Fertility is the ability of people or animals to produce healthy offspring in abundance. In the English language, the term was originally applied only to females, but increasingly is applied to males as well, as common understanding of reproductive mechanisms increases and the importance of the male role is better known. The opposite of fertility is infertility.
Human fertility depends on factors of nutrition, sexual behavior, culture, instinct, endocrinology, timing, economics, way of life, and emotions. Animal fertility is no less complex, and may display astounding mechanisms.
Fertility is also applied to farmlands and plants, where it implies a capacity to yield large crops of sound fruits, seeds or vegetables.
The fertility rate is a 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 number of women themselves 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.
Both women and men have hormonal cycles which determine both when a woman can achieve pregnancy and when a man is most fertile. The female cycle is approximately twenty-eight days long, but the male cycle is variable.
Women ovulate at about the fourteenth day of their cycle, this obviously being the most fertile time for females.
Men can ejaculate and produce sperm at any time of the month, but their libido dips occasionally, which scientists guess is in relation to their internal cycle.
During the fourteenth week of fetal growth, a womenšs eggs (or ova) form in her ovaries, where they will remain until puberty.
At puberty, the eggs will eventually start to mature one-by-one. At ovulation, the egg bursts from the ovary sometimes causing a small, sharp pain called mittelschmerz. If the egg is not fertilized by the malešs sperm, the egg will break down within twenty-four hours into its components (mostly protein) and be reabsorbed by the body.
New technique opens fertility treatment to thousands of women Guardian - July 2, 2007
First baby from lab-matured egg BBC - July 2, 2007
Key to Male Infertility Found Live Science - July 1, 2007
Babies reach out in the womb News in Science - February 5, 2007
Non-invasive Down's syndrome test shows promise New Scientist - February 2, 2007
New IVF technique triples success rate Guardian - February 1, 2007
Why fat is a fertility issue New Scientist - February 3, 2007
Parents Pick Sex of Child in New Clinical Trial Live Science - October 27, 2005
Fertility in middle age linked with anti-ageing New Scientist - June 21, 2005
Fertility Study Looks At Ovulation's Intricate Working Science Daily - June 22, 2005
Women diagnosed with cancer can produce healthy offspring Pravda - May 21, 2005
Scientists are developing artificial wombs, sperm and eggs Guardian - May 19, 2005
Parents 'could pick babies' sex' BBC - March 2005
4-D Ultrasound Gives Video View of Life in the Womb National Geographic - February 2005
Eggs 'fertilized' without sperm BBC - December 2004
'Ovary-arm' transplant a success BBC - November 2004
A woman undergoing cancer treatment has had her fertility
saved after doctors transplanted her ovary into her arm.
Scans uncover secrets of the womb BBC - June 2004
A new type of ultrasound scan has produced the first vivid
pictures of a 12 week-old fetus "walking" in the womb.
First pregnancy from frozen ovaries New Scientist - June 2004
Mice created without fathers BBC - April 2004
Scientists have created two female mice
without fertilizing the eggs they grew from.
'Virgin birth' mammal rewrites rules of biology New Scientist - April 2004
A mammal that is the daughter of two female parents
has been created for the first time.
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