There are a number of links.
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(Excerpt) One study testing hormones for ovulation and pregnancy found that 61.9% of conceptuses were lost prior to 12 weeks, and 91.7% of these losses occurred subclinically, without the knowledge of the once pregnant woman.(End)
Abortion - Wikipedia, the free encyclopedia
(Excerpt) It is estimated that up to half of all fertilized eggs die and are lost (aborted) spontaneously, usually before the woman knows she is pregnant.(End)
http://www.nlm.nih.gov/medlineplus/ency/article/001488.htm
(Excerpt) Many women, before realizing a life has begun forming within them, may miscarry without knowing it-assuming their miscarriage is merely a heavier period. Therefore, the miscarriage rate may be closer to 40 or 50 percent.
http://www.allaboutlifechallenges.org/miscarriage-statistics.htm
(Excerpt) Early spontaneous abortion (the most prevalent) is usually due to fetal malformations or chromosomal abnormalities.......
It is estimated that at least 20% of all pregnancies end in miscarriage (estimates range from 15% to 75%). (End)
http://www.infoplease.com/ce6/sci/A0935691.html
The 20% noted is for spontaneous abortions which occurred after the women knew they were pregnant. Most spontaneous abortions occur within hours or days and are mis-diagnosed as a monthly period.
Following are a couple of points to ponder.
Blighted ovum: A fertilized ovum (egg) that did not develop or whose development ceased at an early stage, before 6 or 7 weeks of gestation. On the ultrasound examination of a blighted ovum, only the gestational sac that normally surrounds the embryo can be seen. There is usually no embryo inside the gestational sac.
http://www.medterms.com/script/main/art.asp?articlekey=30956
Chromosomal abnormalities of the fetus are the most common cause of early miscarriages, including blighted ovum (see above). Each of the causes will be described below.
Chromosomes are microscopic components of every cell in the body that carry all of the genetic material that determine hair color, eye color, and our overall appearance and makeup.
http://www.medicinenet.com/miscarriage/page2.htm
If you take note of the last one chromosomes carry the genetic material that determine our "overall appearance and makeup". Our makeup. What makes us human beings.
As these sites note the majority of spontaneous abortions are due to genetic mutations or chromosomal abnormalities. We already know some babies are born with severe abnormalities so it's reasonable to ask how severe is/was the mutations or abnormalities that resulted in those spontaneous abortions.
We are our genes. If I recall correctly we share 95% or more of our genes with chimpanzees. For the smart asses on here I'm not suggesting the genetic abnormalities in human cells means they're chimpanzee cells. The point is a large portion of fertilized cells or embryos may not be human beings due to the severe mutations. Whether it's 50% or 1% it means not
all fertilized cells or embryos are human beings and that's the point. The Fairy Duster misses a few cells here and there. Well, actually, more than a few.
That means RStringfield's determination of what constitutes a human being is just as valid as anybody else as it's obvious the Fairy Duster does not sprinkle human-ness on a cell or embryo just so it can spontaneously abort due to genetic mutation.
Furthermore, one article talks about fertilized cells and embryos saying, "A fertilized ovum (egg) that did not develop or whose development ceased at an early stage....."
Ceased at an early stage. "It" grew. The point is what was the "it"?
The only logical conclusion is the cell or embryo was so genetically deficient that is was not a human being and that brings us back to the point I was making pages ago. We can not determine at the moment of fertilization whether the cell or embryo is a human being. In many cases that can only be determined at a later time. It does not mean because a cell or embryo "grew" that is was a human being. It may, for a time, do things associated with a human being but later shows it did not have the genetic makeup to become a human being.