Abstract
Urban underground space (UUS) can be an effective means to meet the needs of the cities and simultaneously deal with societal and urban challenges. However, in Flanders the use of UUS ...remains to be one of the most forgotten urban assets and is characterised by a haphazard, uncoordinated ‘last resort’ practice detrimental to sustainable development. In a search for new possibilities for qualitative densification the Flemish Government instigated a policy exploration to investigate if efficient use of the UUS could be a possible solution for lowering the daily land take. This paper describes the process and content of the policy exploration and sets out policy recommendations. The paper concludes that although the merits of UUS have been thoroughly recognized and the significance of the subsurface in urban renewal is clear, the efficient use of UUS in Flanders and the fulfilment of Flemish policy objectives cannot be guaranteed without the development of UUS policy and the integration of UUS policy in the overall Flemish urban planning system. The research finds that a clear definition of planning factors for the use of UUS is necessary to support the transition from using the UUS to integration of the UUS into wider urban planning processes. It puts forward the need for a comprehensive list of planning factors, gathered in a holistic, integrated manner, necessary to transition from UUS projects to UUS planning.
STUDY QUESTION
Is the live birth rate (LBR) per embryo thawed/warmed higher when Day 3 cleavage stage embryos are cryopreserved by vitrification compared with slow freezing?
SUMMARY ANSWER
The LBR ...per embryo thawed/warmed was higher after vitrification than after slow freezing on Day 3, based on better embryo survival, quality and availability of embryos in the vitrification group.
WHAT IS KNOWN ALREADY
Post-thawing survival rate of cleavage-stage embryos has been reported to be higher after vitrification than after slow freezing.
STUDY DESIGN, SIZE, DURATION
This RCT was performed in an academic tertiary center between September 2011 and March 2013. If supernumerary embryos were available on Day 3, patients were randomized at the time of cryopreservation using a computerized system to determine a simple allocation to the vitrification group or the slow freezing group and all embryos were frozen with the same technique. The primary outcome of this study was the LBR per embryo thawed/warmed. Power calculation revealed that 184 thawed embryos were needed in each group (β = 0.8, α < 0.05) to test the hypothesis that the LBR per embryo thawed/warmed was significantly higher (16%) after vitrification than after slow freezing (6%).
PARTICIPANTS/MATERIALS, SETTING, METHODS
Patients <40 years old undergoing their first oocyte retrieval (OR), with embryo transfer and with supernumerary embryos on Day 3, were randomized. Day 3 embryos with ≥6 cells, <25% fragmentation and morphologically equal blastomeres were cryopreserved by slow freezing (using 1,2-propanediol and 0.1 M sucrose as cryoprotectant) or by closed vitrification using commercially available freezing/vitrification media. Survival was defined as ≥50% cells were intact after thawing. Thawed embryos were further cultured overnight. In total, 307 patients were randomized to slow freezing (155 patients, 480 embryos) or vitrification (152 patients, 495 embryos).
MAIN RESULTS AND THE ROLE OF CHANCE
By March 2013, 200 embryos were thawed after slow freezing in 95 cycles for 79 patients and 217 embryos were warmed after vitrification in 121 cycles in 90 patients. The LBR per embryo thawed/warmed was significantly higher after vitrification (16.1% (35/217)) than after slow freezing (5.0% (10/200); P < 0.0022; relative risk (RR) 3.23; 95% confidence interval (CI) 1.64–6.35). Similarly, the implantation rate per embryo thawed/warmed was higher after vitrification (20.7% (45/217) than after slow freezing (7.5% (15/200); P = 0.0012; RR 2.76; CI 1.59–4.81). The survival rate was significantly higher after vitrification (84.3% (183/217) than after slow freezing (52.5% (105/200); P < 0.0001). Significantly more embryos were fully intact after vitrification (75.4% (138/183) than after slow freezing (28.6% (30/105); P < 0.0001). The number of transfers was significantly higher after vitrification (90.1% (109/121)) than after slow freezing (73.7% (70/95); P = 0.0024).
LIMITATIONS, REASONS FOR CAUTION
Survival rates in the slow freezing group were low in this study. Additional RCTs are needed to compare reproductive outcome after vitrification and after slow freezing with 1,2-propanediol and 0.2 M sucrose, since this method has been reported to have better survival than the method used in our study. Our findings are only applicable to the specific slow freezing cryopreservation medium used in our study, and not to any other commercially available media.
