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Infertility in women

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of female infertility.

Alternative Names

Pelvic inflammatory disease; Polycystic ovaries

Causes

Causes of infertility can be found in about 90% of infertility cases but, despite extensive tests, about 10% of couples will never know why they cannot conceive. Between 10 - 30% of cases of infertility have more than one cause. Male or female infertility each account for about 30 - 40% of cases. In men, sperm defects (their quality and quantity) are usually responsible. Female infertility is more complex.

Pelvic Inflammatory Disease

Pelvic inflammatory disease (PID) is the 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 PIDs). 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 (a growing global problem as tuberculosis cases increase)
• Nonsterile abortions
• Ruptured appendix
• Herpesvirus (suggested for some cases, but not confirmed as a cause).

Symptoms of PID. The infection may be subclinical (occurring without any symptoms), or there may be fever, chills, or pelvic pain indicating inflammation of the entire pelvic area.

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. Some evidence suggests that between 30 - 50% of women with endometriosis are infertile. Often, however, it is difficult to determine if endometriosis is the primary cause of infertility, particularly in women who have mild endometriosis. Endometriosis rarely causes an absolute inability to conceive, but, nevertheless, it can contribute to it both directly and indirectly.

Direct Effect of Endometrial Cysts. Endometrial cysts may directly 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.

Immune Factors and the Inflammatory Response. Researchers are focusing on defects in the immune system that not only may be responsible for endometriosis in the first place but may also cause the infertility associated with endometriosis. Even in early stage endometriosis, investigators have observed increased immune system activity.

Other Conditions Linking Endometriosis and Infertility. Researchers have sometimes noted unusually low levels of specific substances that enable a fertilized egg to adhere to the uterine lining. (Such abnormalities are more often a factor in infertility in women with mild to moderate endometriosis than in those with severe cases.)

One study found that the eggs in women with endometriosis appeared to have more genetic abnormalities than those in women without the disorder.

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. According to a 2002 study, nearly 30% of obese women with PCOS had amenorrhea. (The rate was lower -- 4.7% -- in women with normal weight.)

In PCOS, increased androgen production produces high LH levels and low 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, so 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. Other male characteristics, such as deepening voice and clitoral enlargement, are rare.

PCOS also poses a high risk for insulin resistance, particularly in women who are also obese. Insulin resistance is associated with diabetes type 2, in which insulin levels are normal or high but the body cannot use this hormone efficiently. About half of PCOS patients, in fact, also have diabetes.

Premature Ovarian Failure (Early Menopause)

Premature ovarian failure (POF) 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. There are numerous causes of POF. Often the cause of this disorder or other causes of POF is unknown. In some cases, POF may represent an acceleration of the aging process.

The following conditions may produce POF:

• Adrenal, pituitary, or thyroid gland deficiencies.
• Genetic factors related to the X chromosome. A woman needs two functioning X chromosomes for normal reproduction. When one is abnormal, ovarian function fails. The most severe example is Turner's syndrome, a genetic condition, in which one of the two X-chromosomes is missing or malfunctioning. Milder cases of ovarian failure can occur in fragile X syndrome and other rare inherited conditions that cause partial X-chromosome abnormalities.
• Cancer treatments (radiation, chemotherapy, or both). Women who are undergoing cancer treatments and who want to become pregnant should see a reproductive specialist to discuss their options. According to the American Society of Clinical Oncology’s 2006 guidelines, the fertility preservation method with the best chance of success is embryo cryopreservation. This procedure involves harvesting a woman’s eggs (oocytes), followed by in vitro fertilization and freezing of embryos for later use. Other treatments under investigation include egg preservation, collecting and freezing unfertilized eggs, removing and freezing a part of the ovary for later reimplantation, and using hormone therapy to protect the ovaries during chemotherapy. Women may be able to access these investigational approaches through enrolling in clinical trials.
• Autoimmunity. Autoimmune diseases, including diabetes type 1, systemic lupus erythematosus, autoimmune hypothyroidism, and autoimmune Addison's disease, are associated with a higher risk for early menopause. Autoimmunity, however, may also play a role in some cases of POF without the presence of specific autoimmune diseases. In such cases, antibodies specifically attack the cells that secrete reproductive hormones thus causing ovarian failure.
• Other causes of POF include sarcoidosis, mumps, some sexually transmitted diseases, and tuberculosis. Women with epilepsy are at higher risk for POF.

Idiopathic Hypogonadotropic Hypogonadism

Idiopathic hypogonadotropic hypogonadism is a rare condition in which follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are underproduced and prevent the development of functional ovaries. There are no other abnormalities in the hypothalamus-pituitary axis (such as tumors or abnormal stress hormones or prolactin). In most cases, the causes of hypergonadotropic hypogonadism are unknown. Genetic factors, including Kallman's syndrome, have been identified in about 20% of these cases.

