***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 
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    Input: This study was performed to analyze retrospectively outcomes of stimulated in vitro fertilization ( IVF ) cycles where the gonadotropin-releasing hormone ( GnRH ) antagonist was omitted on ovulation triggering day . A total of 92 consecutive IVF cycles were included in 65 women who are undergoing ovarian stimulation with recombinant FSH .  A GnRH antagonist , cetrorelix 0.25 mg/day , was started when leading follicle reached 14 mm in diameter until the day of hCG administration ( Group A , 66 cycles ) or until the day before hCG administration ( Group B , 26 cycles ) . The duration of ovarian stimulation , total dose of gonadotropins , serum estradiol levels on hCG administration day , and the number of oocytes retrieved were not significantly different between the two groups . The total dose of GnRH antagonist was significantly lower in Group B compared to Group A ( 2.7±0.8 vs. 3.2±0.9 ampoules ) . There was no premature luteinization in the subjects . The proportion of mature oocytes ( 71.4 % vs. 61.7 % ) and fertilization rate of mature ( 86.3±19.7 % vs. 71.8±31.7 % ) was significantly higher in Group B. There were no significant differences in embryo quality and clinical pregnancy rates . Our results suggest that cessation of the GnRH antagonist on the day of hCG administration during a flexible multiple-dose protocol could reduce the total dose of GnRH antagonist without compromising IVF results BACKGROUND The evidence underpinning the timing of an oocyte collection in  IVF or ICSI  is limited . The aim of this study was to assess the effect of the follicle diameter size of the dominant follicle on ongoing pregnancy rates . METHODS We conducted a r and omized controlled trial , including women aged between 18 and 43 years who were scheduled for GnRH agonist down-regulated IVF/ICSI treatment in four assisted conception units . Women were r and omized between timing oocyte collection when the leading follicle had a diameter of 22 mm or when the leading follicle had a diameter of 18 mm . The primary end-point was ongoing pregnancy , defined as a viable pregnancy at 12 weeks of gestation . RESULTS The trial had major problems with recruiting patients and after the planned 2 years of recruiting only half of the aim ed 400 inclusion s were obtained . We allocated 97 women to the 22-mm group and 93 women to the 18-mm group . In the 22-mm group more women reached an ongoing pregnancy ( 37 of 97 women , 38 % ) compared with the 18-mm group ( 22 of 93 women , 24 % ) result ing in a relative risk of 1.6 [ 95 % confidence interval ( CI ) : 1.03 - 2.5 ] . In a logistic regression analysis , the timing of oocyte collection , adjusted for female age , IVF/ICSI and centre , was still associated with ongoing pregnancy , although the association was no longer statistically significant ( OR : 2.0 ; 95 % CI : 0.96 - 4.2 ) CONCLUSIONS : This study suggests that delaying the timing of oocyte collection in IVF or ICSI results in better ongoing pregnancy rates , however , larger studies have to be performed to prove or refute these findings . TRIAL REGISTRATION IS RCT N24724622 Ovarian stimulation with a GnRH-a and hMG for IVF treatment offers the potential to extend the period of follicle recruitment and growth free of the restriction imposed by a spontaneous midcycle LH surge . A r and omized trial investigating the impact of extending follicle growth by 1 day result ed in a significantly reduced PR , despite an increase in the number of larger follicles ( greater than or equal to 17 mm ) at the time of hCG . The reason for a reduced PR was not related to the number of ova recovered or embryo quality . This suggests that follicular aging or the duration of estrogen rise may be important This prospect i ve controlled nonr and omized pilot study was conducted to investigate whether split daily doses of recombinant human LH ( rHLH ) is more efficacious than the single daily dose in supporting follicular development and ovulation in primary hypogonadotrophic hypogonadism ( HH ) . Twenty-seven women with HH received a 150 IU fixed daily subcutaneous dose of recombinant human FSH , supplemented by 75 IU daily dose of rHLH given either as a single dose ( n=9 ; single-dose group ) or four equally divided