Natural selection from egg to live birth

Humans produce a good amount of abnormal eggs, which contain one or several chromosomes more or less than normal. Having even one chromosome less or more will have a huge negative impact on the egg’s and later embryo’s chance to develop to live birth. The incidence of such eggs grows with the age of a woman.

The process of natural selection eliminates such abnormal embryos — they just stop at some point due to their internal reasons. There will be always more eggs than embryos on day 3, and more embryos on day 3 than on day 5. At the same time the percentage of abnormal embryos will decrease from day 1 to day 5.  Still 1 in 4 morphologically good embryos is abnormal even on day 5 in the age around 30 and 3 in 4 morphologically good blastocysts are abnormal in the age around 40. 

A chromosomally abnormal embryo may look under the microscope very good even at the age of 5 days after long natural selection, even better than all other embryos in the cohort and be selected for the embryo transfer.

The earlier embryonic stage the more intensive the natural selection process is. Still as you see at least 1 in 4 blastocysts is still abnormal and can be chosen for embryo transfer. Hence the natural selection process will continue in-utero and may result in early miscarriage or no implantation at all, if the embryo had one or several chromosomes less or more than needed.

The majority of embryos with incorrect chromosome number will stop in development  even before pregnancy can be diagnosed by blood test. Some abnormal embryos, if having been transferred in the uterus, will result in positive pregnancy test (biochemical pregnancy test) but will not be found by an ultrasound examination (will not turn into a clinical pregnancy. Only very low percentage of abnormal embryos can make it to clinical pregnancy and almost all of them will be miscarried before 12 weeks. The nature has a very powerful and strong control over humans as species and does not allow the species to deviate from the 46 chromosome pattern. Only selected types of chromosome mistakes are compatible with development throughout the whole pregnancy and may result in life birth of a baby with certain health problems (for example Down syndrome (trisomy 21) or Turner syndrome (45, XO).

Conclusion: Abnormal chromosome number impairs embryonic developmental processes and is the major reason for implantation failure or early pregnancy loss

Get free consultation!

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

    Podcast about embryonic and maternal reasons of pregnancy losses and how we solve this
    Listen to the Podcast!
    The Egg Solution
    Aftenposten, 27 September 2019, Norway. Miriam Lund Knapstad, Helle Aarnes
    Olga is the miracle doctor who gives baby guarantee, Sweden. 6 August 2019. Text & Malin Aunsbjerg
    Cilla Holm became a mother on her own – this is her new Liv (life)
    Dagens Nyheter, Sweden. 7 May 2019
    Russian baby guarantee is the Swedes’ last chance
    Svenska Dagbladet, Sweden. 7 April 2019
    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
    "I became pregnant with an embryo adoption”
    One more story about our dear patient Cilla Holm by Tara Magazine, Sweden
    Titiyo became this year's Comeback Mum: "I've broken the norm"
    Monika and André pay 240,000 SEK for having a child
    "Had to travel abroad to get pregnant after 8 IVF attempts in Norway"
    Interview with our patient Elin Renate by TV2 Norway
    Report on us on Norwegian Television TV 2
    Enjoy our dear patient Cilla's story, who has been interviewed by the "Dagens Nyheter", daily newspaper in Sweden
    Report on us and our dear patient Hillevi on SVTPlay & SVTNews