The Cause of infertility

The cause of infertility can be related to the male partner, the female partner or sometimes both.

In about 35% of couples, the cause of infertility is related to the male partner.

In about 55% of infertile couples, the cause of infertility is related to the female partner.

In about 10% of infertile couples, the cause remains unidentified.

The Cause of male related infertility

A fertile male should be able to deliver an adequate amount of normal sperm to a female’s vagina, and the sperm should be able to fertilize the egg.

Sub-fertility in men are caused by conditions that result in reduced sperm production or the absence of sperm in semen.

The cause of reduced sperm production

Increased temperature of the testes

This can influence the amount of sperm produced and can also alter the quality of the sperm produced in the testes.

  • Conditions of excessive heat
  • Illness that cause a prolonged period of fever

The effect of increased temperature on the testes can last up to 3 months.

Hormonal disorders

  • Disorders of the adrenal gland, pituitary gland and the hypothalamus (all involved in the production of testosterone)
  • Hypothyroidism
  • Hyperprolactinemia (increased levels of prolactin, a hormone that stimulates the production of milk)
  • Hypogonadism (low levels of testosterone and/or decreased production of sperm). This is often related to obesity.

genetic disorders

  • Cystic fibrosis
  • Klinefelter syndrome (when a male is born with and extra copy of the X-chromosome
  • Disorders that cause abnormality in the sex chromosomes

disorders of the testes

  • Infections or injury to the testes
  • Mumps Orchitis (mumps that affects the testes)
  • Testicular tumours
  • Undescended testes (testes that fails to descend into the scrotum and remains in the abdomen)
  • Varicocele (Varicose veins in the testes)


  • Anabolic steroids
  • Use of alcohol and caffeine in excessive amounts
  • Medication used to treat malaria
  • Aspirin used for a prolonged period of time
  • Monoamine oxidase inhibitors (a type of antidepressant)
  • Antibiotics, such as nitrofurantoin, sulfasalazine and cotrimoxazole
  • Opioids (narcotic drugs)
  • Chemotherapy drugs used to treat cancer, e.g. GnRH agonists and Cyclophosphamide
  • Marijuana
  • Corticosteroids, such as prednisone
  • Use of androgens as well as antiandrogens

Exposure to industrial or environmental toxins

  • Exposure to heavy metals, e.g. lead
  • Pesticides
  • Phthalates (chemicals used in plastic)
  • Polychlorinated biphenyl compounds

Absence of sperm in semen (Azoospermia)

Disruption of the sperm's passage out of the body

  • Missing epididymis (where sperm is stored and matured), usually in the case of males with cystic fibrosis
  • Blockage or absence of vasa deferentia (the tubes that transport sperm from the epididymis to the ejaculatory ducts), also in the case of males with cystic fibrosis
  • Absence of seminal vesicles (which nourishes the sperm)
  • Blockage of the ejaculatory ducts

retrograde ejaculation

When the sperm travels back into the bladder, instead of exiting the penis

  • Diabetes mellitus
  • Nervous system dysfunction
  • Side-effect of pelvic surgery

Erectile dysfunction

When a male is unable to attain or maintain an erection sufficient for sexual intercourse

  • Blood vessel disorders
  • Diabetes mellitus
  • Nervous system disorders (e.g. Alzheimer disease, Parkinson disease, Multiple sclerosis, etc.)
  • Anxiety or depression
  • Use of certain antidepressants, hormonal drugs and drugs used for high blood pressure
  • Narcotics such as cocaine, heroin, etc.
  • Unknown causes

The cause of female related infertility

A woman’s ability to conceive decreases with age. Optimal fertile age in women are considered to be up to the mid-twenties after which it steadily declines. However, it declines at a rapid rate after the age of 35.

Lifestyle factors that also have a negative impact on female fertility are obesity (BMI > 30), being underweight (BMI < 20), smoking, excessive alcohol intake and consuming too much caffeine.

Other causes of infertility as described below are more complex and can be diagnosed with the help of investigations performed by a Fertility Specialist

Blocked or damaged fallopian tubes

  • PID (pelvic inflammatory disease) and STI’s (sexually transmitted diseases) e.g. Chlamydia trachomatis causing excessive inflammation in the pelvis
  • Complications during surgery as in the case of severe appendicitis
  • Endometriosis of the fallopian tubes
  • Ectopic pregnancies that occurs in the fallopian tube
  • Tuberculosis that affects the fallopian tubes
  • Rare infection caused by intrauterine devices

Abnormalities within the pelvis

  • Congenital abnormalities of the uterus, such as uterine septums
  • Polyps of the endometrial lining
  • Adhesions in the uterine cavity
  • Fibroids (benign tumours of the uterus)
  • Endometriosis

ovulation problems

The most common cause of female subfertility

  • Decreased ovarian reserve (decreased amount and quality of eggs available)
  • PCOS (polycystic ovarian syndrome)
  • Primary ovarian insufficiency (also known as premature menopause)

Abnormalities of the cervix

  • Cervical stenosis (narrowing of the cervical canal)
  • Cervical dysplasia (abnormal cells found on the surface of the cervix that develop into cancer with time)
  • Abnormal cervical mucus (the mucus does not become penetrable when ovulation takes place which prevents sperm from entering the uterus, it contains antibodies that destroy the sperm or it allows infection from the cervix to enter the uterus)

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