When Does Life Begin?:

For anyone truly interested in finding the answer to "when does life begin?" we have compiled sufficient information to support a conclusion. The following references illustrate the fact that a new human embryo, the starting point for a human life, comes into existence with the formation of the one-celled zygote:

When Does Life Begin?

"Development of the embryo begins at Stage 1 when a sperm fertilizes an oocyte and together they form a zygote."

  — England, Marjorie A. Life Before Birth. 2nd ed. England: Mosby-Wolfe, 1996, p.31

"Human development begins after the union of male and female gametes or germ cells during a process known as fertilization (conception).

"Fertilization is a sequence of events that begins with the contact of a sperm (spermatozoon) with a secondary oocyte (ovum) and ends with the fusion of their pronuclei (the haploid nuclei of the sperm and ovum) and the mingling of their chromosomes to form a new cell. This fertilized ovum, known as a zygote, is a large diploid cell that is the beginning, or primordium, of a human being."

  — Moore, Keith L. Essentials of Human Embryology. Toronto: B.C. Decker Inc, 1988, p.2

---

There is NO debate within the medical community as to when life begins. In the opinions of the scientic and medical communities, life begins at conception, as is clearly stated in the following texts:

• The Developing Human: Clinically Oriented Embryology, 6th ed.
  Keith L. Moore, Ph.D. & T.V.N. Persaud, Md., (Philadelphia: W.B. Saunders Company, 1998), 2-18.
  
  "The Zygote results from the union of an oocyte and a sperm. A zygote is the beginning of a new human being. Human development begins at fertilization, the process during which a male gamete or sperm ... unites with a female gamete or oocyte ... to form a single cell called a zygote. This highly specialized, totipotent cell marks the beginning of each of us as a unique individual."
  
  
• Essentials of Human Embryology
  William J. Larsen, (New York: Churchill Livingstone, 1998), 1-17.
  
  "In this text, we begin our description of the developing human with the formation and differentiation of the male and female sex cells or gametes, which will unite at fertilization to initiate the embryonic development of a new individual. ... Fertilization takes place in the oviduct... resulting in the formation of a zygote containing a single diploid nucleus. Embryonic development is considered to begin at this point... This moment of zygote formation may be taken as the beginning or zero time point of embryonic development."
  
  
• Human Embryology & Teratology
  Ronan R. O'Rahilly, Fabiola Muller, (New York: Wiley-Liss, 1996), 5-55.
  
  "Fertilization is an important landmark because, under ordinary circumstances, a new, genetically distinct human organism is thereby formed... Fertilization is the procession of events that begins when a spermatozoon makes contact with a secondary oocyte or its investments...  The zygote... is a unicellular embryo... "The ill-defined and inaccurate term pre-embryo, which includes the embryonic disc, is said either to end with the appearance of the primitive streak or ... to include neurulation. The term is not used in this book."
  
  
• Cloning Human Beings
  Report and Recommendations of the National Bioethics Advisory Commission. Rockville, MD: GPO, 1997, Appendix-2.
  
  "Embryo: the developing organism from the time of fertilization until significant differentiation has occurred, when the organism becomes known as a fetus."
  
  
• The Harper Collins Illustrated Medical Dictionary
  Dox, Ida G. et al. New York: Harper Perennial, 1993, p. 146]
  
  "Embryo: An organism in the earliest stage of development; in a man, from the time of conception to the end of the second month in the uterus."
  
  
• Test-Tube Babies
  Walters, William and Singer, Peter (eds.). Melbourne: Oxford University Press, 1982, p. 160
  
  "Embryo: The early developing fertilized egg that is growing into another individual of the species. In man the term 'embryo' is usually restricted to the period of development from fertilization until the end of the eighth week of pregnancy."
  
  
• Medical Embryology
  Langman, Jan. 3rd edition. Baltimore: Williams and Wilkins, 1975, p. 3
  
  "The development of a human being begins with fertilization, a process by which two highly specialized cells, the spermatozoon from the male and the oocyte from the female, unite to give rise to a new organism, the zygote."
  
  
• Van Nostrand's Scientific Encyclopedia
  Considine, Douglas (ed.). 5th edition. New York: Van Nostrand Reinhold Company, 1976, p. 943
  
  "Embryo: The developing individual between the union of the germ cells and the completion of the organs which characterize its body when it becomes a separate organism.... At the moment the sperm cell of the human male meets the ovum of the female and the union results in a fertilized ovum (zygote), a new life has begun.... The term embryo covers the several stages of early development from conception to the ninth or tenth week of life."
  
  
• Dr. John Eppig, Senior Staff Scientist, Jackson Laboratory (Bar Harbor, Maine) and Member of the NIH Human Embryo Research Panel
  Panel Transcript, February 2, 1994, p. 31
  
  "I would say that among most scientists, the word 'embryo' includes the time from after fertilization..."
  
  
• Langman's Medical Embryology
  Sadler, T.W. 7th edition. Baltimore: Williams & Wilkins 1995, p. 3
  
  "The development of a human begins with fertilization, a process by which the spermatozoon from the male and the oocyte from the female unite to give rise to a new organism, the zygote."
  
