This document summarizes a study that assessed the correlation between day 5 and day 6 blastocyst morphology and ploidy status using next-generation sequencing. The study found that slower developing blastocysts biopsied on day 6, but at the same morphological stage as day 5 blastocysts, did not have a similar chromosomal status and provided a lower chance of achieving pregnancy. Specifically, the study analyzed 168 blastocysts biopsied on either day 5 or day 6 that underwent trophectoderm biopsy and next-generation sequencing. It found that day 5 blastocysts had a higher euploidy rate than day 6 blastocysts of the same morphological stage.

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The frequency of aneuploidy status of Day 5 and Day 6
blastocysts assessed by next-generation sequencing technology
(NGS) application.
Jonna Liss1,2, Anna Bruszczynska1, Sebastian Pukszta1, Krzysztof Łukaszuk1,2,3
1INVICTA, Fertility and Reproductive Centre, Gdansk, Poland
2 INVICTA, Fertility and Reproductive Centre, Warsaw, Poland
3 Department of Nursing, Medical University, Gdansk, Poland
Study question
To assess correlation between Day 5 (D5) and Day 6 (D6) blastocyst morphology
and ploidy status.

2. Genetic Laboratory
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Summary answer
Slower developing blastocysts cryopreserved on Day 6 but at the same stage of development as those developing to the blastocyst
stage on Day 5 do not have similar chromosomal status and therefore provide a lower chance of achieving pregnancy.
What is known already
Embryos with the highest morphological scores showed a higher euploidy rate when compared with lower quality embryos. During
IVF cycles, the embryonic cohort is asynchronous in development and trophectoderm biopsy can equally be performed on D5 or D6
post-fertilization and on blastocysts of different morphological quality. It is still unknown whether blastocyst morphology and
developmental rate relate to the embryo chromosomal constitution.

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Study design, size, duration
Retrospective study including the data analysis of 61 blastocysts stage PGS cycles (median age 38 years, range 34-40) performed between August
2013 and November 2014 at INVICTA Fertility Centre, Poland.
A total of 168 blastocysts were evaluated with the NGS protocol.
Participants/materials, setting, methods
All embryos were cultured to blastocyst stage. Trophectoderm biopsy was performed on D5 (n=104) of development or, for slower growing
embryos, on D6 (n=64). The method involved whole genome amplification before NGS protocol. Ion Torrent Suite Software and Invicta
Bioinformatics Team Script were used for chromosome copy number variation analysis.

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Main results and the role of chance
50 single frozen embryo transfers of euploid blastocysts (D5-39, D6-11) were performed.

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INVICTA Genetic Laboratory
ul. Trzy Lipy 3, 80-172 Gdansk, Poland,
T: +48 58 58 58 804, E: pgd@invicta.pl;
W: www.invictagenetics.com
About INVICTA Genetic Laboratory
INVICTA is an experienced genetics laboratory (since 2000)
offering wide range Preimplantation Genetic Diagnosis testing
using state of art Next Generation Sequencing (NGS) techniques.
Wider implications of the findings
This study provides insight into determining ploidy status depending on the day of blastocyst biopsy. Slower developing blastocysts
cryopreserved on Day 6 but at the same stage of development as those developing to the blastocyst stage on Day 5 do not have similar
chromosomal status. Euploid embryos tend to show faster progression to the most advanced expansion stages when compared with
aneuploid embryos.