***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 determine if an increase in plasma P occurring before hCG administration might impair the outcome of  IVF-ET . DESIGN Five hundred eighty-five IVF-ET cycles were prospect ively studied for the occurrence of plasma P elevation before hCG administration . SETTING Tertiary institution , IVF-ET program , Hôpital A. Béclère . PATIENTS Participating patients included IVF-ET c and i date s 23 to 42 years of age only , excluding the couples in whom a male factor was a primary or an accessory cause of infertility . MAIN OUTCOME MEASURES To clarify the practical consequences on IVF-ET outcome of pre-hCG increases in plasma P , we studied 585 consecutive IVF-ET cycles . These were divided into two groups according to plasma P levels observed on the day of hCG administration ; plasma P of 0.9 ng/mL ( 2.9 nmol/L ) was taken as an arbitrary cutoff value . Group A included 485 IVF cycles in which plasma P was < or = 0.9 ng/mL ( 2.9 nmol/L ) ; group B included the remaining 100 cycles in which plasma P was > 0.9 ng/mL ( 2.9 nmol/L ) . RESULTS The number of mature oocytes retrieved , the oocyte cleavage rate , and the number of embryos obtained were similar in groups A and B. In contrast to this apparent similarity in oocyte quality , a decrease in pregnancy rate ( PR ) and a trend for a decrease in embryo implantation rate were observed in group B in comparison with group A. CONCLUSIONS The similar fertilization and cleavage rates obtained in groups A and B suggest that pre-hCG elevation in plasma P does not lead to decreased oocyte quality . Yet the lower PR observed when plasma P rises prematurely suggests that the prolonged but discrete elevation in plasma P occurring in these cases might alter endometrium receptivity to embryo implantation OBJECTIVE To determine the prevalence and the effect of premature luteinization in  GnRH antagonist IVF-ET cycles . DESIGN Prospect i ve observational study . SETTING In vitro fertilization-embryo transfer ( IVF-ET ) program at the Instituto Valenciano de Infertilidad . PATIENT(S ) Eighty-one infertile patients undergoing controlled ovarian hyperstimulation with gonadotropins and GnRH antagonist for IVF-ET .  INTERVENTION(S ) Gonadotropin-releasing hormone ( GnRH ) antagonist was administered from stimulation day 6 . Serum P , E(2 ) , and LH were determined on the day of hCG administration . MAIN OUTCOME MEASURE(S ) Cycles were grouped according to serum P level on the day of hCG administration ( < 1.2 ng/mL or > or = 1.2 ng/mL ) . Clinical pregnancy and implantation rates were determined . RESULT ( S ) The incidence of premature luteinization was 38.3 % . Total recombinant FSH dose and stimulation days differed significantly between the groups . Pregnancy rate ( 25.8 % vs. 54.0 % ) and implantation rate ( 13.8 % vs. 32.0 % ) were significantly lower in the premature luteinization group . CONCLUSION ( S ) Premature luteinization during GnRH antagonist IVF-ET cycles is a frequent event that is associated with lower pregnancy and implantation rates . Progesterone elevations are not related to serum LH levels and may reflect the mature granulosa cell response to high FSH exposure OBJECTIVE To determine if premature luteinization can occur in  GnRH agonist ( GnRH-a ) and FSH ( recombinant FSH and human urinary FSH ) IVF cycles and whether premature luteinization affects IVF and clinical outcome . DESIGN Retrospective evaluation of 171 IVF-ET cycles . The cycles were divided into two groups according to the P level on the day of hCG : group I ( serum P < /= 0.9 ng/mL [ conversion factor to SI unit , 3.180 ] ) and group II ( serum P > /= 1.1 ng/mL ) . MAIN OUTCOME MEASURES Comparison of cycles characteristics and of cumulative exposure of follicular serum E2 , FSH , LH , and P  as well as of IVF and clinical outcome were made between the study groups . RESULTS Twenty-three of the 171 cycles ( 13.4 % ) demonstrated premature luteinization . The age of the patients , the E2 , and LH exposure were similar between the groups . The number of the ampules of gonadotropins ( recombinant FSH and urinary FSH ) used and the area under FSH and P curve were higher in cycles with premature luteinization . The area under the FSH curve correlated with the area under the P curve . Similar IVF and clinical outcomes were observed in cycles with and without premature luteinization . CONCLUSION The greater FSH exposure and its correlation with the P exposure suggest that one of the possible factors inducing premature luteinization is the increased FSH-induced LH receptivity in granulosa cells . No adverse effects of premature luteinization on the IVF and clinical outcome were observed Our objective was to assess the effects of subtle increases in serum progesterone concentration ( 1.0 - 2.0 ng/ml ) on the outcome of in-vitro fertilization ( IVF ) , particularly on the quality of embryos , during the follicular phase of cycles stimulated with gonadotrophin-releasing hormone agonist ( GnRHa ) and human menopausal gonadotrophin ( HMG ) . A total of 97 patients underwent 116 cycles of IVF  and were stimulated with a combination of HMG and GnRHa . They were divided into two groups : those with a subtle progesterone rise and those with no progesterone rise . The two groups were compared with respect to serum oestradiol , progesterone , immunoreactive luteinizing hormone ( I-LH ) , bioactive LH ( B-LH ) , and results of IVF . The groups did not differ significantly in mean age or in total dose of HMG received . On the day that human chorionic gonadotrophin was administered , concentrations of oestradiol and progesterone were significantly higher in the subtle progesterone rise cycles than in the no progesterone rise cycles . In the no progesterone rise cycles , the percentages for embryos beyond the 4-cell stage , grade 1 embryos , and implantation rates were significantly higher than those in subtle progesterone rise cycles . The combination of GnRHa and HMG eliminated any significant rise in serum I-LH or B-LH concentration during the follicular phase , but did not suppress the subtle rise in progesterone . These results confirm our previous finding that a subtle progesterone rise adversely affects the outcome of IVF . It is also suggested that a reduction in embryo quality may influence the lower rate of implantation in subtle progesterone rise cycles The relationship of the circulating level of progesterone ( P ) on the day of human chorionic gonadotropin ( hCG ) injection to occurrence of clinical pregnancy was examined in 133 leuprolide acetate human menopausal gonadotropin ( hMG ) in vitro fertilization cycles in women having at least three embryos transferred .  Progesterone concentrations greater than 0.5 ng/mL were associated with a significantly lower rate of pregnancy ( 12/59 , 20 % ) compared with less than 0.5 ng/mL ( 40/74 , 54 % , P less than 0.005 ) . The higher P cycles were associated with greater patient age and hMG dose , although these relationships appeared to be indirect . Luteinizing hormone ( LH ) concentrations remained suppressed . Ovarian stimulation may cause excessive luteinization and an adverse cycle outcome even in the presence of low LH levels . Prospect i ve use of P levels may be helpful to determine optimal hCG timing 
    Output:
    
In conclusion , the best available evidence does not support an association between progesterone elevation on the day of hCG administration and the probability of clinical pregnancy in women undergoing ovarian stimulation with GnRH analogues and gonadotrophins for IVF