WIDER IMPLICATIONS OF THE FINDINGS
When compared with slow freezing using 1,2-propanediol and 0.1 M sucrose as cryoprotectant, vitrification of Day 3 cleavage stage embryos resulted in a higher LBR per embryo warmed, and may therefore result into a higher cumulative delivery rate after one oocyte retrieval.
STUDY FUNDING/COMPETING INTEREST(S)
None.
TRIAL REGISTRATION NUMBER
NCT02013024.
Abstract
STUDY QUESTION
Does ultra-long downregulation with a GnRH agonist (triptorelin depot) in previously operated patients with endometriosis improve the rate of clinical pregnancy with positive ...fetal heart beat (CPHB) in the subsequent initiated fresh ART cycle?
SUMMARY ANSWER
Ultra-long downregulation with a GnRH agonist prior to ART did not improve the rate of CPHB in the subsequent fresh ART cycle in previously completely operated patients but the trial was underpowered due to early termination.
WHAT IS KNOWN ALREADY
Administration of GnRH agonists for a period of 3–6 months prior to ART in women with endometriosis may increase the odds of clinical pregnancy. However, the quality of the studies on which this statement is based is questionable, so these findings need confirmation.
STUDY DESIGN, SIZE, DURATION
A controlled, randomized, open label trial was performed between 1 June 2013 and 31 December 2016 (start and end of recruitment, respectively). Patients with prior complete laparoscopic treatment of any type or stage of endometriosis and an indication for ART were randomized (by a computer-generated allocation sequence) into two groups: the control group underwent ART stimulation in a classical long agonist protocol using preparation with oral contraceptives, the ultra-long group first underwent at least 3 months downregulation followed by a long agonist protocol for ART stimulation. The sample size was calculated to detect a superiority of the ultra-long downregulation protocol, based on the hypothesis that baseline CPHB rate in the control group of 20% would increase to 40% in the ultra-long group. For a power of 20% at a significance level of 5%, based on two-sided testing, including 5% of patients lost to follow-up, the necessary sample size was 172 patients (86 per group).
PARTICIPANTS/MATERIALS, SETTING, METHODS
This trial was conducted at the Leuven University Fertility Center, a tertiary care center for endometriosis and infertility, and a total of 42 patients were randomized (21 in the control group and 21 in the ultra-long group).
MAIN RESULTS AND THE ROLE OF CHANCE
Baseline characteristics were similar in both groups. The primary outcome studied—CPHB after the initiated ART treatment—did not differ and was 25% (5/20) in the control group, and 20% (4/20) in the ultra-long group (P > 0.999; relative risk (RR) 1.25, 95% CI 0.41–3.88). Cumulative (fresh + associated frozen) CPHB rates were also similar in the control versus ultra-long group (8/20, 40% vs 6/20, 30%, P = 0.7411; RR = 1.33, 95% CI 0.57–3.19). When other secondary outcomes were compared with the ultra-long group, patients from the control group had a shorter duration of stimulation (mean 11.8 days (SD ± 2.4) versus 13.2 days (SD ± 1.5), P = 0.0373), a lower total dose of gonadotrophins used (mean 1793 IU/d (SD ± 787) vs 2329 (SD ± 680), P = 0.0154), and a higher serum estradiol concentration (ng/ml) at the end of ovarian stimulation on the day of ovulation triggering or cycle cancellation (mean1971 (SD ± 1495) vs 929 (± 548); P = 0.0326), suggesting a better ovarian response in the control group.
LIMITATIONS, REASONS FOR CAUTION
Due to a strong patient preference, nearly exclusively against ultra-long downregulation (even though patients were thoroughly informed of the potential benefits), the targeted sample size could not be achieved and the trial was stopped prematurely.
WIDER IMPLICATIONS OF THE FINDINGS
Conditional power analysis revealed that the probability of confirming the study hypothesis if the study were completed would be low. We hypothesize that in patients with prior complete surgical treatment of endometriosis, the ultra-long protocol does not enhance ART-CPHB rates. Patient’s concerns and preferences regarding possible side-effects, and delay of ART treatment start with the ultra-long protocol should be taken into account when considering this type of treatment in women with endometriosis.
