Causes:

Numerous medical conditions can contribute to infertility. In fact, most cases of infertility are due to other medical conditions. These disorders can damage the fallopian tubes, interfere with ovulation, or cause hormonal complications.

Some of the main medical conditions associated with infertility follow.

Pelvic Inflammatory Disease

Pelvic inflammatory disease (PID) is a major cause of female infertility worldwide. PID comprises a variety of infections caused by different bacteria that affect the reproductive organs, appendix, and parts of the intestine that lie in the pelvic area. The sites of infection most often implicated in infertility are in the fallopian tubes, a specific condition referred to as salpingitis.

Causes of PID. PID may result from many different conditions that cause infections. Among them are:

• Sexually transmitted diseases (cause of most PID). Chlamydia trachomatis is an infectious organism that causes 75% of infertility in the fallopian tubes. Gonorrhea is responsible for most of the remaining cases.
• Pelvic tuberculosis
• Nonsterile abortions
• Ruptured appendix

Effects of PID. Severe or frequent attacks of PID can eventually cause scarring, abscess formation, and tubal damage that result in infertility. About 20% of women who develop symptomatic PID become infertile. PID also significantly increases the risk of ectopic pregnancy (fertilization in the fallopian tubes). The severity of the infection, not the number of the infections, appears to pose the greater risk for infertility.

Endometriosis

Endometriosis may account for as many as 30% of infertility cases. Endometriosis rarely causes an absolute inability to conceive, but, nevertheless, it can contribute to it both directly and indirectly.

Endometriosis is a noncancerous condition in which cells that normally line the uterus (endometrium) also grow on other areas of the body, causing pain and irregular bleeding.

Endometrial cysts may cause infertility in several ways:

• If implants occur in the fallopian tubes, they may block the egg's passage.
• Implants that occur in the ovaries prevent the release of the egg.
• Severe endometriosis can eventually form rigid webs of scar tissue (adhesions) between the uterus, ovaries, and fallopian tubes, thereby preventing the transfer of the egg to the tube.

[For more information, see In-Depth Report #74: Endometriosis.]

Polycystic Ovarian Syndrome

Polycystic ovarian syndrome (PCOS) is a condition in which the ovaries produce high amounts of androgens (male hormones), particularly testosterone. PCOS occurs in about 6% of women, and amenorrhea or oligomenorrhea (infrequent menses) is quite common.

In PCOS, increased androgen production produces high luteinizing hormone (LH) levels and low follicle-stimulating hormone (FSH) levels, so that follicles are prevented from producing a mature egg. Without egg production, the follicles swell with fluid and form into cysts. Every time an egg is trapped within the follicle, another cyst forms and the ovary swells, sometimes reaching the size of a grapefruit. Without ovulation, progesterone is no longer produced, whereas estrogen levels remain normal.

The elevated levels of androgens (hyperandrogenism) can cause obesity, facial hair, and acne, although not all women with PCOS have such symptoms. PCOS also poses a high risk for insulin resistance, which is associated with type 2 diabetes. About half of PCOS patients also have diabetes.

Premature Ovarian Failure (Early Menopause)

Premature ovarian failure is the early depletion of follicles before age 40, which, in most cases, leads to premature menopause. It affects about 1% of women and is typically preceded by irregular periods, which might continue for years. In this condition, follicle-stimulating hormone (FSH) levels are elevated, as they are during perimenopause. Premature ovarian failure is a significant cause of infertility, and women who have this condition have only a 5 - 10% chance to conceive without fertility treatments.

Causes of premature ovarian failure include:

• Adrenal, pituitary, or thyroid gland deficiencies
• Genetic disorders, such as Turner syndrome and fragile X syndrome
• Cancer treatments (radiation, chemotherapy, or both)
• Autoimmune disorders (such as type 1 diabetes, systemic lupus erythematosus, autoimmune hypothyroidism, Addison's disease) are associated with a higher risk for early menopause

Uterine Fibroids

Benign fibroid tumors in the uterus are extremely common in women in their 30s. Large fibroids may cause infertility impairing the uterine lining, by blocking the fallopian tube, or by distorting the shape of the uterine cavity or altering the position of the cervix. [For more information, see In-Depth Report #73: Uterine fibroids.]

Elevated Prolactin Levels (Hyperprolactinemia)

Prolactin is a hormone produced in the pituitary gland that stimulates breast development and milk production in association with pregnancy. High levels of prolactin (hyperprolactinemia) reduce gonadotropin hormones and inhibit ovulation. Hyperprolactinemia in women who are not pregnant or nursing can be caused by hypothyroidism or pituitary adenomas. (Pituitary adenomas are benign tumors that secrete prolactin.) Some drugs, including oral contraceptives and some antipsychotic drugs, can also elevate levels of prolactin.

Secretions from the breast not related to pregnancy or nursing (called galactorrhea) are a telltale symptom of high prolactin levels and should be investigated.

Structural Problems Causing Obstruction

Inborn Abnormalities. Inborn genital tract abnormalities may cause infertility. Mullerian agenesis is a specific malformation in which no vagina or uterus develops. Even in these cases, some women can become mothers by undergoing in vitro fertilization and having the fertilized egg implanted in another woman who is willing and able to carry the pregnancy (a surrogate mother).

Uterine or Abdominal Scarring. Bands of scar tissue that bind together after abdominal or pelvic surgery or infection (called adhesions) can restrict the movement of ovaries and fallopian tubes and may cause infertility. Asherman syndrome, for example, is scarring in the uterus that can cause obstructions and secondary amenorrhea. It may be caused by surgery, repeated injury, or unknown factors.