Despite the formal scientific rejection of the term "pre-embryo", and despite the scientific fact that "embryo splitting" -- or "twinning" -- is a cloning technique, the American Medical Association has endorsed "human pre-embryo splitting" -- i.e., human cloning -- as "ethical". Note that this form of human cloning is closely associated with In Vitro Fertilization clinics. In case they haven't heard yet that there is no such thing as a "pre-embryo":
"The term 'pre-embryo' is not used here for the following reasons: (1) it is ill-defined because it is said to end with the appearance of the primitive streak or to include neurulation; (2) it is inaccurate because purely embryonic cells can already be distinguished after a few days, as can also the embryonic (not pre-embryonic!) disc; (3) it is unjustified because the accepted meaning of the word embryo includes all of the first 8 weeks; (4) it is equivocal because it may convey the erroneous idea that a new human organism is formed at only some considerable time after fertilization; and (5) it was introduced in 1986 'largely for public policy reasons' (Biggers). ... Just as postnatal age begins at birth, prenatal age begins at fertilization." (p. 88) ... 'Undesirable terms in Human Embryology': 'Pre-embryo'; ill-defined and inaccurate; use 'embryo'." ( p. 12) Ronan O'Rahilly and Fabiola Muller, Human Embryology & Teratology (New York: Wiley-Liss, 2001)
In case they haven't heard that "embryo-splitting", or "twinning" is a human cloning technique:
"Animal clones occur naturally as a result of sexual reproduction. For example, genetically identical twins are clones who happened to have received exactly the same set of genetic instructions from two donor individuals, a mother and a father." [Strachan and Read, Human Molecular Genetics 2 (2nd ed.) (New York: John Wiley & Sons, Inc., 1999), p. 508)]
"Cloning is possible by nucleus transplantation and by embryo splitting. Nucleus transplantation does not result in a genetically completely identical individual because the mitochondrial DNA originates from the ovum donor. Embryo splitting may be regarded as the artificial production of a monozygotic multiplet.", Geraedts JP, de Wert GM, "Cloning: applications in humans 1. Technical aspects", Ned Tijdschr Tandheelkd. 2001 Apr;108(4):145-50; PMID: 11383357, http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11383357.
"Cloning can occur naturally in the asexual reproduction of plants, the formation of identical twins ... The cloning of DNA, cells, tissues, organs and whole individuals is also achievable with artificial technologies. ... The cloning of a cell or an individual may be achieved through a number of techniques, including: ... blastomere separation (sometimes called "twinning" after the naturally occurring process that creates identical twins), i.e., splitting a developing embryo soon after fertilisation of the egg by a sperm (sexual reproduction) to give rise to two or more embryos. The resulting organisms are identical twins (clones). [Australia, The Cloning of Humans (Prevention) Bill 2001 (Queensland), http://www.parliament.qld.gov.au/Parlib/Publications_pdfs/books/2001036.pdf.]
"Because early embryonic cells are totipotent, the possibility of splitting or separating the blastomeres of early preimplantation embryos to increase the number of embryos that are available for IVF treatment of infertility is being discussed Because embryo splitting could lead to two or more embryos with the same genome, the term "cloning" has been used to describe this practice. ..., AMERICAN SOCIETY OF REPRODUCTIVE MEDICINE, http://www.asrm.com/Media/Ethics/embsplit.html.
"In such cases, patients may benefit from embryo multiplication, as discussed in the study by Massey and co-workers. ... Since each early embryonic cell is totipotent (i.e., has the ability to develop and produce a normal adult), embryo multiplication is technically possible. ..., the critical period of development to ensure success in separating human blastomeres should be at the time of embryonic gene expression, which is reported in humans to be between the four- and eight-cell stages [twinning by "blastomere splitting"]. .... The second potential method of embryo multiplication is blastocyst splitting. [Professor Dr. Mithhat Erenus, "Embryo Multiplication", http://www.hekim.net/~erenus/20002001/asistedreproduction/micromanipulation/embryo_multiplication.htm]
"Ethical Considerations for Assisted Reproductive Technologies covers the American Society for Reproductive Medicine's position on several aspects of reproductive medicine, including ... micro techniques such as: zona drilling, microinjection, blastomere separation (cloning), and assisted hatching." Ethics Committee of the American Society for Reproductive Medicine, Originally published as a supplement to the ASRM medical journal (Fertility and Sterility 1994;62:Suppl 1), http://www.asrm.com/Media/Ethics/ethics94.html].
American Medical Association
Code of Medical Ethics (August 2004)
"The definitive authority on medical professionalism."
The technique of splitting in vitro fertilized pre-embryos may result in multiple genetically identical siblings. The procedure of pre-embryo splitting should be available so long as both gamete providers agree. This procedure may greatly increase the chances of conception for an infertile couple or for a couple whose future reproductive capacity will likely be diminished. Pre-embryo splitting also can reduce the number of invasive procedures necessary for egg retrieval and the necessity for hormonal stimulants to generate multiple eggs. The use and disposition of any pre-embryos that are frozen for future use should be consistent with the Council's opinion on frozen pre-embryos. (Opinion 2.141)
The use of frozen pre-embryo identical siblings many years after one child has been born raises new ethical issues. Couples might wait until they can discover the mental and physical characteristics of a child before transferring a genetically identical sibling for implantation, they might sell their frozen pre-embryos based upon the outcome of a genetically identical child, or they might decide to transplant a genetically identical sibling based on the need to harvest the child's tissue.
The Council does not find that these considerations are sufficient to prohibit pre-embryo splitting for the following reasons:
(1) It would take many years to determine the outcome of a child and most families want to complete their childbearing within a shorter time.
(2) The sale of pre-embryos can and should be prohibited.
(3) The small number of couples who might bear identical siblings solely for purposes of harvesting their tissue does not outweigh the benefits which might be derived from pre-embryo splitting. Additionally, it is not evident that a sibling would have negative psychological or emotional consequences from having acted as an organ or tissue donor. Indeed, the child may derive psychological benefits from having saved the life of a sibling.
To the extent possible, discussion of these issues should be had with gamete providers prior to pre-embryo splitting and freezing so as to inform the prospective parents of possible future ethical dilemmas. (I, III, IV, V) Issued June 1994.