STUDY FUNDING/COMPETING INTEREST(S)
C.T. was during 2 years funded by a grant from the Clinical research Foundation of UZ Leuven (KOF) and during 2 years by the Research Foundation—Flanders (FWO grant number: 1700816N). C.T. reports grants from Clinical Research Foundation of the University Hospitals of Leuven (KOF), grants from Fund for Scientific Research Flanders (FWO), during the conduct of the study; grants, non-financial support and other from Merck SA, non-financial support and other from Gedeon Richter, non-financial support from Ferring Pharmaceuticals, outside the submitted work. T.D. is vice president and head of Global Medical Affairs Fertility, Research and Development, Merck KGaA, Darmstadt, Germany. He is also a professor in Reproductive Medicine and Biology at the Department of Development and Regeneration, Group Biomedical Sciences, KU Leuven (University of Leuven), Belgium and an adjunct professor at the Department of Obstetrics and Gynecology in the University of Yale, New Haven, USA. Neither his corporate role nor his academic roles represent a conflict of interest with respect to the work done by him for this study. A.C. reports personal fees from Merck S.p.A., outside the submitted work. The other co-authors have no conflict of interest.
TRIAL REGISTRATION NUMBER
UZ Leuven trial registry SS55300, EudraCT number 2013-000993-32, clinicaltrials.gov NCT02400801.
TRIAL REGISTRATION DATE
Registration for EudraCT on 1 March 2013.
DATE OF FIRST PATIENT’S ENROLMENT
4 September 2013.
Are cumulative pregnancy rates better if supernumerary embryos are vitrified on Day 5/6 instead of Day 3?
The results do not show a significant difference in cumulative pregnancy rates between the ...Day 3 and Day 5/6 vitrification groups.
Pregnancy and live birth rates following IVF or ICSI treatment are higher after extended embryo culture and blastocyst transfer (Day 5/6) compared to cleavage-stage (Day 3) transfer. Cumulative pregnancy rates from one oocyte retrieval (OR) cycle show no significant difference after fresh and frozen embryo transfers, but only one study has used vitrification for the cryopreservation of supernumerary embryos while four studies have used a slow freezing protocol.
Our prospective randomized controlled trial was performed in an academic centre between January 2018 and August 2020. Patients were randomized into vitrification Day 3 (n = 80) or Day 5/6 (n = 81) groups. The primary outcome was the cumulative ongoing pregnancy rate (cOPR), considering only the first pregnancy for each couple. The power calculation revealed that 75 patients were required in each group, when assuming a 50% cOPR with four embryo transfers in the vitrification Day 3 group vs two transfers in the vitrification Day 5/6 group.
Patients <38 years undergoing their first or second OR cycles were randomized at the start of the first cycle. Up to two cycles were included in the analysis. A fresh embryo transfer was performed on Day 3. Supernumerary embryos (with ≥6 cells, <25% fragmentation, and equal blastomeres) or blastocysts (with expansion grade ≥2 with inner cell mass and trophectoderm score A/B) were vitrified on Day 3 or Day 5/6, respectively, and then transferred at a later date. A time-to-event analysis was performed with the patient's first ongoing pregnancy as the event of interest and the number of embryo transfers as the time component. The statistical comparison was performed by a Cox proportional hazards model. Cumulative costs of vitrification on Day 3 vs Day 5/6 were explored and compared using Mann-Whitney U tests.
By December 2021, 233 transfers (96 fresh and 137 frozen) in 77 patients were performed in the vitrification Day 3 group and 201 transfers (88 fresh and 113 frozen) in 77 patients were performed in the vitrification Day 5/6 group. The time-to-event analysis did not show a difference between the two arms with regard to the patient's first ongoing pregnancy as the primary study outcome (hazard ratio HR 1.25, 95% CI 0.82; 1.92, P = 0.30). The cumulative ongoing pregnancy rate after eight transfers (from one or two ORs) was 57% in the vitrification Day 3 group vs 58% in the vitrification Day 5/6 group. The median number of embryo transfers until a pregnancy was achieved was five vs four, respectively, in the vitrification Day 3 group vs the Day 5/6 group. Similar results were found for the secondary study outcome, i.e. clinical pregnancy with foetal heart rate (HR 1.19, 95% CI 0.78; 1.80, P = 0.41). The cumulative clinical pregnancy rate (cCPR) after eight embryo transfers was 62% in the vitrification Day 3 group vs 59% in the vitrification Day 5/6 group. The median number of transfers until a pregnancy was achieved was four in both groups. The healthcare consumption pattern differed between the two groups and we observed higher costs for the vitrification Day 3 group compared to the vitrification Day 5/6 group, although these differences were not statistically significant.
