Abstract
STUDY QUESTION
Can a generally applicable morphokinetic algorithm suitable for Day 3 transfers of time-lapse monitored embryos originating from different culture conditions and fertilization ...methods be developed for the purpose of supporting the embryologist's decision on which embryo to transfer back to the patient in assisted reproduction?
SUMMARY ANSWER
The algorithm presented here can be used independently of culture conditions and fertilization method and provides predictive power not surpassed by other published algorithms for ranking embryos according to their blastocyst formation potential.
WHAT IS KNOWN ALREADY
Generally applicable algorithms have so far been developed only for predicting blastocyst formation. A number of clinics have reported validated implantation prediction algorithms, which have been developed based on clinic-specific culture conditions and clinical environment. However, a generally applicable embryo evaluation algorithm based on actual implantation outcome has not yet been reported.
STUDY DESIGN, SIZE, DURATION
Retrospective evaluation of data extracted from a database of known implantation data (KID) originating from 3275 embryos transferred on Day 3 conducted in 24 clinics between 2009 and 2014. The data represented different culture conditions (reduced and ambient oxygen with various culture medium strategies) and fertilization methods (IVF, ICSI). The capability to predict blastocyst formation was evaluated on an independent set of morphokinetic data from 11 218 embryos which had been cultured to Day 5.
PARTICIPANTS/MATERIALS, SETTING, METHODS
The algorithm was developed by applying automated recursive partitioning to a large number of annotation types and derived equations, progressing to a five-fold cross-validation test of the complete data set and a validation test of different incubation conditions and fertilization methods. The results were expressed as receiver operating characteristics curves using the area under the curve (AUC) to establish the predictive strength of the algorithm.
MAIN RESULTS AND THE ROLE OF CHANCE
By applying the here developed algorithm (KIDScore), which was based on six annotations (the number of pronuclei equals 2 at the 1-cell stage, time from insemination to pronuclei fading at the 1-cell stage, time from insemination to the 2-cell stage, time from insemination to the 3-cell stage, time from insemination to the 5-cell stage and time from insemination to the 8-cell stage) and ranking the embryos in five groups, the implantation potential of the embryos was predicted with an AUC of 0.650. On Day 3 the KIDScore algorithm was capable of predicting blastocyst development with an AUC of 0.745 and blastocyst quality with an AUC of 0.679. In a comparison of blastocyst prediction including six other published algorithms and KIDScore, only KIDScore and one more algorithm surpassed an algorithm constructed on conventional Alpha/ESHRE consensus timings in terms of predictive power.
LIMITATIONS, REASONS FOR CAUTION
Some morphological assessments were not available and consequently three of the algorithms in the comparison were not used in full and may therefore have been put at a disadvantage. Algorithms based on implantation data from Day 3 embryo transfers require adjustments to be capable of predicting the implantation potential of Day 5 embryo transfers. The current study is restricted by its retrospective nature and absence of live birth information. Prospective Randomized Controlled Trials should be used in future studies to establish the value of time-lapse technology and morphokinetic evaluation.
WIDER IMPLICATIONS OF THE FINDINGS
Algorithms applicable to different culture conditions can be developed if based on large data sets of heterogeneous origin.
STUDY FUNDING/COMPETING INTEREST(S)
This study was funded by Vitrolife A/S, Denmark and Vitrolife AB, Sweden. B.M.P.’s company BMP Analytics is performing consultancy for Vitrolife A/S. M.B. is employed at Vitrolife A/S. M.M.’s company ilabcomm GmbH received honorarium for consultancy from Vitrolife AB. D.K.G. received research support from Vitrolife AB.
The primary purpose of this time-lapse data analysis was to identify the association between the nucleation status of a Day 2 preimplantation embryo and live births following in vitro fertilization ...(IVF). The retrospective data analysis was based on 2769 transferred embryos from 1966 treatment cycles and utilised only Known Implantation Data (KID) for live births. Nucleation errors (NE) such as micronucleation, binucleation, multinucleation and minor error groups, were annotated in the time-lapse images which were taken every 15 minutes for a minimum of 44 hours post insemination. Further, factors that may impact NE and the relationship of early morphological attributes and morphokinetic variables with NE occurrence were explored. The frequency of NE among the transferred embryos was 23.8%. The reversibility of NE evidenced by their presence at the two-cell stage, but absence at the four-cell stage was 89.6%. Embryos exhibiting nucleation errors at the two-cell stage had significantly lower live birth rates compared to embryos with no nucleation errors, constituting a significant predictor. A Generalized Additive Mixed Model was used to control for confounders and for controlling clustering effects from dual embryo transfers. Increased incidences of NE were observed with increasing age, with delayed occurrence of cell divisions and in oocytes inseminated with surgically retrieved spermatozoa. NE assessment and their impact on live birth provides valuable markers for early preimplantation embryo selection. In addition, the high incidence of reversibility of NE and their possible impact on live birth suggest that incorporating two-cell nuclear status annotations in embryo selection, alongside morphology and morphokinetics, is of value.
The purpose of this retrospective time-lapse data analysis from transferred preimplantation human embryos was to identify early morphokinetic cleavage variables that are related to implantation and ...live birth following in vitro fertilization (IVF). All embryos were monitored from fertilization check until embryo transfer for a minimum of 44 hours. The study was designed to assess the association between day 2 embryo morphokinetic variables with implantation and live birth based on Known Implantation Data (KID). The kinetic variables were subjected to quartile-based analysis. The predictive ability for implantation and live birth was studied using receiver operator characteristic (ROC) curves. Three morphokinetic variables, time to 2-cells (t2), duration of second cell cycle (cc2) below one threshold and cc2 above another threshold had the highest predictive value with regards to implantation and live birth following IVF treatment. The predictive pre-transfer information has little divergence between fetal heartbeat and live birth data and therefore, at least for early morphokinetic variables up to the four-cell stage (t4), conclusions and models based on fetal heartbeat data can be expected to be valid for live birth datasets as well. The three above mentioned variables (t2, cc2 below one threshold and cc2 above another threshold) may supplement morphological evaluation in embryo selection and thereby improve the outcome of in vitro fertilization treatments.
