Primary infertility is the term used to describe a couple that has never been able to conceive a pregnancy, after a minimum of 1 year of attempting to do so through unprotected intercourse. Secondary infertility is the term used to describe couples who have previously been pregnant at least once, but have not been able to achieve another pregnancy. Causes of infertility include a wide range of physical as well as emotional factors. Approximately 30% to 40% of all infertility is due to a "male" factor, such as retrograde ejaculation, impotence, hormone deficiency, environmental pollutants, scarring from sexually transmitted disease, or decreased sperm count. Some factors affecting sperm count are heavy marijuana use or prescription drugs, such as cimetidine, spironolactone, and nitrofurantoin. A "female" factor (for example, scarring from sexually transmitted disease or endometriosis, ovulation dysfunction, poor nutrition, hormone imbalance, ovarian cysts, pelvic infection, tumor, or transport system abnormality from the cervix through the fallopian tubes) is responsible for 40% to 50% of infertility in couples. The remaining 10% to 30% may be caused by contributing factors in both partners, or no cause can be adequately identified. It is estimated that 10% to 20% of couples will be unable to conceive after 1 year of attempting to become pregnant. It is important that pregnancy be attempted for an extended period (at least 1 year). The chances for pregnancy occurring in healthy couples who are both under the age of 30, having intercourse regularly, is only 25% to 30% per month. A woman's peak fertility is in her early 20s. As a woman ages beyond 35 (and particularly after age 40), the likelihood of conceiving is less than 10% per month. In addition to age-related factors, increased risk for infertility is associated with having:
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