If you've been trying to conceive for more than a year, there's a good chance that something may be interfering with your efforts to have a child. Infertility, also known as subfertility, is the inability to conceive a child within one year. Infertility may be due to a single cause in either you or your partner, or a combination of factors that may prevent a pregnancy from occurring or continuing.

Infertility differs from sterility. Being sterile means you're unable to conceive a child. With sterility, you or your partner has a physical problem that precludes the ability to conceive. A diagnosis of infertility simply means that becoming pregnant may be a challenge rather than an impossibility.

In general, don't be concerned about infertility unless you and your partner have been trying regularly to conceive for at least one year. However, if you plan to conceive and you're a woman older than 30 or haven't had a menstrual flow for longer than six months, seek a medical evaluation. If you have a history of irregular or painful menstrual cycles, pelvic pain, endometriosis, pelvic inflammatory disease (PID) or repeated miscarriages, schedule a consultation with your doctor sooner. If you're a man with a low sperm count or a history of testicular, prostate or sexual problems, consider seeking help earlier.