There are many causes of infertility, and issues regarding infertility that can be related to either female factors (present in about 35% of infertile couples), male factors (present in another 35% of infertile couples), a combination of male and female factors (present in 20% of couples) or it can completely unexplained (10% of cases).
Female Factor Infertility
Maternal age seems to be one of the most obvious causes of infertility in women. Women are born with all of the eggs they will ever have – females do not produce more eggs as they age. Female fertility peaks at in the mid to late 20s and maternal age older than 35 is a significant cause of infertility in females.
Ovulatory difficulties represent another cause of infertility in women, and women who only ovulate sporadically have a more difficult time getting pregnant. Ovulatory difficulties can be related to high stress levels, drastic weight loss or gain, excessive exercise or anorexia and hormone imbalances. Additionally, one common disorder (called PCOS or polycystic ovarian syndrome) can be a cause of infertility that is directly attributable to ovulation difficulties. Women who suffer from this disease have multiple cysts on their ovaries that interfere with ovulation.
Besides ovulatory difficulties, female factor infertility can result from “structural” issues with the female’s anatomy. Problems with the uterus can prevent implantation of a fertilized egg. These can include a bifurcated uterus, where the uterine wall is misshapen, polyps or cysts in the uterus. Cervical mucous, which facilitates the sperm’s journey to the egg can also be a cause of infertility. “Hostile” cervical mucous can occur naturally, can (ironically enough) occur because of fertility drugs and can also result from an allergic reaction to sperm. Finally, scar tissue that results from previous trauma, sexually transmitted diseases, abdominal surgery or a disease called endometriosis, is another cause of infertility in women.
Male factor infertility
Infertility in men is usually attributable to problems with the number or quality of sperm produced. Unlike women, men constantly produce fresh sperm, thus paternal age is relatively limitless and men have been known to conceive well into their 70s. Male factor causes of infertility are related to stress, genetic disorders that affect how sperm is produced, issues with varicose veins in the testes, and autoimmune disorders in which men produce antibodies against their own sperm. Additionally, high scrotal temperatures (associated with varicose veins, wearing tight underwear, and regular use of hot tubs or saunas) are a major cause of infertility in men.