***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 study and evaluate a sequential , extended embryo culture system . DESIGN Prospect i ve study . SETTING University-affiliated IVF clinic . PATIENT(S ) All couples who were treated between October 1997 and July 1998 . INTERVENTION(S ) A st and ard human tubal fluid plus 10 % serum substitute supplement ( SSS ) culture medium was used . The embryos were transferred to extended culture medium ( S2 or G2 ) on day 3 . MAIN OUTCOME MEASURE(S ) Blastocyst formation and implantation and pregnancy rates . RESULT ( S ) Forty percent of the 20 donated cryopreserved embryos progressed to the blastocyst stage by day 6 . Clinical ly , 7 ( 5.6 % ) of the 125 cycles did not result in a transfer . Blastocyst formation rates ranged from 33%-63 % in the five study groups . Implantation rates ranged from 15%-52 % and pregnancy rates ranged from 37%-75 % . CONCLUSION ( S ) Extended culture to day 5 or 6 results in acceptable blastocyst formation rates , implantation rates , and pregnancy rates The transfer of blastocysts has been associated with a very high implantation rate . However , not all embryos achieve the blastocyst stage . Our study was set up to demonstrate whether embryo morphology on day 3 predicts subsequent blastocyst formation . A prospect i ve study was carried out in 48 patients with a mean of 2.9 failed in-vitro fertilization ( IVF ) attempts . In this new cycle , the morphology of the embryos on day 3 was noted . After pre- selection of the embryos which would have been transferred on day 3 , all embryos were cultured individually and allowed to develop further until transfer on day 5 . The clinical pregnancy rate per transfer was 46 % , and the overall implantation rate was 24 % . When only blastocysts were transferred the pregnancy rate was 53 % with an implantation rate of 30 % . Thirty-nine per cent of all embryos reached the blastocyst stage on day 5 ; 47 % of class 1 and 2 embryos ( good quality ) in contrast to 21 % of class 3 and 4 embryos ( poor quality ) . Respectively 45 % of class 1 and 2 embryos and 69 % of class 3 and 4 embryos arrested in development or degenerated . Only 51 % of the embryos that were transferred on day 5 had been pre-selected for transfer on day 3 . In conclusion , it appears that the predictive value of embryo morphology on day 3 for subsequent blastocyst formation is limited Results of french multiple collaborative studies are reported to evaluate the possible benefits of coculture in human IVF program . Prospect i ve r and omized study of IVF with transfer on day two versus IVF with transfer on day 6 shows that coculture does not improve overall results but leads to a reduction of triple or quadruple pregnancies . When applied to patients with more than 4 failures of embryo transfers on day 2 , delayed transfer of blastocyst results in a high rate of clinical pregnancy ( 39 % ) . Transfers of frozen-thawed blastocysts result in 17.8 % ongoing pregnancies .  Coculture is also a powerful tool for underst and ing early embryo development : when fertilization arises from sperm with poor characteristics or from frozen sperm of donor , embryo development appears to be altered : in these situations , rate of normally developing embryo is reduced and early embryo development becomes independent of fertilization rate BACKGROUND The aim of this study was to compare ongoing pregnancy rates per started cycle between patients r and omized at consultation to have embryo transfer either on day 3 or on day 5 of in-vitro culture . METHODS All patients < 43 years of age for whom IVF was indicated were allowed to participate in the study ( day 3 group , 234 patients ; day 5 group , 226 patients ) . Ovarian stimulation was performed either using GnRH antagonists/recombinant FSH ( rFSH ) ( day 3 , 70.1 % of patients ; day 5 , 72.6 % of patients ) or using the long GnRH agonist protocol /urinary gonadotropins ( day 3 , 29.9 % of patients ; day 5 27.4 % of patients ) . RESULTS The r and om decision to initiate a cycle leading to day 5 as compared with a day 3 transfer was associated with a significantly lower chance of embryo cryopreservation ( day 3 , 61.5 % ; day 5 , 50.4 % ; P<0.02 ) . Ongoing pregnancy rate per started cycle did not differ between the two groups compared [ day 3 , 32.1 % , 95 % confidence interval ( CI ) 26.4 - 38.2 % ; day 5 , 33.2 % , 95 % CI 27.3 - 39.5 % ] . CONCLUSIONS Advising patients at consultation to initiate an IVF cycle leading to a day 5 as compared with a day 3 transfer does not appear to increase the probability of ongoing pregnancy , and is associated with a significantly lower probability of obtaining cryopreserved embryos It is believed that delayed transfer of embryos after IVF allows for a better selection of good quality embryos . Hence , the number of embryos and all other prognostic factors being equal , transfer of day 3 embryos should be associated with higher implantation and pregnancy rates than transfer of day 2 embryos . To investigate this hypothesis , a prospect i ve r and omized study was carried out to compare implantation and pregnancy rates between day 2 and day 3 transfers . The relationship between the embryo quality score of day 2 and day 3 embryos and their respective implantation rates was also analysed . In a 2 year period all patients undergoing infertility treatment and in whom at least seven normally fertilized oocytes were obtained were included in the study . A minimization procedure was performed taking into account the patient 's age and the method of fertilization ( IVF or intracytoplasmic sperm injection ) . By using a uniform policy of embryo transfer , the number of embryos transferred was similar in both groups . The outcome parameters were embryo quality , implantation and pregnancy rates . No difference was observed in implantation and pregnancy rates between transfers on day 2 versus day 3 ( 23.8 versus 23.8 % and 47.9 versus 46.8 % respectively ) . The incidence of embryos of moderate to poor quality was higher in embryos cultured for 3 days compared with those cultured for 2 days . It is concluded that the outcomes of embryo transfer in terms of implantation and pregnancy rates are comparable for day 2 and day 3 embryos , although the overall embryo quality score decreases when embryos are kept in culture till day 3 BACKGROUND It is generally accepted that the age-related increased aneuploidy rate is correlated with reduced implantation and a higher abortion rate . Therefore , advanced maternal age ( AMA ) couples are a good target group to assess the possible benefit of preimplantation genetic diagnosis for aneuploidy screening ( PGD-AS ) on the outcome after assisted reproductive technology ( ART ) . METHODS A prospect i ve r and omized controlled clinical trial ( RCT ) was carried out comparing the outcome after blastocyst transfer combined with PGD-AS using fluorescence in situ hybridization ( FISH ) for the chromosomes X , Y , 13 , 16 , 18 , 21 and 22 in AMA couples ( aged > or = 37 years ) with a control group without PGD-AS .  From the 400 ( 200 for PGD-AS and 200 controls ) couples that were allocated to the trial , an oocyte pick-up was performed effectively in 289 cycles ( 148 PGD-AS cycles and 141 control cycles ) . RESULTS Positive serum HCG rates per transfer and per cycle were the same for PGD-AS and controls : 35.8 % ( 19.6 % ) [ % /per embryo transfer ( per cycle ) ] and 32.2 % ( 27.7 % ) , respectively ( NS ) . Significantly fewer embryos were transferred in the PGD-AS group than in the control group ( P<0.001 ) . The implantation rate ( with fetal heart beat ) was 17.1 % in the PGD-AS group versus 11.5 % in the control group ( not significant ; P=0.09 ) . We observed a normal diploid status in 36.8 % of the embryos . CONCLUSIONS This RCT provides no arguments in favour of PGD-AS for improving clinical outcome per initiated cycle in patients with AMA when there are no restrictions in the number of embryos to be transferred Preliminary results are presented concerning the first clinical application of cocultures of human embryos .  In the experimental group , the embryos were cultured and transferred on day 5 post-insemination .  Blastocyst formation was not dependent upon the stimulation regimen . Long term or ultrashort stimulation of the ovaries after gonadotrophin releasing hormone analogue gave 55 - 60 % blastocyst formation . Serum was not necessary to obtain blastocysts . When the embryos were cocultured , we observed an increase in the implantation rates per embryo in the pregnant patients . However , a real increase in the pregnancy rate per transfer was observed in a population of patients who had had repeated failures of embryo transfer . This observation is discussed as possibly bypassing an effect of uterine motility , but the overall beneficial effect has to be assessed in a double blind r and omized study . It is probable that improvements will not be observed for all the indications for in vitro fertilization OBJECTIVE To analyze the birth weights and sex ratio of infants born after blastocyst transfer .  