to investigate the cause of the lower estradiol ( E2 ) concentration in women treated with gonadotropin-releasing hormone ( GnRH ) antagonist  compared with those treated with agonist protocol in in vitro fertilization ( IVF ) . Thirty patients who were known low responders were prospect ively r and omized into two equal groups for IVF treatment . Group 1 used GnRH agonist ( flare-up ) protocol and group 2 used antagonist protocol . The results showed that serum luteinizing hormone ( LH ) levels were significantly higher in the agonist group during the folliculogenesis stage . Despite this higher LH , serum E2 levels were significantly higher in the agonist group on cycle day 2 only , not on day 5 or day 9 . The significantly higher E2 level in the agonist group reappeared on the day of administration of human chorionic gonadotropin ( hCG ) . The rate of folliculogenesis in the antagonist group was faster than in the agonist group ; therefore their E2 production should have been higher on hCG day . Furthermore , the rate of decline in E2 after hCG administration was significantly higher in the antagonist group . These findings , along with the fact that both groups received exogenous LH ( human menopausal gonadotropin ) that should optimize steroidogenesis and make the difference in E2 insignificant , enable us to conclude that GnRH antagonists have a suppressive effect on the production of E2 BACKGROUND The aim of this study was to evaluate the effect of doubling the starting dose of gonadotrophins on the ovarian response in IVF patients with a low antral follicle count ( AFC ) . METHODS Fifty-two patients with an AFC of < 5 follicles of 2 - 5 mm diameter before starting their first IVF cycle participated in this r and omized controlled trial . They were r and omized by opening a sealed envelope , receiving either 150 IU ( group I , n = 26 ) or 300 IU ( group II , n = 26 ) of rFSH as a starting dose . The main outcome measures of the study were number of oocytes , poor response ( < 4 oocytes at retrieval or cancellation due to insufficient follicle growth ) and ongoing pregnancy ( 12 weeks of gestation ) . RESULTS The groups were comparable regarding patient characteristics and outcome of the IVF treatment . The median number of oocytes collected was 3 for both groups ( P = 0.79 ) . The difference in the mean number of oocytes was 0.3 oocytes in favour of group I ( P=0.69 ) . Sixty-five per cent of the patients in group I experienced a poor response and 62 % in group II . The ongoing pregnancy rate was 8 % in group I and 4 % in group II ( P = 0.55 ) . CONCLUSIONS Expected poor response patients , defined as patients with an AFC < 5 , are likely not to benefit from a higher starting dose of gonadotrophins in IVF OBJECTIVE To determine the efficacy of natural-cycle IVF compared with controlled ovarian hyperstimulation in poor responders . DESIGN R and omized , controlled study . SETTING Private center for assisted reproduction . PATIENT(S ) One hundred twenty-nine women who were poor responders in a previous IVF cycle . INTERVENTION(S ) Fifty-nine women underwent 114 attempts of natural-cycle IVF  , and 70 women underwent 101 attempts of IVF with controlled ovarian hyperstimulation with microdose GnRH analog flare . MAIN OUTCOME MEASURE(S ) Number of oocytes retrieved , pregnancy rate ( PR ) per cycle , PR per transfer , and implantation rate . RESULT ( S ) The poor responders treated with natural-cycle IVF and those treated with micro-GnRH analog flare showed similar PRs per cycle and per transfer . The women treated with natural-cycle IVF showed a statistically significant higher implantation rate ( 14.9 % ) compared with controls ( 5.5 % ) . When subdivided into three groups according to age ( < or=35 years , > or=36 - 39 years , > or=40 years ) , younger patients had a better PR than the other two groups . CONCLUSION ( S ) In poor responders , natural-cycle IVF is at least as effective as controlled ovarian hyperstimulation , especially in younger patients , with a better implantation rate BACKGROUND In approximately 12 - 14 % of young normogonadotrophic women treated with a depot GnRH agonist long protocol , the initial ovarian response to recombinant human FSH ( rFSH ) can be suboptimal . We have tested the hypothesis that these women may benefit from recombinant human LH ( rLH ) supplementation in a multicentre , prospect i ve , r and omized trial compared with patients treated with an rFSH step-up protocol . METHODS A total of 260 young normogonadotrophic women undergoing controlled ovarian stimulation with a GnRH agonist long protocol for IVF/ICSI were enrolled . The starting dose of rFSH was 225 IU . One hundred and thirty patients with serum estradiol levels < 180 pg/ml and with at least six follicles with a mean diameter > 5 mm but none > 10 mm on both day 5 and day 8 of stimulation were r and omly allocated to two groups . From the eighth day of stimulation , women in group A ( n=65 ) received 150 IU of rLH in addition to rFSH , while those in group B ( n=65 ) had an increase of 150 IU in the daily dose of rFSH ( step-up protocol ) . One hundred and thirty normally responding women continued monotherapy with rFSH and served as a further control population ( group C ) . RESULTS The mean number of cumulus-oocyte complexes retrieved in group A ( 9.0+/-4.3 ) was significantly higher ( P<0.01 ) compared with group B ( rFSH 6.1+/-2.6 ) but significantly lower compared with group C ( 10.49+/-3.7 , P<0.05 ) . Implantation and pregnancy rates were significantly lower ( P<0.05 ) in the rFSH step-up group ( 10.5 and 29.3 % respectively ) when compared with normal responders ( 18.1 and 47.3 % respectively ) . CONCLUSIONS rLH supplementation is more effective than increasing the dose of rFSH in terms of ovarian outcome in patients with an initial inadequate ovarian response to rFSH alone In a prospect i ve r and omized study , we examined whether 
    Output:
    
There is insufficient evidence to support the routine use of any particular intervention either for pituitary down regulation , ovarian stimulation or adjuvant therapy in the management of poor responders to controlled ovarian stimulation in IVF .