  
• Jonathan Van Blerkom of University of Colorado, expert witness on human embryology before the NIH Human Embryo Research Panel
  Panel Transcript, February 2, 1994, p. 63
  
  "The question came up of what is an embryo, when does an embryo exist, when does it occur. I think, as you know, that in development, life is a continuum.... But I think one of the useful definitions that has come out, especially from Germany, has been the stage at which these two nuclei [from sperm and egg] come together and the membranes between the two break down."
  
  
• Before We Are Born: Essentials of Embryology and Birth Defects
  Moore, Keith L. and Persaud, T.V.N. 4th edition. Philadelphia: W.B. Saunders Company, 1993, p. 1
  
  "Zygote. This cell, formed by the union of an ovum and a sperm (Gr. zyg tos, yoked together), represents the beginning of a human being. The common expression 'fertilized ovum' refers to the zygote."
  
  
• Human Embryology
  Larsen, William J. 2nd edition. New York: Churchill Livingstone, 1997, p. 17
  
  "The chromosomes of the oocyte and sperm are...respectively enclosed within female and male pronuclei. These pronuclei fuse with each other to produce the single, diploid, 2N nucleus of the fertilized zygote. This moment of zygote formation may be taken as the beginning or zero time point of embryonic development."
  
  
• Patten's Foundations of Embryology
  Carlson, Bruce M. 6th edition. New York: McGraw-Hill, 1996, p. 3
  
  "Almost all higher animals start their lives from a single cell, the fertilized ovum (zygote)... The time of fertilization represents the starting point in the life history, or ontogeny, of the individual."
  
  
• Remaking Eden: Cloning and Beyond in a Brave New World
  Silver, Lee M. New York: Avon Books, 1997, p. 39
  
  "Animal biologists use the term embryo to describe the single cell stage, the two-cell stage, and all subsequent stages up until a time when recognizable humanlike limbs and facial features begin to appear between six to eight weeks after fertilization....
  
  "A number of specialists working in the field of human reproduction have suggested that we stop using the word embryo to describe the developing entity that exists for the first two weeks after fertilization. In its place, they proposed the term pre-embryo....
  
  "I'll let you in on a secret. The term pre-embryo has been embraced wholeheartedly by IVF practitioners for reasons that are political, not scientific. The new term is used to provide the illusion that there is something profoundly different between what we nonmedical biologists still call a six-day-old embryo and what we and everyone else call a sixteen-day-old embryo.
  
  "The term pre-embryo is useful in the political arena -- where decisions are made about whether to allow early embryo (now called pre-embryo) experimentation -- as well as in the confines of a doctor's office, where it can be used to allay moral concerns that might be expressed by IVF patients. 'Don't worry,' a doctor might say, 'it's only pre-embryos that we're manipulating or freezing. They won't turn into real human embryos until after we've put them back into your body.'"
  
  
• Human Embryology, 3rd ed.
  Bradley M. Patten, (New York: McGraw Hill, 1968), 43.
  
  "It is the penetration of the ovum by a spermatozoan and resultant mingling of the nuclear material each brings to the union that constitutes the culmination of the process of fertilization and marks the initiation of the life of a new individual."
  
  
• Biological Principles and Modern Practice of Obstetrics
  J.P. Greenhill and E.A. Friedman, (Philadelphia: W.B. Sanders, 1974), 17.
  
  "The zygote thus formed represents the beginning of a new life."
  
  
• Pathology of the Fetus and the Infant, 3d ed.
  E.L. Potter and J.M. Craig, (Chicago: Year Book Medical Publishers, 1975), vii.
  
  "Every time a sperm cell and ovum unite a new being is created which is alive and will continue to live unless its death is brought about by some specific condition."

---

In 1981, a United States Senate judiciary subcommittee received the following testimony from a collection of medical experts (Subcommittee on Separation of Powers to Senate Judiciary Committee S-158, Report, 97th Congress, 1st Session, 1981):

• Professor Micheline Matthews-Roth
  Harvard University Medical School
  
  "It is incorrect to say that biological data cannot be decisive...It is scientifically correct to say that an individual human life begins at conception."
  
  
• Dr. Alfred M. Bongioanni
  Professor of Pediatrics and Obstetrics, University of Pennsylvania
  
  "I have learned from my earliest medical education that human life begins at the time of conception."
  
  
• Dr. Jerome LeJeune
  Professor of Genetics, University of Descartes
  
  "After fertilization has taken place a new human being has come into being. [It] is no longer a matter of taste or opinion...it is plain experimental evidence. Each individual has a very neat beginning, at conception."
  
  
• Professor Hymie Gordon
  Mayo Clinic
  
  "By all the criteria of modern molecular biology, life is present from the moment of conception."
  
  
• Dr. Watson A. Bowes
  University of Colorado Medical School
  
  "The beginning of a single human life is from a biological point of view a simple and straightforward matter — the beginning is conception."
  

The official Senate report reached this conclusion:

Physicians, biologists, and other scientists agree that conception marks the beginning of the life of a human being - a being that is alive and is a member of the human species. There is overwhelming agreement on this point in countless medical, biological, and scientific writings.

For more information on some of the topics discussed on this page, we recommend:

THE CODE FOR HUMAN LIFE by Frederick T. Zugibe, M.S., M.D., Ph.D., FCAP, FACC, FAAFS

The Definition of Life: Can the fertilized egg be included? A compilation of evidence by Christina Rutten