DESIGN Retrospective analysis . SETTING Three infertility clinics . PATIENT(S ) Patients admitted for IVF with blastocyst transfer .  INTERVENTION None . MAIN OUTCOME MEASURE(S ) Birth weights and sex ratio of infants born after blastocyst transfer .  RESULT ( S ) Statistically significantly more male infants were born after transfer of fresh blastocysts , either cocultured or cultured in sequential media . No specific differences in birth weight were observed between infants born after blastocyst transfer and those born after spontaneous conception . CONCLUSION ( S ) More male infants than female infants were born after blastocyst transfer when transfers were performed as soon as the blastocyst stage was reached and male embryos had a faster cleavage rate BACKGROUND Recently , advances in human  IVF-embryo transfer ( ET ) have been reported using sequential media and blastocyst stage ET . In our previous report , using a prospect i ve , r and omized study , no advantage was found using the blastocyst stage ET compared with day 3 ET . This study was performed in order to evaluate implantation and pregnancy rates of hatching blastocyst stage ET compared with conventional day 3 ET . METHODS AND RESULTS A total of 480 patient cycles were evaluated using a prospect i ve , r and omized study . The pregnancy rate and implantation rate were compared between the day 3 ET ( n = 240 ) and hatching blastocyst stage ET ( Hat ET ; n = 240 ) . The Hat ET group had a pregnancy rate of 29.3 % ( 55 out of 188 ) and an implantation rate of 21.4 % ( 67 out of 313 ) . The day 3 ET group had a pregnancy rate of 29.2 % ( 70 out of 240 ) and an implantation rate of 19.1 % ( 93 out of 488 ) . In the Hat ET group , the pregnancy rate , implantation rate and ongoing pregnancy rate of day 5 ET and day 6 ET were all higher than the respective rates in the day 7 - 9 ET group . CONCLUSION We found that the pregnancy rate and implantation rate of ET with hatching stage blastocysts had no advantage compared with the conventional day 3 ET OBJECTIVE : To evaluate the efficacy of blastocyst transfer in comparison with cleavage stage transfer . STUDY DESIGN : A r and omized , prospect i ve study was conducted in Infertility clinic , Department of Obstetrics and Gynecology , Mahatma G and hi Hospital , Jaipur on 300 patients aged 25 - 40 years undergoing in-vitro fertilization (IVF)/intra-cytoplasmic sperm injection ( ICSI ) cycle from May 2010-April 2011 . When three or more Grade -I embryos were observed on day 2 of culture , patients were divided r and omly into two study groups , cleavage stage transfer and blastocyst transfer group having 150 patients each . Primary outcomes evaluated were , Clinical pregnancy rate and Implantation rate . The results were analyzed using proportions , st and ard deviation and Chi-square test . RESULTS : Both the groups were similar for age , indication and number of embryos transferred . Clinical pregnancies after blastocyst transfer were significantly higher 66 ( 44.0 % ) compared to cleavage stage embryo transfer 44 ( 29.33 % ) ( P < 0.01 ) . Implantation rate for blastocyst transfer group was also significantly higher ( P < 0.001 ) . CONCLUSION : Blastocyst transfer having higher implantation rate and clinical pregnancy rate lead to reduction in multiple pregnancies OBJECTIVE To compare blastocyst-stage embryo 
    Output:
    
There is low quality evidence for live birth and moderate quality evidence for clinical pregnancy that fresh blastocyst stage transfer is associated with higher rates than fresh cleavage stage transfer .
There was no evidence of a difference between the groups in cumulative pregnancy rates derived from fresh and frozen-thawed cycles following a single oocyte retrieval , but the evidence for this outcome was very low quality .
Thus , although there is a benefit favouring blastocyst transfer in fresh cycles , it remains unclear whether the day of transfer impacts on cumulative live birth and pregnancy rates .