doses ( n=18 ; split-dose group ) . Ovulation was defined by three efficacy end points : at least one follicle ⩾17 mm in diameter , pre-ovulatory serum oestradiol ⩾400pmol/l and a midluteal progesterone ⩾25nmol/l . Although lacking statistical significance , the proportion of women in the rHLH split-dose group who fulfilled all three end points was higher than the single-dose group ( 72.2 % versus 55.6 % ) . Women in the split-dose group achieved higher serum oestradiol concentrations per follicle , endometrial thickness measurements and numbers of follicles than in the single-dose group ( not statistically significant ) . The odds ratio for ovulation rate was 2.08 ( not statistically significant ) . There were no serious untoward side effects . Administering rHLH in split daily doses could provide superior results compared with the traditional single daily dose . We conducted this clinical study to investigate whether a split daily dose protocol of recombinant human LH ( rHLH ) is more efficacious than the single daily dose in supporting follicular development and ovulation in primary hypogonadotrophic hypogonadism ( HH ) . HH is an uncommon entity that can lead to very low or undetectable serum gonadotrophin concentrations . It manifests in anovulation , amenorrhoea and subsequent infertility . Twenty-seven women with HH received a 150 IU fixed daily subcutaneous dose of recombinant human FSH , supplemented by a 75 IU daily dose of rHLH given either as a single dose ( n=9 ; single-dose group ) or four equally divided doses ( n=18 ; split-dose group ) . Ovulation was defined by these three efficacy end points : at least one follicle ⩾17 mm in mean diameter , pre-ovulatory serum oestradiol concentration ⩾400pmol/l and a midluteal progesterone concentration ⩾25nmol/l . The proportion of women in the rHLH split-dose group who fulfilled all three end points was higher than the single-dose group ( 72.2 % versus 55.6 % ) . Women in the split-dose group achieved higher serum oestradiol concentrations per follicle , endometrial thickness measurements and numbers of follicles than in the single-dose group , without statistical significance . Women who received the split-dose regimen were more likely to have ovulation than the other group . We had no serious problematic side effects . Our results suggest that administering rHLH in split daily doses could provide superior results compared to the traditional single daily dose OBJECTIVE To assess the effect of altering the timing of hCG administration on ongoing pregnancy rates in patients stimulated with recombinant FSH ( rec-FSH ) and GnRH antagonists for IVF . DESIGN Prospect i ve , r and omized , controlled trial . SETTING Tertiary referral center . PATIENT(S ) Four hundred thirteen patients undergoing IVF .  INTERVENTION(S ) Rec-FSH stimulation starting on day 2 of the cycle combined with daily GnRH antagonist starting on day 6 of stimulation . Patients were r and omized to receive 10000 IU of hCG either as soon as at least three follicles were > or=17 mm on ultrasound ( early-hCG group , 208 patients ) or 2 days later after this criterion was met ( late-hCG group , 205 patients ) . MAIN OUTCOME MEASURE(S ) Ongoing pregnancy rate . RESULT ( S ) Fertilization rates and number and quality of embryos transferred did not differ between the two groups . However , a significantly lower ongoing pregnancy rate was present in the late-hCG as compared with the early-hCG group ( 25.0 % vs. 35.6 % , respectively ) . CONCLUSION ( S ) Prolongation of the follicular phase in patients stimulated with rec-FSH and GnRH antagonists for IVF does not affect oocyte or embryo quality but is associated with a significantly lower ongoing pregnancy rate OBJECTIVE To determine if there is an optimum time for the administration of human chorionic gonadotropin ( hCG ) after pituitary desensitization with gonadotropin-releasing hormone agonists ( GnRH-a ) has been achieved before ovarian stimulation for in vitro fertilization ( IVF ) . DESIGN Prospect i ve r and omized study . PATIENTS Two hundred forty-seven patients undergoing an IVF treatment cycle who were r and omly divided into three groups . INTERVENTIONS All patients were administered subcutaneously buserelin acetate 500 micrograms/d from day 1 of the menstrual cycle . After pituitary desensitization had been achieved at