Mastodawn

Science and data loaded, but:

Early human embryo mortality is a matter of considerable interest not only to reproductive biologists and fertility doctors, but also to philosophers 1, 2, theologians 3 and lawyers 4.

Most especially, becoming pregnant and having children is of overwhelming and personal importance to many women and their families. As with all biological processes, nothing works perfectly all the time 5, and failure to conceive and pregnancy loss are common problems.

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Wm.son Feb 29, 2024

However, among reputable scientific publications, including medical and reproductive biology text books, scientific reviews and primary research articles, reported mortality estimates are surprisingly varied and include: 30–70% 6, >50% 7 and 75% 8 before and during implantation; >50% 9, 73% 10 and 80% 11 before the 6 th week; 75% before the 8 th week 12; 70% in the first trimester 13; 40–50% in the first 20 weeks 14; and 46% 7, 49% 15, 50% 16– 18, >50% 19, 20, 53% 21, 54% 22, 60% 23, >60% 24, 63% 25, 26, 70% 27– 31, 50–75% 32, 76% 10, 33, 78% 34, 80–85% 35, >85% 36, and 90% 37 total loss from fertilization to term.

The variance in these estimates is striking and the scale of some implausible. 90% intrauterine mortality implies a maximal live birth fecundability of 10%, and only then if all other stages of the reproductive process are 100% efficient. .

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Wm.son Feb 29, 2024

Observed human fecundability is low compared to other animals 21, but at approximately 20–30% 9, 38 it is still higher than implied by such a high embryo mortality rate.

Such inconsistent estimates of pregnancy loss are not reassuring, nor do they provide a sound basis for either a quantitative understanding of natural human reproductive biology or an unbiased appraisal of artificial reproductive technologies.

These divergent and excessive values therefore invite scrutiny of the evidence that supports them. In this article, I identify and re-evaluate published data that contribute to claims regarding natural human embryo mortality

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Wm.son Feb 29, 2024

So, if a woman flushes this many fertilized eggs as George Carlin reminds us, is she a serial killer?

Info taken from here:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443340/

Early embryo mortality in natural human reproduction: What the data say

How many human embryos die between fertilisation and birth under natural conditions? It is widely accepted that natural human embryo mortality is high, particularly during the first weeks after fertilisation, with total prenatal losses of 70% and higher ...

PubMed Central (PMC)