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.
Pelvic exam, to look for abnormalities or infection. A postcoital test, which is done soon after intercourse to check for problems with sperm surviving in cervical mucous (not commonly used now because of test unreliability). Hysterosalpingography or sonosalpingography, to check for tube patency
Sonohysterography to check for uterine abnormalities.There are genetic testing techniques under development to detect any mutation in genes associated with female infertility.Initial diagnosis and treatment of infertility is usually made by obstetrician/gynecologists or womens health nurse practitioners. If initial treatments are unsuccessful, referral is usually made to physicians who are fellowship trained as reproductive endocrinologists. Reproductive endocrinologists are usually obstetrician/gynecologists with advanced training in reproductive endocrinology and infertility (in North America). These physicians treat reproductive disorders affecting not only women but also men, children, and teens. Usually reproductive endocrinology & infertility medical practices do not see women for general maternity care. The practice is primarily focused on helping their women to conceive and to correct any issues related to recurring pregnancy loss. Definition
There is no unanimous definition of female infertility, because the definition depends on social and physical characteristics which may vary by culture and situation. NICE guidelines state that: "A woman of reproductive age who has not conceived after 1 year of unprotected vaginal sexual intercourse, in the absence of any known cause of infertility, should be offered further clinical assessment and investigation along with her partner."