What Causes Infertility?

Note:  This Article first published in Ezines.

Pregnancy is the result of a chain of events. A woman must release an egg from one of her ovaries (ovulation). The egg must travel through a fallopian tube toward her uterus. A man’s sperm must join with (fertilize) the egg along the way. The fertilized egg must then become attached to the inside of the uterus. While this process may seem simple, in fact many things can happen along the way to prevent pregnancy. As a result there are a lot of conditions that may be reasons for infertility. Some of them are simple while others may be quite complicated. It’s important to remember too that infertility can occur because of a problem with the female or with the male. Some cases of infertility involve a mix of both female and male factors.

An Overview of Female Factor Reasons for Infertility

Problems with Ovulation

For women, the most common reason for infertility is some sort of ovulation problem. Without ovulation, eggs are not available for fertilization. Problems with ovulation are signaled by irregular menstrual periods or a lack of periods altogether (called amenorrhea or anovulation). The normal ovarian cycle is so complex that even small changes may disrupt the cycle and prevent ovulation. In most cases, hormonal imbalances, like not having enough of a certain hormone or not releasing a hormone at the right time, are the cause of the problem. Extremely low body weight, being overweight, or any rapid and dramatic change in weight (loss or gain) can cause such imbalances. A hormonal imbalance may mean that the woman does not ovulate regularly or at all. Simple lifestyle factors such as dieting or athletic training can affect a woman’s hormonal balance. In other circumstances, a hormonal imbalance can result from a medical problem such as a pituitary gland tumor, hypothyroidism, or Polycystic Ovarian syndrome (PCOS). PCOS is in fact the most common cause of anovulation — when a woman has PCOS, cysts appear on the ovaries and the ovaries themselves may increase in size, resulting in irregular or absent menstrual periods.

Luteal Phase Defect

Another hormonal condition that is a common cause of infertility is known as a luteal phase defect (LPD). The luteal phase is the time in the menstrual cycle between ovulation and the start of the next menstrual period. LPD is a failure of the uterine lining to be fully prepared for a fertilized egg to implant there. This happens either because a woman’s body is not producing enough progesterone, or because the uterine lining isn’t responding to progesterone levels. Since pregnancy depends on a fertilized egg implanting in the uterine lining, LPD can interfere with a woman getting pregnant and with carrying a pregnancy successfully.

Ovarian Reserve

A woman’s ovarian reserve is shorthand for the number and quality of eggs in her ovaries and how well her follices respond to the hormones in her body that should trigger ovulation. As a woman approaches menopause, her ovaries don’t respond as well to hormones, and in time they may not release any eggs. While a reduced ovarian reserve is natural as a woman ages, young women might have reduced ovarian reserves as well due to smoking, a prior surgery on their ovaries, or a family history of early menopause.

Blocked fallopian tubes

Sometimes a woman’s fallopian tubes become blocked because of past infections (pelvic inflammatory disease, for example), or abdominal surgery. Sexually transmitted diseases can also scar or damage the fallopian tubes, causing blockages. Such blockages can interfere with the sperm and egg uniting. If the sperm does manage to reach an egg within the fallopian tube and fertilize it, a blockage can still prevent the embryo from travelling down to implanting itself in the uterus. Often women with blocked fallopian tubes don’t experience any symptoms.

Cervical disorders

When a woman isn’t ovulating, cervical mucus helps prevent infections entering the uterus. During ovulation, the thickness and quality of the mucus alters to allow sperm to pass through. Sometimes cervical problems prevent this thinning out of the cervica mucus during ovulation, preventing the sperm from reaching the egg.

Uterine Disorders

Fibroids are tumors in the uterus that can cause infertility in a woman. Other anatomic anomalies in the uterus such as an abnormal uterine lining may also be reasons for infertility.

Endometriosis

Endometriosis has also been linked to female infertility. In a woman with this disorder, tissue that normally resides in the uterus is found attached to other internal organs, such as the ovaries. Endometriosis has been found to be a cause of infertility in over one-third of cases where no other reason for the lack of ability to conceive was found. Once again, surgery may be performed to treat this condition.

An Overview of Male Factor Reasons for Infertility

The primary reason for male factor infertility is a sperm disorder. Of the millions of sperm normally deposited into the vagina, only a few hundred will get close to the egg and have a chance to fertilize it. Many factors play a role in determining whether or not the sperm will succeed.

Sperm Count

While by definition, a low sperm count is as having less than 20 million sperm per ml of seminal fluid, there are several factors that collectively determine the adequacy of “sperm count,” including (1) the total number of sperm in a sample, (2) the number of sperm per milliliter of semen and (3) the volume of semen the man produces. A deficiency in any of these three factors can have the effect of a low sperm count. Often the cause of a low sperm count is unknown. Sometimes low sperm count is attributable to a varicocele, or varicose vein in a man’s testicles. The swollen vein leads to a higher body temperature in that area, which in turn causes decreased sperm production and less mobility for the sperm that are produced.

Quality of Sperm

Although sperm count is important, sperm motility and forward progression (i.e., the number of sperm with the ability to move and the quality of that movement) appear to be even more crucial in determining the likelihood of whether or not the sperm will succeed in fertilizing the egg. Despite a low sperm count, many men with high-quality sperm may still be fertile. Sperm that is abnormal in shape may also be a reason for male infertility.

Cause of Sperm Disorders

Sperm disorders can be caused by a variety of issues, including (1) age — generally, a man’s fertility starts declining at around the age of 35 as the quality of a man’s sperm diminishes, (2) Immune disorders that can cause a man’s body to treat sperm as if it were a foreign matter, (3)sexually transmitted diseases (STDs) that may damage the parts of the body that transport sperm through the reproductive tract and (4) lifestyle and environmental factors such as overuse of alcohol, nicotine, marijuana, and prescribed or non-prescribed drugs.