***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 efficiency of using a continuous ( one-step ) protocol with a single medium for the culture of human embryos in a time-lapse incubator ( TLI ) . DESIGN Prospect i ve cohort study on sibling donor oocytes . SETTING University-affiliated in vitro fertilization ( IVF ) center . PATIENT(S ) Embryos from 59 patients . INTERVENTION(S ) Culture in a TLI in a single medium with or without renewal of the medium on day-3 . MAIN OUTCOME MEASURE(S ) Embryo morphology and morphokinetic parameters , clinical pregnancy , take-home baby rate , and perinatal outcomes . RESULT ( S ) The blastocyst rates ( 68.3 vs. 66.8 % ) and the proportion of good- quality blastocysts ( transferred plus frozen ) obtained with the two-step ( 80.0 % ) protocol were statistically significantly similar to those obtained in the one-step protocol ( 72.2 % ) . Similarly , morphokinetic events from early cleavage until late blastocyst stages were statistically significantly equivalent between both groups . No differences were found either in clinical pregnancy rates when comparing pure transfers performed with embryos selected from the two-step ( 75.0 % ) , one-step ( 70.0 % , respectively ) , and mixed ( 57.1 % ) groups . A total of 55 out of 91 embryos transferred implanted successfully ( 60.4 % ) , result ing in a total of 37 newborns with a comparable birth weight mean among groups . CONCLUSION ( S ) Our findings support the idea that in a TLI with a controlled air purification system , human embryos can be successfully cultured continuously from day 0 onward in single medium with no need to renew it on day-3 . This strategy does not affect embryo morphokinetics or development to term and offers more stable culture conditions for embryos as well as practical advantages and reduced costs for the IVF laboratory Background The success of in vitro fertilization techniques is defined by multiple factors including embryo culture conditions , related to the composition of the culture medium . In view of the lack of solid scientific data and in view of the current general belief that sequential media are superior to single media , the aim of this r and omized study was to compare the embryo quality in two types of culture media . Methods In this study , the embryo quality on day 3 was measured as primary outcome . In total , 147 patients younger than 36 years treated with IVF/ICSI during the first or second cycle were included in this study . Embryos were r and omly cultured in a sequential ( group A ) or a single medium ( group B ) to compare the embryo quality on day 1 , day 2 and day 3 . The embryo quality was compared in both groups using a Chi-square test with a significance level of 0.05 . Results At day 1 , the percentage of embryos with a cytoplasmic halo was higher in group B ( 46 % ) than in group A ( 32 % ) . At day 2 , number of blastomeres , degree of fragmentation and the percentage of unequally sized blastomeres were higher in group B than in group A. At day 3 , a higher percentage of embryos had a higher number of blastomeres and unequally sized blastomeres in group B. The number of good quality embryos ( GQE ) was comparable in both groups . The embryo utilization rate was higher in group B ( 56 % ) compared to group A ( 49 % ) . Conclusions Although , no significant difference in the number of GQE was found in both media , the utilization rate was significantly higher when the embryos were cultured in the single medium compared to the sequential medium . The results of this study have a possible positive effect on the cumulative cryo-augmented pregnancy rate . Trial registration STUDY QUESTION Is post-natal growth during the first 2 years of life in IVF singletons affected by type of medium used for culturing human embryos during an IVF treatment ? SUMMARY ANSWER The in vitro culture of human embryos in medium from Cook result ed in singletons with a lower weight during the first 2 years of life compared with singletons born after embryo culture in medium from Vitrolife . WHAT IS KNOWN ALREADY In a previous study , we reported that type of medium used for culturing human IVF embryos during the first few days after fertilization until fresh embryo transfer significantly affects fetal growth and consequently birthweight of the result ing singletons . STUDY DESIGN , SIZE , DURATION From July 2003 to December 2006 , a total of 1432 IVF treatment cycles