Why is it common to transfer embryos on day 5?

This is an automatically translated article.

This article is professionally consulted by Master, Doctor Nguyen Thi Cam Van - IVF Lab Doctor - Reproductive Support Center - Vinmec Times City International Hospital.
Currently, day 5 embryo transfer is a trend of many major IVF centers around the world. Blastocyst stage embryo transfer offers a higher success rate than day 3 embryo transfer because the implantation potential of day 5 embryos is much higher than that of day 3.

1. Stages of embryo formation

Prokaryotic stage (Day 0 - Day 1)
Sperm and egg fuse: At this stage, the nuclei from each gamete are next to each other forming a pronuclei that can be observed after 16- 18 hours insemination. This is how embryologists determine whether fertilization has occurred. Soon, the two pronuclei combine and form the embryo's DNA.
Divisional phase (Day 1 - Day 3)
Over the next few hours, the embryo will begin to divide from the first cell into 2 cells and after about 24 hours into 4 cells, 8 cells and so on. ..
Early morula stage (Day 3 - Day 5)
At about 3 to 4 days after fertilization, the meiotic cells of the embryo are spherical and the embryo is called the morula.
The blastocyst stage (Day 5+)
The cells begin to transform into the inner cell mass (ICM) and the trophectoderm (TE). These are parts of the embryo that will later become a fetus from the endoplasmic reticulum and the placenta from the ectoderm.

2. Why is it common to transfer embryos on day 5?

High success rate of embryo transfer
Day 5 embryos have much higher implantation potential than day 3 embryos, thereby increasing the chances of pregnancy for infertile couples.
Reducing the risk of multiple pregnancies
When transferring blastocysts with high implantation potential, the number of embryos to be transferred will be reduced. In the majority of cases, the mother only needs to transfer one embryo on day 5 to ensure a higher chance of conception than day 3 embryo transfer. Thereby reducing the risk of multiple pregnancy, reducing pregnancy complications caused by fetal skin. .

Safer genetic testing
To screen for genetic diseases before embryo transfer in couples with a high chance of passing this genetic disease on to their children, embryologists wait until the embryo's day 5 then genetic testing will begin. Because the extraction of genetic material from embryonic cells at day 3 will be more dangerous and affect the quality of the embryo than from the 5-day blastocyst stage. Currently, the leading IVF centers in the world perform preimplantation genetic screening tests on day 5 embryos. The reason is because: performing a day 5 embryo biopsy will provide a large amount of genetic material. transmission is larger than embryos on day 3. From there, genetic diagnosis results will be more accurate. At the same time, blastocyst biopsies that remove 3-4 cells from hundreds of cells will have less effect on embryo development than day 3 embryos, which only have 8 cells. The process of freezing embryos after biopsy and thawing before transfer did not affect the quality of embryos, with the survival rate after thawing reaching nearly 100%.

Safer to freeze embryos and thaw embryos
Assisted Reproductive Center - Vinmec International General Hospital is the leading center in the implementation of general assisted reproductive techniques and artificial insemination in particular.
Infertility examination and treatment at Vinmec
Here, customers will receive accurate examination and advice on embryo freezing services with a team of leading experts in the field of Obstetrics and Gynecology in the country and internationally. Vinmec doctors are all trained in countries with leading medical backgrounds in the world (USA, Singapore, Japan, Australia...)

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Reference source: Fertilityiq.com