***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: OBJECTIVE --To evaluate the effect of support with human chorionic gonadotrophin in the luteal phase in women taking part in an in vitro fertilisation programme after buserelin and human menopausal gonadotrophin were used to hyperstimulate their ovaries . DESIGN --Controlled group comparison . SETTING --Outpatient department of a private hospital . PATIENTS --115 Women with indications for in vitro fertilisation , all of whom had at least one embryo transferred . INTERVENTIONS --After suppression of the pituitary with buserelin the ovaries of all the women were stimulated with human menopausal gonadotrophin on day 4 of the luteal phase . Human chorionic gonadotrophin ( 10,000 IU ) was given to induce ovulation , and oocytes were recovered 34 hours later . Embryos were transferred 46 to 48 hours after insemination . Women who had received the 10,000 IU of human chorionic gonadotrophin on a date that was an uneven number ( n = 61 ) were allocated to receive support doses of 2500 IU human chorionic gonadotrophin three and six days after that date . The remaining 54 women did not receive hormonal support . END POINT -- Determination of the rates of pregnancy . MEASUREMENTS and main results --Support with human chorionic gonadotrophin did not significantly alter the progesterone or oestradiol concentrations in the early or mid-luteal phase . The mean ( range ) progesterone concentrations in the late luteal phase in women who did not become pregnant were , however , significantly higher in those who received support ( 16(9 - 110 ) nmol/l nu 8(4 - 46 ) nmol/l ) , and the luteal phase was significantly longer in this group ( 14 days nu 12 days ) . The rate of pregnancy was significantly higher in the women who received support than in those who did not ( 25/61 nu 8/54 ) . CONCLUSIONS --When buserelin and human menopausal gonadotrophin are used to hyperstimulate ovaries support with human chorionic gonadotrophin in the luteal phase has a beneficial effect on in vitro fertilisation This study aim ed to compare the efficacy of micronized progesterone administered as luteal support following ovulation induction for in-vitro fertilization (IVF)- embryo transfer in cycles using gonadotrophin-releasing hormone agonist  , either orally ( 200 mgx4/day ) or vaginally ( 100 mgx2/day ) and to characterize the luteal phase hormonal profile during such treatments . A total of 64 high responder patients requiring intracytoplasmic sperm injection due to male factor infertility were prospect ively r and omized into two treatment groups . Patients treated orally or vaginally were comparable in age ( 31.9 + /- 6.1 versus 30.6 + /- 5.2 ; mean + /- SD ) , number of oocytes retrieved  ( 17 + /- 8.2 versus 18 + /- 7.0 ) , and number  of embryos transferred  ( 3.1 + /- 1.2 versus 2.7 + /- 0.9 ) per cycle . Following low dose vaginal treatment , a significantly higher implantation rate ( 30.7 versus 10.7 % , P < 0.01 ) , but similar clinical pregnancy rate ( 47.0 versus 33.3 % ) and ongoing pregnancy rate ( 41.1 versus 20.0 % ) was observed , compared with oral treatment . In conception cycles , luteal serum progesterone and oestrogen concentrations did not differ between the treatment groups . In non-conception cycles , late luteal progesterone concentrations were significantly lower following vaginal treatment . As low dose micronized progesterone administered vaginally is simple , easy and well tolerated , it could be recommended as the method of choice for luteal support , especially for high responder patients at risk for ovarian hyperstimulation syndrome Background . A prospect i ve study was done to compare the efficacy of luteal phase support ( LPS ) using either three times hCG  ( group I , n=77 ) , hCG on the day of embryo transfer ( ET ) in combination with daily vaginal progesterone  ( group II , n=62 ) or vaginal progesterone only  ( group III , n=70 ) A total of 156 patients were r and omly treated with exogenous natural progesterone ( intramuscularly , 50 mg/day ) and vaginal gel ( 90 mg/day ) P or nothing ( Controls ) from the day before embryo transfer ( ET ) for two weeks . In case of positive beta-HCG , the treatment was continued for 12 weeks . Plasma P and 17 beta-Estradiol concentrations were estimated and compared with