with fresh embryo transfer were r and omly allocated to have all embryos cultured in medium from Vitrolife AB ( n = 715 ) or from Cook ( n = 717 ) . Two years after delivery , question naires were sent to the parents of all children requesting data about weight , height and head circumference around 1 , 2 , 3 , 4 , 6 , 7.5 , 9 , 11 , 14 , 18 and 24 months of age . These measurements were collected as part of the children 's health programme at municipal infant welfare centres in the Netherl and s by health professionals unaware of this study . PARTICIPANTS / MATERIAL S , SETTING , METHODS Patients requiring donor oocytes or applying for PGD were excluded from the study . From the 294 live born singletons that fulfilled our inclusion criteria , 29 were lost to follow-up . The remaining 265 singletons ( Cook group : 117 , Vitrolife group : 148 ) were included in the analysis . Data analysis included linear regression , to compare cross-sectionally weight st and ard deviation score ( SDS ) , height SDS and head circumference , and the first order Berkey-Reed model for a longitudinal analysis of the growth data . MAIN RESULTS AND THE ROLE OF CHANCE Singletons in the Vitrolife group were heavier during the first 2 years of life compared with singletons in the Cook group . Cross-sectional analyses showed that adjusted weight SDS differed between groups at 1 ( 0.35 ± 0.14 , P = 0.010 ) , 2 ( 0.39 ± 0.14 , P = 0.006 ) , 3 ( 0.35 ± 0.14 , P = 0.011 ) , 4 ( 0.30 ± 0.13 , P = 0.020 ) , 11 ( 0.28 ± 0.13 , P = 0.036 ) , 14 ( 0.32 ± 0.13 , P = 0.014 ) and 24 ( 0.39 ± 0.15 , P = 0.011 ) months of age , while adjusted height SDS was only significantly different at 1 ( 0.21 ± 0.11 , P = 0.048 ) month of age . Head circumference was similar between the two groups at all ages . Longitudinal analyses showed that both post-natal weight ( P = 0.005 ) and height ( P = 0.031 ) differed between the groups throughout the first 2 years of life , while the growth velocity was not significantly different between the two groups . LIMITATIONS , REASONS FOR CAUTION Factors that might influence post-natal growth were included in the analysis ; however , it was not possible to include all such factors , for example childhood diseases or nutrition , as this information was not available . WIDER IMPLICATION S OF THE FINDINGS The effect of culture medium during the first few days after fertilization on prenatal growth and birthweight persists during the first 2 years of life . This suggests that the human embryo is sensitive to its very early environment , and that the culture medium used in IVF may have lasting consequences . Further monitoring of the long-term growth , development and health of IVF children is therefore warranted . STUDY FUNDING /COMPETING INTEREST(S ) W.V. was funded with an unrestricted research grant from the Stichting Fertility Foundation . The authors declare no conflict of interest . TRIAL REGISTRATION NUMBER Not applicable OBJECTIVE To determine whether sequential or monophasic media is the more optimal formulation for blastocyst development and sustained implantation rates ( SIR ) in IVF . DESIGN Paired r and omized controlled trials . SETTING Academic . PATIENT(S ) Infertile couples ( N = 192 ) with female partner ≤42 years old and normal ovarian reserve . INTERVENTION(S ) Fertilized zygotes from each patient were r and omly divided into two groups : [ 1 ] cultured in sequential media and [ 2 ] cultured in monophasic medium . Sequential media consisted of Quinn 's Advantage Cleavage Medium ( SAGE ) followed by Blast Assist ( Origio ) . The monophasic medium used was Continuous Single Culture ( Irvine Scientific ) . Paired ETs were accomplished by transferring the best euploid blastocyst from each media group . DNA fingerprinting was used to link outcomes . MAIN OUTCOME MEASURE(S ) The primary outcome measure was the proportion of blastocysts suitable for clinical use . Secondary outcome measures included timing of blastulation , aneuploidy rates , and SIR . Sustained implantation rate is defined as the number fetal heart beats at 8 - 9 weeks of gestation , divided by the number of embryos transferred . RESULT ( S ) A total of 192 patients had their 2PN embryos ( N = 2,257 ) r and omized to each culture system . Sequential media had higher blastulation rate than monophasic medium ( 55.2 % vs. 46.9 % ) . No differences were found in the day of blastulation or aneuploidy rate . Of the 