least 14 days later , ovarian stimulation with human menopausal gonadotropin was commenced . Ovarian stimulation , cycle monitoring , oocyte recovery , and IVF and embryo transfer ( ET ) techniques were identical in all three groups . Patients in group 1 ( n = 79 ) had hCG administered when the mean diameter of the largest follicle had reached 18 mm , at least two other follicles were greater than 14 mm , and serum estradiol ( E2 ) levels were consistent with the number of follicles observed on ultrasound . Patients in groups 2 ( n = 84 ) and 3 ( n = 84 ) had hCG administered 1 day and 2 days , respectively , after the above criteria had been reached . RESULTS The mean day of hCG administration ( P less than 0.01 ) , maximum serum E2 concentration ( P = 0.06 ) , number of days of serum E2 rise ( P = 0.03 ) , and mean diameter of the largest follicle ( P less than 0.0001 ) were significantly different . There were , however , no significant differences in the mean number of preovulatory and medium size follicles , number of oocytes recovered or embryos transferred . There were also no significant differences in the oocyte recovery , fertilization and cleavage rates , in the number of embryos frozen , or in the pregnancy rates per initiated cycle and per ET . CONCLUSIONS There is no significant advantage in the precise timing of hCG administration after pituitary desensitization with GnRH-a This r and omized controlled trial investigated whether delaying human chorionic gonadotrophin hormone ( hCG ) administration within an IVF cycle impacts upon clinical outcomes . Participants included 125 women undergoing IVF/ICSI cycles at Leeds Centre for Reproductive Medicine . Subjects were aged 20–36 years , body mass index ( BMI ) 20–30 kg/m2 with a normal FSH level ( < 8 IU/l ) . Administration of hCG took place 35–36 h prior to oocyte retrieval when there were ≥3 follicles ≥17 mm in diameter ( Group A ) , delayed by 1 day ( Group B ) or 2 days ( Group C ) . Outcomes included the number of oocytes retrieved per cycle , fertilization rate and live birth rate . On the day of oocyte retrieval , women in Groups B and C had significantly more mature follicles than Group A , although the number of oocytes retrieved did not differ ( median = 12 in each group ) . Fertilization rates and embryo quality were comparable between groups . Pregnancies and live births per cycle were higher in Groups B and C ( A = 30.8 % , B = 54.1 % , C = 38.7 % ; A = 17.9 % , B = 27.0 % , C = 25.8 % ) , but did not reach statistical significance . Delaying hCG administration had no significant negative impact upon morphological quality of embryos , availability of surplus embryos for freezing or pregnancy outcomes . Postponing hCG may enable increased flexibility of cycle scheduling to avoid weekend procedures This multicentre , r and omized study was performed to assess the efficacy and safety of 0.25 mg ganirelix ( Orgalutran , Antagon ) treatment , using triptorelin ( Decapeptyl ) in a long protocol as a reference treatment . In total , 236 subjects were r and omized to treatment with ganirelix ( 0.25 mg , s.c . ) and 119 to triptorelin ( 0.1 mg , s.c . ) treatment ( treatment ratio 2:1 ) . Treatment with ganirelix started on day 6 of stimulation , whereas treatment with triptorelin started on menstrual cycle day 21 to 24 of the previous cycle ( i.e. the midluteal phase ) . The ganirelix regimen was on average 17 days shorter ( 9 versus 26 days ) compared to the triptorelin regimen . The median total dose of recombinant FSH ( Puregon ) used was 450 IU less ( 1350 versus 1800 IU ) in the ganirelix protocol . The initial follicular growth was faster and , consequently , oestradiol concentrations were higher in the ganirelix group . On the day of human chorionic gonad 
    Output:
    
The fertilization rate was not statistically different between early and 24-h late hCG groups , but it is significantly higher in the 48-h late hCG group .
The pooled results showed no significant differences in the ongoing pregnancy rate per oocyte pick-up , the miscarriage rate and the live birth rate .
CONCLUSION The prolongation of follicular phase by delaying hCG administration could increase estradiol , progesterone levels and oocyte retrieval , which will not influence ongoing pregnancy rate per oocyte pick-up , miscarriage rate and live birth rate .