Infertility is the failure of a couple to conceive a pregnancy after trying to do so for at least one full year. In primary infertility, pregnancy has never occurred. In secondary infertility, one or both members of the couple have previously conceived, but are unable to conceive again after a full year of trying.
(1) Hormonal Problems
These are the most common causes of anovulation.
Failure to produce mature
In approximately 50% of the cases of anovulation, the ovaries do not produce
normal follicles in which the eggs can mature. Ovulation is rare if the
eggs are immature and the chance of fertilization becomes almost nonexistent.
Polycystic ovary syndrome, the most common disorder responsible for this
problem, includes symptoms such as amenorrhoea, hirsutism, anovulation and
infertility. This syndrome is characterized by a reduced production of
FSH, and normal or increased levels of LH, oestrogen and testosterone. The
current hypothesis is that the suppression of FSH associated with this condition
causes only partial development of ovarian follicles, and follicular cysts can
be detected in an ultrasound scan. The affected ovary often becomes
surrounded with a smooth white capsule and is double its normal size. The
increased level of oestrogen raises the risk of breast cancer.
- Malfunction of the hypothalamus
The hypothalamus is the portion of the brain responsible
for sending signals to the pituitary gland, which, in turn, sends hormonal
stimuli to the ovaries in the form of FSH and LH to initiate egg maturation. If
the hypothalamus fails to trigger and control this process, immature eggs will
result. This is the cause of ovarian failure in 20% of cases.
- Malfunction of the pituitary gland
The pituitary's responsibility lies in producing and
secreting FSH and LH. The ovaries will be unable to ovulate properly if either
too much or too little of these substances is produced. This can occur due to
physical injury, a tumor or if there is a chemical imbalance in the pituitary.
(2) Scarred Ovaries
Physical damage to the ovaries may result in failed
ovulation. For example, extensive, invasive, or multiple surgeries, for repeated
ovarian cysts may cause the capsule of the ovary to become damaged or scarred,
such that follicles cannot mature properly and ovulation does not occur.
Infection may also have this impact.
(3) Premature Menopause
This presents a rare and as of yet unexplainable cause of
anovulation. Some women cease menstruation and begin menopause before
normal age. It is hypothesized that their natural supply of eggs has been
depleted or that the majority of cases occur in extremely athletic women
with a long history of low body weight and extensive exercise. There is
also a genetic possibility for this condition.
(4) Follicle Problems
Although currently unexplained, "unruptured follicle
syndrome" occurs in women who produce a normal follicle, with an egg inside of
it, every month yet the follicle fails to rupture. The egg, therefore,
remains inside the ovary and proper ovulation does not occur.
Causes of Poorly Functioning Fallopian Tubes
Tubal disease affects approximately 25% of infertile
couples and varies widely, ranging from mild adhesions to complete tubal
blockage. Treatment for tubal disease is most commonly surgery and, owing
to the advances in microsurgery and lasers, success rates (defined as the number
of women who become pregnant within one year of surgery) are as high as 30%
overall, with certain procedures having success rates up to 65%. The main
causes of tubal damage include:
Caused by both bacteria and viruses and usually
transmitted sexually, these infections commonly cause inflammation resulting in
scarring and damage. A specific example is Hydrosalpnix, a condition in
which the fallopian tube is occluded at both ends and fluid collects in the
(2) Abdominal Diseases
The most common of these are appendicitis and
colitis, causing inflammation of the abdominal cavity which can affect the
fallopian tubes and lead to scarring and blockage.
(3) Previous Surgeries
This is an important cause of tubal disease and
damage. Pelvic or abdominal surgery can result in adhesions that alter the
tubes in such a way that eggs cannot travel through them.
(4) Ectopic Pregnancy
This is a pregnancy that occurs in the tube itself
and, even if carefully and successfully overcome, may cause tubal damage and is
a potentially life-threatening condition.
(5) Congenital Defects
In rare cases, women may be born with tubal
abnormalities, usually associated with uterus irregularities.
Approximately 10% of infertile couples are affected
by endometriosis. . This condition is characterized by excessive growth of
the lining of the uterus, called the endometrium. Growth occurs not only
in the uterus but also elsewhere in the abdomen, such as in the fallopian tubes,
ovaries and the pelvic peritoneum. . The symptoms often associated with
endometriosis include heavy, painful and long menstrual periods, urinary
urgency, rectal bleeding and premenstrual spotting.
(1) Other variables that may cause infertility in women:
At least 10% of all cases of female infertility are caused by an abnormal
uterus. Conditions such as fibroid, polyps, and adenomyosis may lead to
obstruction of the uterus and Fallopian tubes.
- Congenital abnormalities, such as septate
uterus, may lead to recurrent miscarriages or the inability to conceive.
Approximately 3% of couples face infertility due to problems with the female is
cervical mucus. The mucus needs to be of a certain consistency and available in
adequate amounts for sperm to swim easily within it. The most common reason for
abnormal cervical mucus is a hormone imbalance, namely too little estrogen or
too much progesterone.
(2) Behavioral Factors:
It is well-known that certain personal habits and
lifestyle factors impact health; many of these same factors may limit a couple's
ability to conceive. Fortunately, however, many of these variables can be
regulated to increase not only the chances of conceiving but also one's overall
Diet and Exercise
Optimal reproductive functioning requires both proper diet and appropriate
levels of exercise. Women who are significantly overweight or underweight may
have difficulty becoming pregnant.
Cigarette smoking has been shown to lower sperm counts in men and increases the
risk of miscarriage, premature birth, and low-birth-weight babies for women.
Smoking by either partner reduces the chance of conceiving with each cycle,
either naturally or by IVF, by one-third.
Alcohol intake greatly increases the risk of birth defects for women and, if in
high enough levels in the mother ís blood, may cause Fetal Alcohol Syndrome.
Alcohol also affects sperm counts in men.
Drugs, such as marijuana and anabolic steroids, may impact sperm counts in men.
Cocaine use in pregnant women may cause severe retardations and kidney problems
in the baby and is perhaps the worst possible drug to abuse while pregnant..
(3) Environmental and Occupational Factors:
The ability to conceive may be affected by exposure to
various toxins or chemicals in the workplace or the surrounding environment.
Substances that can cause mutations, birth defects, abortions, infertility or
sterility are called reproductive toxins. .
Exposure to lead sources has been proven to negatively impact fertility in
humans. Lead can produce teratospermias (abnormal sperm) and is thought to be
an abortifacient, or substance that causes artificial abortion.
Medical Treatments and Materials
Repeated exposure to radiation, ranging from simple x-rays to chemotherapy, has
been shown to alter sperm production, as well as contribute to a wide array of
A chemical used both in the sterilization of surgical instruments and in the
manufacturing of certain pesticides, ethylene oxide may cause birth defects in
early pregnancy and has the potential to provoke early miscarriage.
Handling the chemicals found in pesticides, such as DBCP, can cause ovarian
problems, leading to a variety of health conditions, like early menopause, that
may directly impact fertility.
A few causes of impotence may be iatrogenic (medically caused).