[marajade]

http://www.guttmacher.org/pubs/tgr/08/2/gr080207.html

"Between one-third and one-half of all fertilized eggs never fully implant. A pregnancy is considered to be established only after implantation is complete."

[FJ290]

I don't see that the article really proved your point. Implantation can be prevented due to many factors, like drugs, spermicides, health issues, etc.