PHYSICAL ABNORMALITIES CAUSING INFERTILITY IN WOMEN

Most of the physical abnormalities listed here are internal and may not be apparent to the average woman. They can prevent women in some way from getting pregnant. Sometimes referred to as organic pelvic disease, structural problems in a woman's reproductive organs can be caused by a variety of factors, such as endometriosis, infection, congenital defects, inflammation, trauma, tumors and disease.

a) Endometriosis

The lining of the uterus is called the endometrium. Endometriosis refers to the build-up of endometrial tissue outside the uterus. The most widely accepted (but not proven) theory for its cause is that menstrual blood flows out of the fallopian tubes instead of down through the vagina. Endometriosis can cause painful, heavy periods and pain during intercourse, but can also present no symptoms at all, except infertility.

Endometriosis can impact the ability to achieve pregnancy in several ways:

• Tissue overgrowth can occur on the fallopian tubes, the outside of the uterus, or the ovaries. The overgrowths can cause obstructions or distortions that can impair a woman’s ability to become pregnant.
• The endometrial tissue may release toxic substances that reduce the egg's potential to be fertilized. A minimal amount of excess endometrial tissue might merely diminish the capacity for fertilization, not necessarily eliminate it.

b) Occluded fallopian tubes

Fallopian tubes play a crucial role in the female reproductive process, functioning as the pathway between the ovaries and the uterus. Tubal scarring or blockage can prevent the egg from reaching the uterus and prohibit the sperm from accessing the egg. Blockages in the fallopian tubes are usually the result of a sexually transmitted disease (STD), scarring from pelvic surgery or pelvic inflammatory disease (PID), or from endometriosis. It may still be possible to get pregnant if only one tube is blocked.

c) Ovarian scarring

Scarring of the ovaries can trap the eggs inside the ovary. Ovarian scarring can be the result of PID, an infection, endometriosis or surgery. If the scarring causes the ovaries to be oddly placed, it might be hard for the fimbriae (finger-like projections at the end of the fallopian tubes) to gather the released eggs and move them into the fallopian tubes. The medical term for scarring is "adhesion". Adhesions may account for about 15-25% of female causes of infertility.

Polycystic ovaries can have a thickened outer coating or capsule that may prevent the egg from ovulating as well.

d) Uterine abnormalities

Abnormalities in the shape or position of the uterus will most likely not prevent fertilization, but can prevent the ability for an embryo to implant or for the pregnancy to carry to term. Some women are wrongly diagnosed as infertile when their uterus is abnormal. These conditions can be found in (but are not limited to) women whose mothers took the antimiscarriage drug diethylstilbestrol (DES).

Abnormalities include:

Malposition: The uterus may be sinking into the vaginal canal (prolapsed).

Growths: Fibroid tumors (benign growths that form on the uterus wall) and polyps (bunched up endometrial tissue) can prevent the healthy development of the embryo.

Bicornuate uterus: The uterus is divided into two chambers, divided by a septum (wall of tissue).

Unicornuate uterus: The uterus is one-sided.

Asherman syndrome: Scarring (adhesions) of the interior of the uterus that can occur after uterine surgery or, more rarely, infection.

Certain infections experienced by women have been known to affect fertility, for example, autoimmune diseases such as thyroiditis, diabetes mellitus or pernicious anemia. Some which are:

• Abdominal disease
• Cancer
• Pelvic inflammatory disease (PID)
• Sexually transmitted diseases (STDs)
• Stress

For women, fertility peaks in their early 20s, and declines dramatically after age 35. The greatest impact that age has on female fertility is a decrease in the quantity and quality of their eggs. As a woman ages, the risk of producing a chromosomally abnormal egg increases. Many of these abnormal eggs never make it to fertilization or implantation. If pregnancy does occur there is a higher incidence of miscarriage.

The number of eggs declines to approximately one million by the time of birth, and further declines to about 300,000 by the time a woman enters puberty. The gradual decline continues throughout her reproductive life. Many eggs start the developmental process every month, but the majority of those will stop developing and only one or two eggs will ovulate. Eventually a woman will exhaust her supply of eggs, cease having spontaneous menstrual cycles and become menopausal.

A significant deviation from normal body weight, whether overweight or underweight, can cause infertility in both men and women. In fact, one study suggests that 12% of primary infertility is due to weight issues.

Underweight

For women, low weight can decrease production of GnRH. This can cause ovulation to become irregular or even stop. Decreased GnRH levels can affect the development of the uterine lining and its receptivity to the implanting embryo. For men, low weight could lead to decreased sperm count or function.

Overweight

Being overweight can also lead to an abnormal hormonal signal, impacting ovulation and possibly sperm production. It can cause an overproduction of insulin, which may cause irregular ovulation. There is a link between obesity, excess insulin production and the infertility condition known as polycystic ovarian syndrome (PCOS).