Fertility 257215 226124859 2008-07-16T22:42:39Z XLinkBot 6163802 BOT--Reverting edits by [[:en:Special:Contributions/Pratte|Pratte]] to revision 224870142 (\bblogspot\.com) {{for|the quality of soil|Fertility (soil)}} {{redirect|Fertile}} '''Fertility''' is the natural capability of giving life. As a measure, "Fertility Rate" is the number of children born per couple, person or population. This is different from [[fecundity]], which is defined as the ''potential'' for reproduction (influenced by gamete production, fertilisation and carrying a pregnancy to term). In the English language, the term was originally applied only to [[female]]s, but increasingly is applied to males as well, as common understanding of [[reproduction|reproductive]] mechanisms increases and the importance of the [[male]] role is better known. [[Infertility]] is a deficient fertility. Human fertility depends on factors of [[nutrition]], [[sexual behavior]], [[culture]], [[instinct]], [[endocrinology]], timing, [[economics]], way of life, and [[emotion]]s. Animal fertility is no less complex, and may display astounding mechanisms. ==Agriculture== :''See also [[arable land]], [[fertility (soil)|soil fertility]], [[harvest]], [[Neolithic revolution]].'' Fertility is also applied to [[Farmland (farming)|farmland]]s and plants, where it implies a capacity to yield large crops of sound [[fruits]], [[seeds]] or [[vegetables]]. ==Demography== The [[fertility rate]] is a [[demography|demographic]] measure of the number of [[children]] per woman. Although it has been until recently considered to be a fairly reliable indicator of [[population]] growth, it is no longer so in much of [[Asia]]. Due to [[selective abortion]] and other factors, the ratio of women relative to men in populations is declining. Therefore, the fertility rate as it has traditionally been defined is no longer an authoritative measure of population growth in [[China]], [[India]], and [[Myanmar]]. ==Human fertility== Both women and men have [[Hormones|hormonal]] cycles which determine both when a woman can achieve [[pregnancy]] and when a man is most virile. The female cycle is approximately twenty-eight days long, but the male cycle is variable. Men can ejaculate and produce [[spermatozoon|sperm]] at any time of the month, but their [[sperm quality]] dips occasionally, which scientists guess is in relation to their internal cycle. Furthermore, age also plays a role, especially for women. ===Menstrual cycle=== {{Main|Menstrual cycle#The fertile window}} Women are fertile only about seven days in each [[menstrual cycle]]. Ovulation occurs at about the fourteenth day of their [[menstrual cycle]], this obviously being the most fertile time for females. '''The exact point of ovulation varies, however'''.<ref>[http://www.ovusoft.com/library/myths.asp Ovusoft.com] </ref> If the egg is not fertilized by the male’s sperm, the egg will break down within 1–2 days into its components (mostly protein) and be reabsorbed by the body. However, sperm can survive inside the uterus for five days. Thus, a successful conception can result during seven days of the female cycle; five days before and two days after ovulation. ===Female fertility=== The average age of menarche in the United States is about 12.5 years.<ref>http://pediatrics.aappublications.org/cgi/content/full/111/4/844?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&searchid=1&FIRSTINDEX=0&minscore=5000&resourcetype=HWCIT</ref> In postmenarchal girls, about 80% of the cycles were anovulatory in the first year after menarche, 50% in the third and 10% in the sixth year.<ref>http://www.ncbi.nlm.nih.gov/pubmed/6249519</ref> <ref>http://www3.interscience.wiley.com/journal/119590594/abstract</ref> Women's fertility peaks around the age of 19-24, and often declines after 30. With a rise in women [[Advanced maternal age|postponing pregnancy]],<ref name= "Late in Life Pregnancy Article">http://findarticles.com/p/articles/mi_m1077/is_1_62/ai_n16807720 "Late-in-life Pregnancy"</ref> this can create an [[infertility]] problem. Of women trying to get pregnant, without using fertility drugs or [[in vitro fertilization]]: *At age 30, 75% will get pregnant within one year, and 91% within four years. *At age 35, 66% will get pregnant within one year, and 84% within four years. *At age 40, 44% will get pregnant within one year, and 64% within four years.