PGS principle

PGS theory is based on 3 important facts:

  1. Human embryos are often aneuploid:
    • at the age 30-35  30-40% of blastocysts are aneuploid
    • at the age of 40-42 70-80% blastocysts are aneuploid [ Fragouli et al., 2012]
  2. Aneuploidy is almost always lethal – leads to developmental arrest of the embryo due to shortage or excess of genetic material [Scott at al., 2012]
  3. Influence of chromosome abnormalities on embryonic morphology is very insignificant. In other words a “good looking embryo” can be aneuploid. [Alfarawati et al., 2011]

Consequences

Aneuploid embryos can be chosen for embryo transfer, because they looked as good or even better than their euploid siblings which sadly were not chosen for transfer. Very often transfer of aneuploid embryo in the uterus will result in no pregnancy at all or rather often in early pregnancy loss before 12 weeks. Only selected types of chromosome mistakes are compatible with development throughout the whole pregnancy and may result, for example, in live birth of a Down syndrome baby (trisomy 21) or Turner syndrome (45, XO). 

Conclusion: A wrong chromosome number in an embryo is the major reason for a morphologically good embryo not being able to attach and/or progress to a live born baby.

Solution

Testing of all 23 chromosome pairs in “good looking“ blastocysts to choose those for transfer which do not only have the highest chance to attach, but also to stay and result in live birth.

This embryo testing is called Pre-implantation genetic screening = PGS.

Major principle of PGS for 23 chromosome pairs is to sort out such good in morphology embryos with a wrong chromosome number and to use them neither  for fresh transfer nor for freezing.

PGS does not make your embryos better. It helps to choose the most viable embryos from those you have. PGS does not increase the cumulative result of one IVF stimulation including all the transfers fresh and frozen from one or more IVF cycles. But it increases the implantation rates, clinical pregnancy rates and live birth rates per embryo transfer. Hence PGS for 23 chromosome pairs reduces time you spend to achieve pregnancy and live birth.

The higher the age of the egg used to create pregnancy, the higher risk of it being abnormal, the higher risk to pick up an abnormal embryo for transfer based only on embryo morphology.

The higher the age of the women the higher her benefit  from choosing an embryo for transfer based on both morphological evaluation and PGD for 23 chromosome pairs.

Conclusion: PGS for 23 chromosome pairs eliminates the negative effect of maternal age on implantation (if there are chromosomally normal embryos found and embryo transfer is possible)

“…I am a single woman and when one is lonely, one is very sensitive…You saw me as a person and I felt that you can help me…”

Birgita

 

“…Well the Millennium shift came, the year 2000, we all remember what we did then, right? I got cancer, Hodgkin's lymphoma... And when I stand here now 17 years later, you understand that it went well! Except for one important thing…"

Hillevi

“…When I left the clinic and walked down the Nevsky Prospect I knew I was pregnant — and the feeling was right! 9 month after her visit at the AVA Clinic Alexander was born!”

Ewa and Sten


Having questions? Ask our doctors now!

A blog by Tone Bråten

A blog — to help you on your journey to become parents!

Our patients tell their stories



  • Willeke and Mario from Netherlands come to AVA-Peter for egg donation treatment… Enjoy this touching and sincere documentary by Jorien van Nes
       
    Mum through embryo donation
    Marie Granmar is my very dear patient from more than 8 years ago. Please listen to Marie’s interview on TV4 7 March 2019 in Sweden
    More
    "I became pregnant with an embryo adoption”
    One more story about our dear patient Cilla Holm by Tara Magazine, Sweden
    More
    Titiyo became this year's Comeback Mum: "I've broken the norm"
    More
    Monika and André pay 240,000 SEK for having a child
    More
    "Had to travel abroad to get pregnant after 8 IVF attempts in Norway"
    Interview with our patient Elin Renate by TV2 Norway
    More
    Report on us on Norwegian Television TV 2
    More
    Enjoy our dear patient Cilla's story, who has been interviewed by the "Dagens Nyheter", daily newspaper in Sweden
    More
    Report on us and our dear patient Hillevi on SVTPlay & SVTNews
    More
    FacebookInstagram