Fertility is an ongoing process that begins at birth. When a girl is born, she typically has between 1 and 2 million eggs in her ovaries. By the time a girl enters puberty, she has 300,000 to 500,000 eggs. Typically, a woman will release a mature egg during her monthly cycle usually between Day 11 - Day 21 of their cycle, counting from the first day of the last menstrual period (LMP). This is what many refer to as the "fertile time" of a woman's cycle, because sexual intercourse during this time increases the chance of pregnancy. Ovulation can occur at various times during a cycle, and may occur on a different day each month. If the egg is successfully fertilized, a pregnancy results. Infertility does not mean that it is impossible to get pregnant.
Typically, experts will treat a couple for infertility that is not able to get pregnant after at least one year of trying to do so. A woman that is able to get pregnant and then has repeat miscarriages may also be treated for infertility. According to the National Center for Health Statistics, in 2002, about 12 percent of women (7.3 million) in the United States aged 15 to 44 had difficulty getting pregnant or carrying a baby to term.
Trouble conceiving is also associated with perimenopause. Read more about pregnancy and the menopausal transition here.
In many healing sciences, infertility is not considered a condition. Rather, it is considered an imbalance in the body that once corrected, will result in conception and pregnancy.