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Controversy over the beginning of pregnancy occurs in different contexts, particularly being discussed within the abortion debate in the United States according to groups such as the Guttmacher Institute. Depending on when pregnancy is considered to begin, some methods of birth control as well as some methods of infertility treatment might be considered to work as an abortifacient. The controversy is not primarily a scientific issue since knowledge of human reproduction and development has become very refined; linguistic questions remain debated for other reasons. The issue poses larger social, legal, medical, and political ramifications should one equate the 'beginning of pregnancy' with the 'beginning of an individual human being's life', a position that has been taken by groups such as Concerned Women for America.〔("The Implications of Defining When a Woman Is Pregnant" ). ''The Guttmacher Report on Public Policy''. May 2005, Volume 8, Number 2.〕 A major complication is that ideological and religious concepts such as "ensoulment" (whether or not a human being is said to have gone from mere matter to having a spiritual entity inside) and "personhood" (whether or not a human being is said to be a distinct individual with innate human rights versus otherwise) exist outside of scientific analysis, and thus many individuals have argued that the beginning of pregnancy cannot be determined strictly through physical evidence alone. No experiment exists (or can exist) to measure the spirituality of an object or living thing the way that height, temperature, weight, etc can be studied. Generally speaking, ideological and religious commentaries have argued that pregnancy should be stated as beginning at the first, exact moment of conception in which a human sperm makes full contact with an egg cell (this is easily visualized by picturing the outside of the egg as a single sperm hits it), many of these arguments being related to the anti-abortion movement. That doctrine has not found acceptance scientifically. In contrast, scientific and/or otherwise non-ideological commentaries have argued that the duration of pregnancy begins at some other point such as when the fertilization process ends (when a new, independent cell genetically distinct from the prior egg and sperm exists) and when implantation occurs (when the new set of cells lodges itself against the uterine wall, allowing it to grow rapidly). The ambiguity's implications mean that, outside of the scientific community, the definitions of what is "abortion" and what is "contraception" are not agreed upon.〔 ==Definitions of pregnancy beginning== Traditionally, doctors have measured pregnancy from a number of convenient points, including the day of last menstruation, ovulation, fertilization, implantation and chemical detection. This has led to some confusion about the precise length of human pregnancy, as each measuring point yields a different figure. At its 2004 Annual Meeting, The American Medical Association passed a resolution in favor of making "Plan B" emergency contraception available over-the-counter, and one of the claims in the resolution was that hormonal contraception that may affect implantation "cannot terminate an established pregnancy."〔(FDA Rejection of Over-The-Counter Status for Emergency Contraception Pills ) ''American Medical Association House of Delegates'' Resolution:443. Retrieved April 30, 2007〕 Similarly, the British Medical Association has defined an "established pregnancy" as beginning at implantation.〔 "The term 'abortion' is used throughout this paper to refer to the induced termination of an established pregnancy (i.e. after implantation)."〕 The legal definition in the United Kingdom is not clear.〔 – "It is generally assumed that when the Act states that ‘pregnancy has not exceeded its 24th week’ it means 24 weeks since the first day of the woman's last period. But this is not clear – particularly if there is evidence that conception had taken place on a day after this....The Attorney General said, in 1983 (see Brazier 1992 page 293-4) that there is no pregnancy until implantation. This is persuasive but not binding precedence." 〕 Other definitions exist. The American Heritage Stedman's Medical Dictionary defines "pregnancy" as "from conception until birth."〔The American Heritage Stedman's Medical Dictionary, 2002〕 Definitions like this may add to a lay person's confusion, as "conception" in a scientific context may be defined as fertilization, in a medical context can mean either fertilization or implantation〔http://www.acog.org/~/media/Committee%20Opinions/Committee%20on%20Ethics/co360.pdf〕 but in lay terms may mean both.〔http://www.merriam-webster.com/dictionary/conception〕 Whether conception refers to fertilization or implantation would seemingly even impact "established pregnancies" such as an ectopic pregnancy. If conception is defined as at implantation, ectopic pregnancies could not be called pregnancies. However, some medical professionals who oppose birth control, including prominent member of Focus on the Family Walter Larimore, have argued that the medical definition of conception should include fertilization.〔Larimore, Walter L., MD, et al. ("Response: Does Pregnancy Begin at Fertilization?" ) Family Medicine, November–December 2004.〕 Finally, the standard historical method of counting the duration of pregnancy begins from the last menstruation and this remains common with doctors, hospitals, and medical companies.〔''Doctor:''(【引用サイトリンク】title=Due Date Calculator ) ''Hospital:''(【引用サイトリンク】title=What is a trimester? ) ''Medical company:''(【引用サイトリンク】title=Stages of Development: Pregnancy )〕 This system is convenient because it is easy to determine when the last menstrual period was, while both fertilization and implantation occur out of sight. An interesting consequence is that the dating of pregnancy measured this way begins two weeks before ovulation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「beginning of pregnancy controversy」の詳細全文を読む スポンサード リンク
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