I'm looking for data to build a timeline of the odds for survival of a fertilized egg, i.e.,

  • What are the odds it'll last a week?
  • What are the odds it'll last a month?
  • 2 months?
  • (and so on until)
  • What are the odds of it being born?

I am interested in the odds with the usual level of care in an industrialized nation (and a mother that is not trying to abort the fetus).


1 Answer 1


here I found an answer. Not sure how accurate is is, though.

Data seems to be from the US

Here is a rewrite of parts of that article:

  • 266 days before birth, all we have is a fertilized egg. (~33% chance of living birth).
    The odds are calculated using data from in-vitro fertilization, and the next stage is 66%.
    In in-vitro, some 50% of the eggs cannot fix to the uterine wall

  • 262 days before birth, the egg has implanted (~66% chance of living birth)
    After implantation, there is still a decent chance that the embryo will be aborted (and maybe the woman will not even know that she was pregnant).
    Half of the embryos that die from here on will die because of chromosome abnormalities.

  • 241 days before birth (~88%)

  • 178 days before birth, entering the second trimester (~97%) At this stage, problems are more likely to stem from the mother, not the fetus' genome. Problems with the cervix, the uterus or the placenta are (some ?) likely causes of death.

  • 89 days before birth, entering the third trimester (~99%) At this stage, doctors will consider the fetus a patient, and treat it if needed.

  • $\begingroup$ Maybe you could summarize a little bit the content of that page, in case it went down in the future. $\endgroup$
    – nico
    Aug 4, 2012 at 19:31

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .