Introduction

For pregnancy to occur there must be a fertile sperm and an egg, a mean of bringing them together and a receptive endometrium to allow the resulting embryo to implant. A defect at any of these stages can lead to subfertility. It has been estimated that in 35 per cent of cases a male factor is the reason for infertility. In the remaining 65 per cent of cases, a female factor is identified in 50 per cent of couples and no cause will be identified in the remainder.

Causes That May Affect The Infertility

1. Ovulation disorders

   Infertility is most commonly caused by problems with ovulation (the monthly release of an egg) and account for 30% of women’s infertility. Ovulation problems can occur as result of a number of conditions

   • Polycystic ovarian syndrome (PCOS), a condition that makes it more difficult for the ovaries to produce an egg.
   • Malfunction of the hypothalamus which 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.
   • Malfunction of the pituitary gland, which is responsible to produce and secrete 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, tumour or if there is a chemical imbalance in the pituitary.
   • Thyroid problems, both an overactive thyroid gland (Hyperthyroidism) and an underactive thyroid gland (hypothyroidism) can prevent ovulation.
   • Premature ovarian failure, where a women’s ovaries stop working before she is 40.
   • Scarred ovaries due to physical damage to the ovaries may result in failed ovulation. For example, multiple injuries for repeated ovarian cysts may cause the capsule of the ovary to become damaged or scarred, such that follicles cannot mature.
   • Follicle Problems, “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.
      
2. Poorly Functioning Fallopian Tubes

   Tubal disease affects approximately 25% of infertile couples. The main causes of tubal damage include:

   • Infection
     Could be due to bacteria or viruses and usually transmitted sexually, these infections commonly cause inflammation resulting in scarring and damage. A specific example is Hydrosalphinx, a condition in which the fallopian tube is occluded at both ends and fluid collects in the tube.
      
   • 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.

   • 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

   • Ectopic Pregnancy

   This is a pregnancy that occurs in the tube itself and may cause tubal damage.

   • Congenital Defects

   In rare cases, women may be born with tubal abnormalities, usually associated with uterus irregularities

3. Endometriosis

   Approximately 10% of infertile couples are affected by endometriosis. The condition is characterized by excessive growth of the lining of the uterus, called the endometrium outside the uterine cavity. Growth occurs not only in the uterus but also elsewhere in the abdomen, such as in the fallopian tubes, ovaries and the pelvic peritoneum. Endometriosis can cause damage to the fallopian tubes or tubal blockage and also failure of ovulation.
    

4. Additional factors
   1. Other variables that cause infertility in women

      • Submucosal fibroids develop in the muscle beneath the inner lining of the uterus, may prevent an embryo from implanting into the uterus.
      • Congenital uterine abnormalities, such as septate uterus, may lead to recurrent miscarriages or the inability to conceive.
      • Problems with the females cervical mucous. The mucous need 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.

      • Diet and Exercise
        Optimal reproductive functioning requires both proper diet and appropriate levels of exercise. Women who are significantly overweight may have difficulty becoming pregnant.
         
      • Smoking
        Smoking in pregnancy increases the risk of miscarriages, premature birth, and low- birth-weight babies in women. Smoking by either partner reduces the chance of conceiving with each cycle, either naturally or by IVF.
         
      • Alcohol
        Alcohol intake greatly increases the risk of birth defects for women and, if in high enough levels in the mother’s blood, may cause Fetal Alcohol Syndrome.
         
      • Medication
        The side effects of some types of medication and drugs can affect fertility. Non-steroidal anti-inflammatory drugs (NSAIDS), long term use, or a high dosage, such as ibuprofen or aspirin, can make it more difficult to conceive. NSAID use is associated with luteinized unruptured follicles. Chemotherapy which is medicines used for a treatment for cancer can sometimes cause ovarian failure. Ovarian failure can be permanent. Neuroleptic medicines are antipsychotic medicines often used to treat psychosis. They can cause missed periods or infertility. Cocaine use in pregnant women may cause severe retardations and kidney problems in the baby.
         
   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.

      • Lead
        Exposure to lead sources has been proven to negatively impact fertility in humans. Lead can produce teratospermias (abnormal sperm), and can cause 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 ovarian problems.
         
      • Ethylene Oxide
        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 potential to provoke early miscarriage.
         
      • Dibromochloropropane (DBCP)
        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.