the control not supplemented group . Both treatments were able to increase significantly the luteal plasmatic values of P versus controls . The ongoing pregnancy and the living birth rates per transfer were significantly higher in the patients supplemented with intramuscular P than in those treated with vaginal gel P. The intramuscular natural P appears the most suitable route of administration for luteal phase support in IVF-ET procedures In an attempt to determine the best luteal support in in-vitro fertilization ( IVF ) cycles treated with gonadotrophin-releasing hormone agonist ( GnRHa ) and human menopausal gonadotrophin ( HMG ) by the ultrashort protocol , 60 patients were prospect ively r and omized for either  i.m . progesterone or human chorionic gonadotrophin ( HCG ) luteal support . The two groups did not differ in the mean number of oocytes retrieved and embryos replaced , nor in the mean age of the patients and the amount of HMG used . HCG maintained higher levels of oestradiol and progesterone during the luteal phase . Conception rate was significantly higher in the HCG group . We conclude that HCG is superior to i.m . progesterone as luteal support in IVF cycles in which GnRHa is used in the ultrashort protocol Gonadotrophin-releasing hormone agonists ( GnRHa ) are widely used in in-vitro fertilization ( IVF ) for the prevention of a premature rise in luteinizing hormone ( LH ) concentrations . However , the administration of GnRHa during the follicular phase may also impair subsequent luteal function due to retarded recovery of pituitary gonadotrophin secretion . Therefore , luteal supplementation is generally applied . The present study was design ed to determine whether a premature LH surge would still be prevented after early cessation of GnRHa during ovarian stimulation and whether subsequent luteal phase LH production would be sufficient to support progesterone synthesis by the corpus luteum . Sixty patients were r and omized for three groups : ( i ) A long GnRHa/human menopausal gonadotrophin ( HMG ) protocol with luteal support by repeated human chorionic gonadotrophin ( HCG ) ( n = 20 ) , ( ii ) early follicular phase cessation of GnRHa without luteal support ( n = 20 ) , and ( iii ) a long GnRHa protocol without luteal support ( n = 20 ) . Frequent ultrasound and blood sampling was performed during the entire IVF cycle .  Forty normo-ovulatory women served as controls . No premature LH surges were found after early cessation of GnRHa . In this group , some pituitary recovery occurred during the late luteal phase , but this did not affect corpus luteum function . Progesterone concentrations were shown to be dependent on disappearance of the pre-ovulatory bolus of HCG . Pregnancies occurred in all three groups . In conclusion , early follicular phase cessation of GnRHa is still effective in the prevention of a premature rise in LH . Although some pituitary recovery was observed thereafter , corpus luteum function is still abnormal due to early luteolysis This study was conducted to compare the endocrine milieu and pregnancy rates in an in-vitro fertilization and embryo transfer ( IVF-ET ) programme employing a gonadotrophin-releasing hormone agonist ( GnRHa ) and human menopausal gonadotrophin ( HMG ) when either human chorionic gonadotrophin ( HCG ) or progesterone were used for luteal phase support . A total of 121 IVF-ET treatment cycles were prospect ively studied . All patients started leuprolide acetate in the midluteal phase and it was continued for at least 10 days . When oestradiol levels were less than 150 pmol/l , HMG was started . When at least three follicles were greater than or equal to 17 mm in diameter , HCG 5000 IU i.m . was given . Oocytes were retrieved using transvaginal ultrasound and embryos were transferred 48 h later . The patients ' cycles were prospect ively r and omized to receive HCG ( 72 cycles ) or progesterone ( 49 cycles ) luteal support . The HCG group received 1500 IU i.m . on days 3 , 6 and 9 after the initial trigger . The progesterone group received 12.5 mg i.m . q.d . starting from the day after the HCG trigger . The dose of progesterone was increased to 25 mg i.m . q.d . starting on the day of embryo transfer and continued for 17 - 21 days . If the patient became pregnant , this dose of progesterone was