Although our power calculation revealed that only 75 patients were needed in each study group (β = 0.87, α < 0.05), the numbers were low. Also, different numbers of single and double embryo transfers were performed between the two groups, which may have affected the results. The cost analysis was performed on a subset of the patients and is therefore exploratory.
Our study shows no difference in the cumulative pregnancy rate nor costs after fresh and frozen embryo transfers of at most two sequential OR cycles between the Day 3 and Day 5/6 vitrification groups; however, obstetric and perinatal outcomes should be taken into account to determine the best strategy.
This study was funded as an investigator-sponsored study of S.D. by Merck nv/sa Belgium, an affiliate of Merck KGaA, Darmstadt, Germany, and by Gedeon Richter Benelux (PA18-0162). The authors declare no conflict of interest related to this study.
NCT04196036.
15 January 2018.
15 January 2018.
STUDY QUESTION
Is there a link between morphometric characteristics measured by a computer-assisted scoring system and clinical pregnancy outcome?
SUMMARY ANSWER
The results confirm that ...computer-assisted assessment of the total embryo volume is associated with clinical pregnancy outcome and can be used to complement current procedures of embryo selection.
WHAT IS KNOWN ALREADY
Morphometric analysis of a large group of embryos has revealed the potential to optimize algorithms for image-analysis systems for the grading of embryos and predicting pregnancy outcomes.
STUDY DESIGN, SIZE, DURATION
Oocytes and embryos were obtained from 458 patients who underwent single embryo transfer on Day 3 after IVF/ICSI, between September 2006 and December 2010 at the Leuven University Fertility Center, Belgium. In total, the data set contained 2796 embryos including 458 embryos that were transferred on Day 3. Ongoing pregnancy was defined as the presence of at least one intrauterine gestational sac at 20 weeks.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Patients included in this study were younger than 36 years, entering their first (n = 375) or second (n = 83) IVF/ICSI cycle and were only included once. Patients were excluded if the cycle included biopsy for PGD or if donor sperm/donor oocytes were used. Based on the 26 sequential images of the same embryo taken at one time point in different planes, the software calculates the total cytoplasmic volume for each time point, from which any reduction or change in the volume with time can be assessed (which helps interpret the degree of fragmentation) and the size of blastomeres. The diameter of the smallest and largest blastomere and the total volume of each embryo were extracted from the computer-assisted scoring system database and the coefficient of diversity was calculated for Days 1, 2 and 3. A logistic regression analysis was performed to determine the range of embryo volume associated with an increased chance of pregnancy.
MAIN RESULTS AND THE ROLE OF CHANCE
On Day 3, blastomeres of 8-cell stage embryos were less divergent in size than those of 6-, 7-, 9-cell stage embryos. Although, the coefficients of diversity (ratio of the largest:smallest blastomeres) of implanted embryos tended to be lower than for non-implanted embryos, the difference was only significant for 6-cell stage embryos (P = 0.02). After logistic regression, an association between total embryo volume and pregnancy was observed which had a quadratic nature: both lower and higher volumes were associated with a lower probability of successful pregnancy. A significant association was identified between total embryo volume and pregnancy rate on both Days 2 (P = 0.003) and 3 (P = 0.0003). Diagnostic measures (sensitivity, specificity, positive predictive value, accuracy and c-statistics) of the defined volume range were relatively poor. However, results showed a good negative predictive value 76.86% (95% confidence interval 71.03–82.02) on Day 3.
LIMITATIONS, REASONS FOR CAUTION
A general disadvantage of studies evaluating the impact of a characteristic on the implantation potential of an embryo is the fact that the best embryo is chosen for transfer. No comparisons can therefore be made with the other embryos. Moreover, the decision process is currently based on a non-automated, standard scoring system, which means that a ‘bias’ in the selection process is always present.
