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Objective
To assess correlation between blastocyst morphology and chromosomal status.
Design
Observational research study.
Setting
An IVF clinic and a specialist preimplanation genetic diagnosis (PGD) laboratory.
Patient(s)
Ninety-three couples undergoing IVF treatment in combination with chromosome screening of embryos.
Intervention(s)
Five hundred blastocysts underwent trophectoderm biopsy and comprehensive chromosome screening using comparative genomic hybridization (CGH). The morphology of the embryos was evaluated using standard methods.
Main outcome measure(s)
Association of aneuploidy and morphologic score.
Result(s)
A total of 56.7% of blastocysts were aneuploid. One-half of the grade 5/6 blastocysts were euploid, compared with only 37.5% of embryos graded 1/2, suggesting an effect of aneuploidy on blastocyst development. Aneuploidy also had a negative effect on inner cell mass and trophectoderm grades. Morphologically poor blastocysts had a higher incidence of monosomy and abnormalities affecting several chromosomes. The gender ratio was significantly skewed in relation to morphology. A total of 72% of blastocysts attaining the highest morphologic scores (5AA and 6AA) were found to be male, compared with only 40% of grade 3 embryos.
Conclusion(s)
Morphology and aneuploidy are linked at the blastocyst stage. However, the association is weak, and consequently, morphologic analysis cannot be relied on to ensure transfer of chromosomally normal embryos. A significant proportion of aneuploid embryos are capable of achieving the highest morphologic scores, and some euploid embryos are of poor morphology. Gender was associated with blastocyst grading, male embryos developing at a significantly faster rate than females.
Key Words
Morphology
chromosome
aneuploidy
blastocyst
preimplantation genetic screening
single embryo transfer
implantation
in vitro fertilization
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Copyright © 2011 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.
A common question we get asked about the process is, “How many normal (euploid) embryos will I produce?” Demko et al addressed this very issue in a recent publication. They analyzed the relationship between maternal age and the rate of embryos that tested as euploid, the average number and proportion of normal embryos per IVF cycle and the possibility of retrieving at least one normal embryo.
Results of Study on Age and Number of Eggs Obtained After Preimplantation Genetic Screening
The study analyzed more than 46,000 embryos between 2009 and 2014.
- In women aged 27 to 35 years, the median proportion of euploid embryos in each cycle remained constant at approximately 35% in day-3 biopsies and approximately 55% in day-5 biopsies, but it decreased rapidly after age 35.
- On average, women in their late 20s had four euploid embryos (day 3 or day 5) per cycle, but this number decreased linearly (R2 R 0.983) after 35 years of age.
- The effect of maternal age on the possibility of retrieving at least one normal embryo was similar, with a rapid exponential decline (R2 1⁄4 0.986).
- At age 35, at least one euploid embryo can be expected in 85% of all cycles; this percentage drops to approximately 75% at age 40, and to approximately 45% by age 44.
- Across all maternal ages, the euploid proportion and number of embryos per cycle were counterbalanced, so the number of euploid embryos per cycle was the same for day-3 and day-5 biopsies. This suggests that the loss of embryos from day 3 to day 5 was primarily due to aneuploidy.
They concluded that (1) 33% to 50% of all embryos screened in women aged 18 to 48 years are aneuploid and (2) the number and percentage of euploid embryos decreases with advancing maternal age.
At InVia Fertility Specialists, we have been offering SMART IVF (PGD or PGS) for many years. Currently, using this technology, we are having pregnancy rates approximating 70% with the transfer of a single embryo.
To see a fertility specialist with a high success rate using single embryo transfer, make an appointment at one of InVia's four Chicago area fertility clinics.