Globally, soil carbon sequestration is expected to hold a major potential to mitigate agricultural greenhouse gas emissions. However, the majority of life cycle assessments (LCA) of agricultural ...products have not included possible changes in soil carbon sequestration. In the present study, a method to estimate carbon sequestration to be included in LCA is suggested and applied to two examples where the inclusion of carbon sequestration is especially relevant: 1) Bioenergy: removal of straw from a Danish soil for energy purposes and 2) Organic versus conventional farming: comparative study of soybean production in China. The suggested approach considers the time of the soil CO2 emissions for the LCA by including the Bern Carbon Cycle Model. Time perspectives of 20, 100 and 200 years are used and a soil depth of 0–100 cm is considered. The application of the suggested method showed that the results were comparable to the IPCC 2006 tier 1 approach in a time perspective of 20 year, where after the suggested methodology showed a continued soil carbon change toward a new steady state. The suggested method estimated a carbon sequestration for the first example when storing straw in the soil instead of using it for bioenergy of 54, 97 and 213 kg C t−1 straw C in a 200, 100 and 20 years perspective, respectively. For the conversion from conventional to organic soybean production, a difference of 32, 60 or 143 kg soil C ha−1 yr−1 in a 200, 100 or 20 years perspective, respectively was found. The study indicated that soil carbon changes included in an LCA can constitute a major contribution to the total greenhouse gas emissions per crop unit for plant products. The suggested approach takes into account the temporal aspects of soil carbon changes by combining the degradation and emissions of CO2 from the soil and the following decline in the atmosphere. Furthermore, the results from the present study highlights that the choice of the time perspective has a huge impact on the results used for the LCA. For comparability with the calculation of the global warming potential in LCA, it is suggested to use a time perspective of 100 years when using the suggested approach for soil carbon changes in LCA.
•An approach to include soil carbon changes in LCA of agricultural products is suggested.•The suggested approach takes into account the Bern Carbon Cycle Model.•Soil carbon changes included in LCA can constitute a major contribution for plant products.•Highlights that the choice of time perspective has a huge impact on the results.•It is suggested to use a 100 years perspective for soil carbon changes in LCA.
Organic rules for grazing and access to outdoor areas in pig production may be met in different ways, which express compromises between considerations for animal welfare, feed self-reliance and ...negative environmental impact such as greenhouse gas emissions and nitrate pollution. This article compares the environmental impact of the main organic pig systems in Denmark. Normally, sows are kept in huts on grassland and finishing pigs are raised in stables with access to an outdoor run. One alternative practice is also rearing the fattening pigs on grassland all year round. The third method investigated was a one-unit pen system mainly consisting of a deep litter area under a climate tent and with restricted access to a grazing area. Using life cycle assessment (LCA) methodology, the emissions of greenhouse gases of the free range system were estimated to be 3.3 kg CO
2
-equivalents kg
−1
live weight pig, which was significantly higher than the indoor fattening system and the tent system, yielding 2.9 and 2.8 kg CO
2
-eq. kg
−1
pig, respectively. This was 7–22% higher compared with Danish conventional pig production but, due to the integration of grass-clover in the organic crop rotations these had an estimated net soil carbon sequestration. When carbon sequestration was included in the LCA then the organic systems had lower greenhouse gas emissions compared with conventional pig production. Eutrophication in nitrate equivalents per kg pig was 21–65% higher in the organic pig systems and acidification was 35–45% higher per kg organic pig compared with the conventional system. We conclude that, even though the free range system theoretically has agro-ecological advantages over the indoor fattening system and the tent system due to a larger grass-clover area, this potential is difficult to implement in practice due to problems with leaching on sandy soil. Only if forage can contribute to a larger proportion of the pigfeed uptake may the free range system be economically and environmentally competitive. Improvement of nitrogen cycling and efficiency is the most important factor for reducing the overall environmental load from organic pig meat. Presently, a system with pig fattening in stables and concrete-covered outdoor runs seems to be the best solution from an environmental point of view.
The impact of organic, compared with conventional, farming practices on N leaching loss was studied for Danish mixed dairy and arable farms using an N balance approach based on representative data. ...On mixed dairy farms, a simple N balance method was used to estimate N surplus and N leaching loss. On arable farms, the simple N balance method was unreliable due to changes in the soil N pool. Consequently, the Farm ASSEssment Tool (FASSET) simulation model was used to estimate N surplus, N leaching loss and the changes in the soil N pool. The study found a lower N leaching loss from organic than conventional mixed dairy farms, primarily due to lower N inputs. On organic arable farms, the soil N pool increased over time but the N leaching loss was comparable with conventional arable farms. The soil N pool was increased primarily by organic farming practices and incorporation of straw. The highest increase in the soil N pool was seen on soils with a low initial level of organic matter. The N leaching loss was dependent on soil type, the use of catch crops and the level of soil organic matter, whereas incorporation of straw had a minor effect. N leaching was highest on sandy soils with a high level of soil organic matter and no catch crops. The present results stress the importance of using representative data from organic and conventional farming practices in comparative studies of N leaching loss. Lack of representative data has been a major weakness of previous comparisons on N leaching losses on organic and conventional farms.
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