Functional Hypothalamic Amenorrhea (FHA) and Eating Disorders

Functional hypothalamic amenorrhea (FHA) is the absence of menstruation due to disturbances in the thyroid gland and hypothalamus-pituitary-adrenal (HPA) system, which regulates reproduction and other important functions. The eating disorders anorexia and bulimia are most often associated with FHA. FHA may be due to other different factors, most unknown.

Luteal Phase Defect (Implantation Failure)

Luteal phase defect is a general term referring to problems in the corpus luteum that result in inadequate production of progesterone. Because progesterone is necessary for thickening and preparing the uterine lining, the ovum fails to successfully implant in the endometrium. Between 25 - 60% of women who experience recurrent miscarriages may have a luteal phase defect. A luteal phase defect, however, can also occur in fertile women, so other factors may be responsible for implantation failure.

Benign Uterine Fibroids

Benign fibroid tumors in the uterus are extremely common in women in their 30s. The effect of fibroids on fertility is controversial. A 2002 analysis suggested that they may account for infertility in only 1 - 2.4% of women who are having trouble conceiving.

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.

Some evidence suggests that even small fibroids may reduce the chances of pregnancy in women who are undergoing assisted reproductive techniques. Treatments to reduce fibroids may be helpful in such women, although there has been little research on this subject.

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. (These are benign tumors that secrete prolactin. They can cause headache and visual problems as well as breast secretions.) 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 ) is 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's 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. Laparoscopic surgery is less likely to cause adhesions than standard open surgery.

In some of these cases, surgery may be helpful. One technique, called pressure lavage under ultrasound guidance (PLUG), may prove to be useful for treating some cases of mild scarring in the uterus (intrauterine adhesions). This technique is based on transvaginal sonohysterography, which uses ultrasound along with saline infused into the uterus to enhance visualization. Continuous accumulation of saline in the procedure is used to break up the scars.

Other Causes of Infertility

Ectopic Pregnancies. Ectopic pregnancies increase the risk for infertility, although subsequent pregnancy rates are quite variable. Ectopic pregnancies that terminate without treatment appear to pose a lower risk for future infertility. Even a ruptured tube does not appear to reduce the chance for a future pregnancy in most women. Such an event however can be dangerous and even life threatening for the woman. Laparoscopic surgery to remove a fallopian tube affected by an ectopic pregnancy may preserve fertility better than traditional abdominal surgery.

Medications. Among the medications that can cause temporary infertility are those used to treat chronic disorders, as well as antidepressants, hormones, pain killers, and antipsychotic drugs.

Inflammatory Bowel Disease. Inflammatory bowel disease (particularly Crohn's disease or surgery for ulcerative colitis) can affect fertility.

Celiac Sprue. Celiac sprue is a disease in which the patient cannot tolerate gluten, a common food chemical. The disorder is also highly associated with infertility in men and women, possibly through multiple effects on nutrition, immune factors, and hormones. The mechanisms are not altogether clear, but infertility is usually reversible with strict dietary control.

Epilepsy. In one study of women with epilepsy, fertility rates were 33% lower than among women in the general population, perhaps due to certain antiepileptic drugs that increase the risk for birth defects. The social effects of epilepsy may also lead to marriage at an older age, which can be associated with delayed attempts to get pregnant and thereby affect fertility.

Thyroid Problems. Thyroid problems, either too much thyroid hormone (hyperthyroidism) or too little (hypothyroidism), can interrupt cycles.

Metabolic Syndrome (also Called Syndrome X). Doctors diagnose this condition when at least three of the the following abnormalities are present:

• Abdominal obesity
• Low HDL (good) cholesterol levels
• High triglyceride levels
• High blood pressure
• Insulin resistance

Metabolic syndrome is a pre-diabetic condition that is significantly associated with heart disease. A 2002 study reported that, as with PCOS, women with metabolic syndrome have higher levels of male hormones and are therefore at risk for infertility. A 2002 study estimated that 24% of the population now has this condition.

Other Medical Conditions. Medical conditions associated with delayed puberty and amenorrhea (absence of periods) include Cushing's disease, sickle cell disease, HIV, kidney disease, and diabetes. Genetic mutations that affect luteinizing hormone may also be responsible for some cases of light or absent menstruation. Other rare genetic disorders, such as Kallman syndrome, cause abnormalities in the hypothalamus of the brain.

• Review Date: 10/19/2006
• Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.

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