Infertility is defined as the inability of a couple to successfully conceive despite regular unprotected sex for 3 years. This may be due to a problem with either the mother or father, and is fairly common with 1 in 7 couples being diagnosed as sub-fertile (difficulty conceiving) – 84% of couples conceive within the first year of trying, 92% of couples conceive within two years, and 94% of couples conceive within three years. There are several causes of infertility from both parents:-

Male causes

Male infertilityFor a male to be fertile he must produce a high enough number of fully-functioning sperm which are capable of swimming to the fallopian tube and penetrating the oocyte. An infertile male may suffer from obstructive azoospermia (an absence of sperm due to an obstruction along the reproductive tubes), non-obstructive azoospermia (an absence of sperm due to hormone production issues), or oligospermia (a reduced concentration of sperm). Below is a list of causes of male subfertility:
  • Infection
  • Truma
  • Drugs
  • Radiotherapy
  • Varicocele (an abnormal enlargement of the scrotal pampiniform venous plexus)
  • Volume of seminal fluid below 1.5ml
  • Motility of sperm below 40%
  • Correct morphology of sperm below 4%
  • Congenital defect



Female causes

For a female to be fertile she must produce and release an acceptable oocyte and have a fully-functioning uterus and fallopian tubes. An infertile female may suffer from anovulation (the failure to release an oocyte), tubal damage (in which the fallopian tubes are too damaged to carry the oocyte along its length), or there may be an unknown subtle factor affecting her fertility.
Causes of anovulation:

  • Polycyctsic Ovarian Syndrome (PCOS – endocrine syndrome which causes anovulation)
  • Hyperthyroidism (decreased TSH, increased T3/T4)
  • Hypothyroidism (increased TSH, decreased T3/T4)
  • Pituitary dysfunction
  • Hyperprolactinaemia (excess production of prolactin)
  • Hypergonadotrophic hypogonadism (“ovarian failure” – gonads fail to respond to FSH and LH)
  • Hypogonadotrophic hypogonadism (reduced production of FSH and LH)
  • Anorexia
Polycyctic Ovarian Syndrome (PCOS)

Risk factors

There are several risk factors associated with infertility which are listed below:

  • Age – at around the age of 30 the fertility of a female naturally begins to decrease gradually, possibly due to chromosomal abnormalities which occur in the follicles as they age - the same occurs with the sperm of males at around the age of 40
  • Smoking – tobacco smoking affects both parents, with the harmful carcinogens potentially causing damage to the follicles in a female and lowering sperm count and motility in males
  • Alcohol – moderate alcohol use can decrease female fertility
  • Obesity – being overweight lowers female fertility and lowers male sperm count
  • Underweight – restrictive diets and eating disorders can lower the fertility of females
  • Over-exercising – exercising more than 7 hours a week can cause anovulation (athletes do not menstruate regularly)


If a couple has been unsuccessful in conceiving after 3 years of regular unprotected sex then a different approach is needed. As the infertility could arise from either parent it is important to explore which parent, if not both, suffers from infertility and determine the root cause of their problem. Treatment options include intra-uterine insemination (in which seminal fluid containing sperm is delivered to the cervix during the ovulatory phase), the use of donor sperm for a male that suffers from azoospermia, and in-vitro fertilisation (IVF) (in which multiple oocytes are stimulated to developed and are then extracted, fertilised with sperm, and re-implanted into the uterus). The most common treatment (40%) is an intra-cytoplasmic sperm injection in which an oocyte is taken from the mother, a healthy sperm is taken from the father, and then the sperm is directly injected into the oocyte by a clinician using a microscope. The outcome of this treatment, as well as other options, depends on: age of parents, number of previous births, and the duration of infertility.

The process of in-vitro fertilisation (IVF)