168 patients who had euploid blastocysts suitable for transfer , 126 completed a paired ET . Among the double ETs , there was no difference in implantation between groups . CONCLUSION ( S ) This is the first r and omized controlled trial to examine paired euploid transfers of sibling zygotes cultured in sequential versus monophasic media . This study demonstrates that the usable blastocyst rate is greatest after culture in the sequential media tested in comparison with the monophasic formulation selected for study . However , no difference exists in timing of blastulation , aneuploidy , or SIR . Whether these observations are generalizable to other media systems remains to be determined . CLINICAL TRIAL REGISTRATION NUMBER NCT01917240 BACKGROUND Extending the period of in-vitro culture to the blastocyst stage may improve implantation rates in IVF treatment . Recognition of the dynamic nature of early embryo metabolism has led to the development of commercially available sequential culture systems . However , their improved efficacy over monoculture systems remains to be demonstrated in prospect i ve studies . METHODS Embryos obtained from 158 women undergoing IVF treatment were r and omized by sealed envelopes to culture in one of three systems : ( A ) culture for 5 days in our own monoculture medium ( Rotterdam medium ) ; ( B ) culture for 3 days in Rotterdam medium followed by 2 days in fresh Rotterdam medium ; ( C ) culture for 5 days using the commercially available G1/G2 sequential culture system . RESULTS There were no significant differences in blastulation , implantation or pregnancy rates between the three tested culture systems . CONCLUSION The employed monoculture system is as effective as the G1/G2 sequential system for the culture of blastocysts for IVF Pregnancies following human blastocyst transfers were established using a protein supplemented modified potassium simplex optimized medium containing amino acids ( KSOM(AA ) ) . Zygotes were first cultured for 2 days in protein supplemented human tubal fluid medium . Result ing embryos ( day 3 ) were subsequently cultured in protein supplemented KSOM(AA ) until day 5 of development . Pregnancy and implantation rates were noted after culture and transfer of blastocysts following this culture scheme . The impact of conventional insemination , intracytoplasmic sperm injection ( ICSI ) and maternal age on developmental rates as well as pregnancy rates was also evaluated . Maternal age had a significant impact ( P < 0.05 ) on developmental rates of embryos until day 3 of culture . Overall , rate of blastocyst development for cultured day 3 embryos was 62 % . Patients > 39 years of age had lower ( P < 0.05 ) rates of blastocyst development than patients in the younger subgroups . ICSI had no impact on developmental rates until day 3 of culture or rate of blastocyst development . Ongoing pregnancy and implantation rates following culture in KSOM(AA ) were 51 and 37 % respectively . These results indicate that KSOM(AA ) supports high rate blastocyst development and result ing pregnancy rates Objective To compare the dynamics of early development between embryos cultured in single and sequential media . Design R and omized , comparative study . Setting Private IVF centre . Patients A total of 446 metaphase II oocytes from 51 couples who underwent oocyte retrieval procedure for intracytoplasmic sperm injection . Forty-nine result ed in embryo transfer . InterventionOocytes were split between single and sequential media produced by the same manufacturer and cultured in a time-lapse incubator . Main outcome measures Morphokinetic parameters until the embryos reached the 5-cell stage ( t5 ) , utilization , clinical pregnancy and implantation rates . Results Embryos cultured in single media were advanced from the first mitosis cycle and reached 2- to 5-cell stages earlier . There was not any difference between the duration s for cell cycle two ( cc2 = t3-t2 ) and s2 ( t4-t3 ) . The utilization , clinical pregnancy and implantation rates did not differ between groups . The proportion of cry 
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Conclusions Although using a single medium for extended culture has some practical advantages and blastocyst formation rates appear to be higher , there is insufficient evidence to recommend either sequential or single-step media as being superior for the culture of embryos to days 5/6 .