Causes of Female Infertility
What Causes Infertility in Women?
Infertility is the inability to get pregnant after twelve consecutive months of unprotected intercourse. Approximately 10 percent of couples in the U.S. are affected by infertility, and one-third of the time, the diagnosis is due to female infertility. For 20 percent of couples, the cause of infertility is never determined. Most cases of infertility can be treated with medication or surgery, and improvements in fertility treatment now make it possible for couples to conceive. The normal reproduction process requires that the woman ovulates to release an egg from one of her ovaries. The egg travels to the uterus via the fallopian tube. After fertilization, the egg implants into the uterine lining. Infertility occurs when something in this pattern does not occur or is altered in some way. Common causes of female infertility include fallopian tube damage and hormonal, cervical, and uterine causes.
Fallopian Tube Damage
Damage to the fallopian tubes can prevent proper interaction between the egg and sperm. Each of the fallopian tubes carries the egg from the ovary to the uterus. Common causes of fallopian tube damage include:
- Pelvic Inflammatory Disease. Called PID, pelvic inflammatory disease is caused by sexually transmitted infections, particularly gonorrhea and chlamydia. These bacteria damage a woman's fallopian tubes, cause vaginal discharge, and lead to pelvic cramping. When the condition is not treated promptly or appropriately, scarring to the fallopian tubes occurs, causing blockage of the tubes. This inhibits the egg from reaching the uterus for fertilization.
- Endometriosis. One condition that contributes to infertility is endometriosis. This causes the uterine tissue to grow outside the uterus, resulting in pelvic pain and scarring of the reproductive structures, especially the fallopian tubes.
- Scarring from pelvic surgery. Many procedures can lead to scarring of the fallopian tubes. With scarring, adhesions develop and block the fallopian tubes. This affects the egg's ability to pass through to the uterus for fertilization and implantation.
Many women who are infertile have problems with ovulation. Synchronized hormonal changes result in the release of an egg from one of the ovaries and cause thickening of the uterine lining (endometrium). When hormones are not in balance, a problem with ovulation is likely to occur. Hormonal problems are detected using basal body temperature monitoring, ovulation testing, and blood testing for hormone levels. Common hormonal causes of female infertility include:
- Polycystic Ovary Syndrome. Often called PCOS, polycystic ovary syndrome is a complex condition where the body produces too much of the male hormone testosterone.
- Hyperprolactinemia. When the body produces too much prolactin, the condition is called hyperprolactinemia. Prolactin is necessary for stimulation of breast milk production.
- Primary ovarian insufficiency. This condition is often called menopause or premature menopause. Primary ovarian insufficiency occurs when the ovaries stop producing the necessary reproductive hormones for ovulation and conception. Certain conditions are associated with early menopause, including radiation therapy, chemotherapy, smoking, and immune system diseases.
- Thyroid dysfunction. When the thyroid gland produces too much thyroid hormone (hyperthyroidism) or too little (hypothyroidism), it can interrupt the menstrual cycle and lead to infertility.
A small percentage of women with infertility have a cervical condition where the sperm cannot pass through the cervix opening into the uterus. Common cervical causes of female infertility include:
- Abnormal cervical mucus. The preovulatory cervical mucus can affect fertility. Sperm cannot live in an acidic environment where the pH is lower than 7.2. The cervical mucus pH depends on the hormonal environment. Suboptimal mucus conditions include thick and viscous mucus that limits sperm penetration, low mucus pH which destroys or weakens sperm, antisperm antibodies which inactivate the sperm, and infection of the cervix which causes inflammatory cells that digest the sperm.
- Prior cervical surgery. Certain cervical procedures can damage the cervical os (opening to the uterus) and make it less compliant. When a woman has cervical cancer, it is often necessary to be treated by biopsies, conization, and/or cryotherapy. Scarring and adhesions to the cervix can inhibit the passage of sperm.
A small group of women develop uterine growths that can interfere with fertility. Common uterine causes of female infertility include:
- Uterine polyps. Benign growths in the uterus are often referred to as uterine polyps. These small tumors can adhere to the wall of the uterus and block the fallopian tubes, inhibiting the egg from traveling to its destination. When uterine polyps block the cervical opening, sperm cannot pass through to fertilize the egg.
- Uterine fibroids. Fibroids in the uterus distort the uterine cavity and interfere with implantation of a fertilized egg. These benign tumors could also block the fallopian tubes, permitting the egg from passing into the uterus.
In around 20 percent of couples, the actual cause of infertility is not determined. However, there are several risk factors that put a woman at risk for infertility. These include:
- Environmental factors. This includes smoking cigarettes, use of marijuana, heroin, cocaine, and methamphetamines, and drinking alcohol.
- Extreme weight loss or gain. These factors can disrupt normal ovulation and hormone levels.
- Excessive exercise. Many women who over exercise have problems with ovulation and conception.
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