<ref>{{cite web | title=Fertility Treatment Less Successful After 35 | work=WebMD | url=http://www.webmd.com/content/article/89/100183.htm | accessmonthday=July 4 | accessyear=2006}}</ref> The above figures are for pregnancies ending in a live birth and take into account the increasing rates of miscarriage in the ageing population. According to the [[March of Dimes]], "about 9 percent of recognised pregnancies for women aged 20 to 24 ended in miscarriage. The risk rose to about 20 percent at age 35 to 39, and more than 50 percent by age 42".<ref>{{cite web | title=Pregnancy After 35 | work=March of Dimes | url=http://www.marchofdimes.com/professionals/14332_1155.asp | accessmonthday=May 21 | accessyear=2008}}</ref> Birth defects, especially those involving [[chromosome]] number and arrangement, also increase with the age of the mother. According to the March of Dimes, "At age 25, a woman has about a 1-in-1,250 chance of having a baby with [[Down syndrome]]; at age 30, a 1-in-1,000 chance; at age 35, a 1-in-400 chance; at age 40, a 1-in-100 chance; and at 45, a 1-in-30 chance."<ref>{{cite web | title=The sterility tax can be reestablished in Russia | url=http://russia-ic.com/business_law/in_depth/253/ | accessmonthday=September 22 | accessyear=2006}}</ref> The use of [[fertility medication|fertility drugs]] and/or in vitro fertilization can increase the chances of becoming pregnant at a later age. Successful pregnancies facilitated by fertility treatment have been documented in [[Pregnancy over age 50#Cases of pregnancy over 50|women as old as 67]].<ref>{{cite web|title=Spanish woman ' is oldest mother'|date=|30 December, 2006|accessdate=2006-12-30|url=http://news.bbc.co.uk/2/hi/health/6220523.stm|publisher=BBC News}}</ref> Doctors recommend that women over 30 who have been unsuccessful in trying to conceive for more than 6 months undergo some kind of fertility testing.<ref>[http://fertilitytesting.co.uk/female_fertility_tests.html Fertility Testing] (Female Fertility Testing)</ref> ===Male fertility and age=== [[Erectile dysfunction]] increases with age,<ref name=semin> [http://www.infertile.com/inthenew/sci/maleage.htm Effect of Age on Male Fertility] Seminars in Reproductive Endocrinology. Volume, Number 3, August 1991. Sherman J. Silber, M.D.</ref> but fertility does not decline in men as sharply as it does in women. There have been examples of males being fertile at 94 years old.<ref name=semin/> ====Cause of decline==== [[Sperm count]] declines with age, with men aged 50-80 years producing sperm at an average rate of 75% compared with men aged 20-50 years. However, an even larger difference is seen in how many of the [[seminiferous tubules]] in the [[testes]] contain mature sperm; *In males 20-39 years old, 90% of the seminiferous tubules contain mature sperm. *In males 40-69 years old, 50% of the seminiferous tubules contain mature sperm. *In males 80 years old and older, 10% of the seminiferous tubules contain mature sperm.<ref name=semin/> This does not directly correlate with any absolute decline in fertility, since there are still many sperm cells left for fertilization.<ref name=semin/> ==Infertility== :''see also [[Infertility]] ==See also== * [[Birth control]] * [[Demographic-economic paradoxon]] * [[Family planning]] * [[Fertility and diet]] * [[Fertility clinic]] * [[Fertility deity]] * [[Natural fertility]] * [[Reproductive health]] * [[Total fertility rate]] ==References== <references/> *[http://www.preventinfertility.info International Agency for Prevention of Infertility (IAPI) ] ==Further reading== * Bock, J. (2002). Evolutionary Theory and the Search for a Unified Theory of Fertility. ''American Journal of Human Biology 14(2)'' 145-148. [http://anthro.fullerton.edu/jbock/BockIntroAJHB.pdf Full text] {{Reproductive physiology}} [[Category:Fertility|*]] [[Category:Demography]] [[ca:Fertilitat]] [[cs:Plodnost (rozcestník)]] [[da:Frugtbarhed]] [[de:Fruchtbarkeit]] [[es:Fertilidad]] [[eo:Fekundeco]] [[fr:Fertilité]] [[it:Fertilità]] [[lt:Vaisingumas]] [[nl:Vruchtbaarheid]] [[no:Fertilitet]] [[nn:Grøde]] [[pl:Płodność]] [[pt:Fertilidade]] [[ru:Фертильность]] [[simple:Fertility]] [[sr:Фертилитет]] [[fi:Hedelmällisyys]] [[sv:Fertilitet]]