WIDER IMPLICATIONS OF THE FINDINGS
Our results are an important step towards the development of an automated computer-assisted scoring system for the morphological characteristics of human embryos to improve embryo selection for optimizing implantation potential. Total embryo volume appears to be one of the objective characteristics that should be included.
STUDY FUNDING/COMPETING INTEREST(S)
None.
TRIAL REGISTRATION NUMBER
Not applicable.
Patients carrying a chromosomal rearrangement (CR) have an increased risk for chromosomally unbalanced conceptions. Preimplantation genetic diagnosis (PGD) may avoid the transfer of embryos carrying ...unbalanced rearrangements, therefore increasing the chance of pregnancy. Only 7–12 loci can be screened by fluorescence in situ hybridization whereas microarray technology can detect genome-wide imbalances at the single cell level. We performed PGD for a CR carrier with karyotype 46,XY,ins(3;2)(p23;q23q14.2),t(6;14)(p12.2;q13) using array comparative genomic hybridization. Selection of embryos for transfer was only based on copy number status of the chromosomes involved in both rearrangements. In two ICSI–PGD cycles, nine and seven embryos were analysed by array, leaving three and one embryo(s) suitable for transfer, respectively. The sensitivity and specificity of single cell arrays was 100 and 88.8%, respectively. In both cycles a single embryo was transferred, resulting in pregnancy following the second cycle. The embryo giving rise to the pregnancy was normal/balanced for the insertion and translocation but carried a trisomy 8 and nullisomy 9 in one of the two biopsied blastomeres. After 7 weeks of pregnancy the couple miscarried. Genetic analysis following hystero-embryoscopy showed a diploid (90%)/tetraploid (10%) mosaic chorion, while the gestational sac was empty. No chromosome 8 aneuploidy was detected in the chorion, while 8% of the cells carried a monosomy for chromosome 9. In summary, we demonstrate the feasibility and determine the accuracy of single cell array technology to test against transmission of the unbalanced meiotic products that can derive from CRs. Our findings also demonstrate that the genomic constitution of extra-embryonic tissue cannot necessarily be predicted from the copy number status of a single blastomere.
STUDY QUESTION
What is the impact of the Belgian legislation (1 July 2003), coupling reimbursement of six assisted reproduction technology (ART) cycles per patient to restricted embryo transfer ...policy, on cumulative delivery rate (CDR) per patient?
SUMMARY ANSWER
The introduction of Belgian legislation in ART had no negative impact on the CDR per patient based on realistic estimates within six cycles or 36 months.
WHAT IS KNOWN ALREADY
The introduction of Belgian legislation limiting the number of embryos for transfer resulted in a reduction of the multiple pregnancy rate (MPR) per cycle by 50%.
STUDY DESIGN, SIZE, DURATION
A retrospective cohort study with a study group after implementation of the new ART legislation (July 2003 to June 2006) and the control group, before legislation (July 1999 to June 2002).
PARTICIPANTS/MATERIALS, SETTING, METHODS
CDR was compared in an academic tertiary setting between a study group after legislation (n = 795 patients, 1927 fresh and 383 frozen-thawed embryo transfer (FET) cycles) and a control group before legislation (n = 463 patients, 876 fresh and 185 FET cycles) within six cycles or 36 months, delivery or discontinuation of treatment. The CDR was estimated using life table analysis considering pessimistic, optimistic and realistic scenarios and compared after adjustment for confounding variables. In the realistic scenario we included information on embryo quality to define the prognosis of each patient discontinuing treatment.
MAIN RESULTS AND THE ROLE OF CHANCE
In the realistic scenario, CDR within 36 months was comparable (all ages, P = 0.221) in study group (60.8%) and control group (65.6%), as well as in different age groups (<36 years, P = 0.242; 36–39 years, P = 0.851; 40–42 years, P = 0.840). In the realistic scenario applied to six cycles, we found lower CDRs in the study group than in the control group within the two first cycles (all ages, P = 0.009; <36 years, P = 0.007) but no difference in CDRs between the two groups within the four subsequent cycles (all ages P = 0.232; <36 years, P = 0.198). The CDR within six cycles was 60 and 65.3% for study group and control group, respectively, for all ages, and 65.8 and 70.4%, respectively, in the subgroup younger than 36 years. In women ≥36 years, CDR within six cycles was comparable in both groups (36–39 years, 43% in study versus 44.4% in control group, P = 0.730; 40–42 years, 21% in study versus 23% in control group, P = 0.786).
