in china i think they do actually

Because we count BIRTHdays, not CONCEVIEDdays. Sometimes it's hard to pinpoint the day of conception, but the day you are born is a totally different story.

- there is a controversy about the beginning of pregnancy. - the gestational age cannot always be evaluated with accuracy. 1) "Controversy over the 'beginning of pregnancy' usually occurs in the context of the abortion debate. Depending on where pregnancy is considered to begin, some methods of birth control or infertility treatment might be considered abortifacient. The controversy is not a scientific issue since knowledge of human reproduction and development has become very refined. Rather, the issue has social, political and legal ramifications since some equate the 'beginning of pregnancy' with the 'beginning of [individual's] life'.[citation needed] The latter question may have no clear definition since, biologically, life is usually regarded as a continuum." 2) "Previously, pregnancy was defined in terms of conception. However, in the absence of an accurate understanding of human development, early notions about the timing and process of conception were often vague. For example, Webster's Dictionary defines "pregnant" (or "pregnancy") as "having conceived" (or "the state of a female who has conceived"), in its 1828 and 1913 editions. Both the 1828 and 1913 editions of Webster's Dictionary said that to "conceive" meant "to begin the formation of the embryo." It was only in 1875 that Oskar Hertwig discovered that fertilization includes the penetration of a spermatozoon into an ovum. Thus, the term "conception" was in use long before the details of fertilization were discovered. By 1966, a more precise meaning of the word "conception" could be found in common-use dictionaries: the formation of a viable zygote. In 1959, Dr. Bent Boving suggested that the word "conception" should be associated with the process of implantation instead of fertilization. Some thought was given to possible societal consequences, as evidenced by Boving's statement that "the social advantage of being considered to prevent conception rather than to destroy an established pregnancy could depend on something so simple as a prudent habit of speech." In 1965, the American College of Obstetricians and Gynecologists (ACOG) adopted Boving’s definition: "conception is the implantation of a fertilized ovum." The 1965 ACOG definition was imprecise because, by the time it implants, the zygote is called a blastocyst, so it was clarified in 1972 to "Conception is the implantation of the blastocyst." Some dictionaries continue to use the definition of conception as the formation of a viable zygote." Source and further information: http://en.wikipedia.org/wiki/Beginning_of_pregnancy_controversy 3) "Gestational age is usually considered to be the age of an embryo or fetus (or newborn infant) from the first day of the woman's last menstrual period (LMP). This standard system of counting the progression of pregnancy starts approximately two weeks before fertilization takes place; it does not in itself constitute the beginning of pregnancy. There is some controversy over the beginning of pregnancy, and alternative counting systems have been suggested. A full-term human pregnancy is considered to be 40 weeks (280 days), though pregnancy lengths between 38 and 42 weeks are considered normal. A fetus born prior to the 37th week of gestation is considered premature and faces increased risk of morbidity and mortality. An approximation of the due date is given by Naegele's rule. The gestational age should not be confused with the fertilization age, (also called conceptional age or developmental age) of an embryo or fetus; the fertilization age is always counted from fertilization, and the gestational age is usually greater by about two weeks. The events of prenatal development usually occur at known gestational ages. The gestational timing of a toxin exposure or infection can be used to predict the potential consequences to the fetus. Calculations of gestational age from LMP are sometimes incorrect due to normal variation from the average ovulation date. The gestational age of an individual infant can be more accurately estimated from: 1. The mother's knowledge of the date of sexual intercourse. 2. The mother's knowledge of fertility signs related to ovulation. The needed observations are normally made by mothers who use fertility awareness methods to get pregnant. 3. Examination of the newborn infant. In the twentieth century, doctors (especially pediatricians) were trained to recognize the physical changes occurring to the fetus in the latter half of pregnancy so that a maturational age could be estimated. 4. An obstetric ultrasound ("dating scan", in the UK routinely offered around 12 weeks) during the pregnancy, whereby sizes of certain fetal body parts are measured. The fertilization age of children conceived by in vitro fertilization is known to the hour." Source and further information: http://en.wikipedia.org/wiki/Gestational_age 4) However, those notions are used for fetuses and newborns, and they are particularly relevant for early or late term newborns. Further information: http://aappolicy.aappublications.org/cgi/content/full/pediatrics;114/5/1362 http://www.drhull.com/EncyMaster/G/gestational_age.html

In some countries, they do.

get outta here! that would make me even older!