Fertility is the natural capability of giving life. Human fertility rely 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.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.
Age also plays a role, especially for women.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. Women's fertility peaks around the age of 23-24, and often deteriorates after 30. With a rise in women postponing pregnancy, this can create an infertility problem. About 9 percent of recognised pregnancies for women aged 20 to 24 ended in miscarriage. Cervical Mucus is one of the most important indicators of fertility because it changes throughout the menstrual cycle from being dry, thick or pasty (infertile) to being wet and slippery (fertile). The risk rose to about 20 percent at age 35 to 39, and more than 50 percent by age 42".
Male fertility does not decline as it does with females; there have been examples of males being fertile at 94 years old. At most, age "might possibly result in a moderate decline" in fertility in males. Sperm count declines slightly with age, with men aged 50-80 years producing sperm at an average rate of 75% compared with men aged 20-50 years. Infertility is just as likely to be related to male factors as female factors. About 85% to 90% of infertility can be treated with conventional therapies, such as medication or surgery .Fertility drugs are often the first treatment for women who aren't ovulating. Drugs are also used as part of other more complicated assisted reproduction treatments, such as in vitro fertilisation and intrauterine insemination.