continued until fetal heart activity was visualized by ultrasound . Mean ages , number of eggs retrieved , embryos transferred , oestradiol levels on the day of the HCG trigger , oestradiol and progesterone at the time of embryo transfer were the same in both groups . ( ABSTRACT TRUNCATED AT 250 WORDS OBJECTIVE To evaluate the possible role for estrogen supplementation to the P luteal phase support of GnRH agonists (GnRH-a)- and hMG-induced IVF-ET  cycles . SETTING In vitro fertilization unit in a tertiary care university hospital . DESIGN A prospect ively r and omized study . PATIENTS One hundred consecutive patients undergoing ET after IVF were assigned into one of two luteal supplementation regimens . INTERVENTIONS In all patients enrolled in the study , ovulation was induced using the midluteal regimen for pituitary down regulation with GnRH-a followed by follicular stimulation with hMG . The first group received IM P 50 mg/d , as luteal phase support , starting the day of ET . The second group received the same dosage of P , combined with oral E2 valerate , 2 mg/d . Serum levels of P and E2  were monitored every 4 days for 16 days after ET . MAIN OUTCOME MEASURES Pregnancy rates ( PRs ) and live birth rates per ET . RESULTS No significant difference in E2 or P levels throughout the cycle was observed between groups . Similar PRs per ET and the live birth rates were also observed between group A and B ( 28 % versus 26.5 % and 78.6 % versus 76.1 % , respectively ) . CONCLUSION No advantage was found in the addition of E2 valerate to P luteal phase support of GnRH-a- and hMG-induced IVF-ET cycles The luteal phase hormone profiles of two groups participating in the Yale in vitro fertilization ( IVF ) program were compared . A control group ( group I ) consisted of 28 women ( 28 cycles ) who received our st and ard ovulation induction regimen ( no luteal phase support ) .  The treatment group ( group II ) consisted of 40 women ( 42 cycles ) who were prospect ively studied after receiving luteal phase support with 10,000 IU human chorionic gonadotropin ( hCG ) 5 days after the initial hCG dose . The groups were matched for age and cause of infertility . Estradiol ( E2 ) and progesterone ( P ) were measured on the day of embryo transfer and every 3 to 4 days thereafter . Luteal phase hCG support significantly augmented ( 1 ) E2 and P levels in the conception cycles of group II compared with group I and ( 2 ) P levels in the nonconception cycles of group II compared with group I. The midluteal decline in E2 and P that was observed in group I was minimized or prevented in group II . An ongoing pregnancy rate of 19 % was achieved in group II . This was not statistically different from the 13 % ongoing pregnancy rate noted in a separate group of 163 tubal factor couples undergoing IVF after our st and ard ovulation induction regimen during the period of the study . In summary , the luteal phase hormone profiles of IVF cycles were improved by supplementation with hCG . It is concluded that this type of intervention may serve to rescue potentially failing corpora lutea and thereby optimize the peri-implantation hormonal milieu Two progesterone presentations , a vaginal application of 90 mg progesterone per day ( Crinone ) or 300 mg progesterone administered orally ( Utrogestan ) , were compared for luteal phase support of patients undergoing an in-vitro fertilization ( IVF ) procedure . A total of 283 patients were r and omly allocated to either treatment . The treatment started within 24 h after the embryo transfer procedure and continued until day 30 in cases of implantation . Efficacy was assessed using the pregnancy and delivery rates . Safety was assessed through specific 
    Output:
    
RESULTS Luteal supplementation with either i.m .
hCG or i.m .
progesterone significantly improved fertility outcomes compared with no treatment .
When comparing i.m .
progesterone with i.m .
hCG , no fertility differences were found .
Intramuscular progesterone conferred the most benefit compared with oral or vaginal use .
Addition of oral estrogen to progesterone also improved implantation rates .
CONCLUSION Given the increased risk of ovarian hyperstimulation syndrome associated with hCG use , i.m .
progesterone is favoured for luteal phase supplementation with the addition of estrogen