The average age of a girls first period (menarche) is 12–13 (12.5 years in the United States, 12.72 in Canada, 12.9 in the UK), but, in postmenarchal girls, about 80% of the cycles are anovulatory in the first year after menarche, 50% in the third and 10% in the sixth year. A womans fertility peaks in the early and mid 20s, after which it starts to decline, with this decline being accelerated after age 35. However, the exact estimates of the chances of a woman to conceive after a certain age are not clear, with research giving differing results. The chances of a couple to successfully conceive at an advanced age depend on many factors, including the general health of a woman and the fertility of the male partner. Menopause typically occurs between 44 and 58 years of age. DNA testing is rarely carried out to confirm claims of maternity at advanced ages, but in one large study, among 12,549 African and Middle Eastern immigrant mothers, confirmed by DNA testing, only two mothers were found to be older than fifty; the oldest mother being 52.1 years at conception (and the youngest mother 10.7 years old). Tobacco smoking
Tobacco smoking is harmful to the ovaries, and the degree of damage is dependent upon the amount and length of time a woman smokes or is exposed to a smoke-filled environment. Nicotine and other harmful chemicals in cigarettes interfere with the bodys ability to create estrogen, a hormone that regulates folliculogenesis and ovulation.
It is recommended that a consultation with a fertility specialist should be made earlier if the woman is aged 36 years or over, or there is a known clinical cause of infertility or a history of predisposing factors for infertility. According to the World Health Organization (WHO), infertility can be described as the inability to become pregnant, maintain a pregnancy, or carry a pregnancy to live birth. A clinical definition of infertility by the WHO and ICMART is "a disease of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse." Infertility can further be broken down into primary and secondary infertility. Primary infertility refers to the inability to give birth either because of not being able to become pregnant, or carry a child to live birth, which may include miscarriage or a stillborn child. Secondary infertility refers to the inability to conceive or give birth when there was a previous pregnancy or live birth. Prevention
Acquired female infertility may be prevented through identified interventions:

Maintaining a healthy lifestyle. Excessive exercise, consumption of caffeine and alcohol, and smoking have all been  associated with decreased fertility. Eating a well-balanced, nutritious diet, with plenty of fresh fruits and vegetables, and maintaining a normal weight, on the other hand, have been associated with better fertility prospects. Treating or preventing existing diseases. Identifying and controlling chronic diseases such as diabetes and hypothyroidism increases fertility prospects.