LIMITATIONS, REASONS FOR CAUTION
A retrospective cohort study design was the only way to study the impact of legislation on CDR. Owing to the retrospective nature of this analysis over a long period of time, our data are potentially influenced by improvements in techniques and therefore improved success rates in ART over time.
WIDER IMPLICATIONS OF THE FINDINGS
This ‘Belgian model’ can now be considered for application worldwide in countries with the aim to reduce the main ART side effect (high MPR) and its associated costs without a negative effect on the main intended effect (high CDR).
STUDY FUNDING/COMPETING INTEREST(S)
The authors have no conflict of interest to declare. No funding was obtained for this study.
Preimplantation genetic screening is being scrutinized, as recent randomized clinical trials failed to observe the expected significant increase in live birth rates following fluorescence in situ ...hybridization (FISH)-based screening. Although these randomized clinical trials are criticized on their design, skills or premature stop, it is generally believed that well-designed and well-executed randomized clinical trials would resolve the debate about the potential benefit of preimplantation genetic screening. Since FISH can analyze only a limited number of chromosomal loci, some of the embryos transferred might be diagnosed as ‘normal’ but in fact be aneuploid for one or more chromosomes not tested. Hence, genome-wide array comparative genome hybridization screening enabling aneuploidy detection of all chromosomes was thought to be a first step toward a better design. We recently showed array screening indeed enables accurate determination of the copy number state of all chromosomes in a single cell. Surprisingly, however, this genome-wide array screening revealed a much higher frequency and complexity of chromosomal aberrations in early embryos than anticipated, with imbalances in a staggering 90% of all embryos. The mitotic error rate in cleavage stage embryos was proven to be higher than the meiotic aneuploidy rate and as a consequence, the genome of a single blastomere is not representative for the genome of the other cells of the embryo. Hence, potentially viable embryos will be discarded upon screening a single blastomere. This observation provides a biological basis for the failure of the randomized clinical trials to increase baby-take-home rates using FISH on cleavage stage embroys.
BACKGROUND
Freezing/vitrifying and thawing/warming of embryos may impair the successful hatching process of the embryo out of its zona pellucida (ZP) and its following implantation into the uterus. ...Theoretically, assisted hatching (AH) may facilitate the hatching process and subsequently increase implantation rates (IRs).
METHODS
In this prospective randomized controlled trial (RCT), the hypothesis was tested that the IR per embryo transferred is higher after transfer (ET) of frozen/vitrified-thawed/warmed embryos with thinned ZP after AH by modified quarter laser-assisted zona thinning (mQLAZT) when compared with ET of frozen/vitrified-thawed/warmed embryos without mQLAZT. Patients with frozen/vitrified embryos were randomized at the time of thawing/warming to a study group (with mQLAZT) or a control group (without mQLAZT). After thawing/warming, embryos were kept in culture for 24h, and mQLAZT was performed prior to ET.
RESULTS
A total of 647 thawing cycles were randomized to either the mQLAZT group (n = 324) or the control group (n = 323). Reproductive outcome data were available for 302 cycles in the mQLAZT group and 317 cycles in the control group. Transfer could be performed in 73.5% and in 71.9% of the thawing/warming cycles in the mQLAZT group and the control group (P = 0.78), respectively. No significant differences were observed between the mQLAZT group and the control group for the IR 13.3%; 15.6%; rate ratio 0.85; 95% confidence interval (CI), 0.596–1.224, the ongoing IR (10.5 and 13.5%, P = 0.25) and the live birth rate 10.5%;13.3%; rate ratio 0.79; (95% CI), 0.530–1.189 per embryo transferred.
CONCLUSIONS
In this RCT, mQLAZT did not improve the IR per embryo transferred in frozen/vitrified-thawed/warmed embryo transfer cycles.
ClinicalTrials.govID NCT00593775.
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