Conception
New life begins when an egg from a woman is fertilised by sperm from a man. Around 20 million sperm per millilitre (ml) need to be present in the ejaculate, with enough mobility and strength to swim the journey to the fallopian tube where conception takes place.
The chance of a young fertile couple conceiving is approximately one in 5 every month. A couple isn’t suspected of having fertility problems until they have tried unsuccessfully to conceive for one year.
Causes of male infertility
The major causes of male infertility are:
- obstructions to the passage of sperm
- problems with sperm (such as low sperm count)
- functional problems (such as impotence)
- hormonal problems.
Obstructions causing infertility in men
Sperm are made in the testicles, then they spend 2 to 10 days passing through a series of small tubes called the epididymis where they mature and exit into a larger tube called the vas deferens. The vas deferens empties the sperm into the ejaculatory duct, where they are mixed with seminal fluid from the seminal vesicles and the prostate gland.
During ejaculation, muscular contractions force the semen into the urethra and out of the penis. Blockages or absences of tubes (including the vas deferens) are the cause of around one in 3 cases of male infertility. Blockages or absences of tubes may be due to vasectomy or injury.
Problems with sperm causing infertility in men
Problems with sperm numbers or quality are thought to be caused by genetic factors. Tiny fragments of the male chromosome may be missing in some men with sperm problems. This may cause:
- Absent sperm (azoospermia) – the semen doesn’t contain any sperm. This may be caused by a blockage of the tubes or the testicles not producing sperm.
- Low sperm count (oligospermia) – the ejaculate has insufficient sperm to bring about conception.
- Abnormal shape – a healthy sperm is shaped like a streamlined tadpole. Abnormally shaped sperm may have problems penetrating the surface of the woman’s egg.
- Poor motility – a healthy sperm has a lashing tail which helps it to swim through the woman’s reproductive system. Sperm with poor motility may swim feebly or not at all.
Functional problems causing infertility in men
Functional problems that can cause or contribute to male infertility include:
- Impotence – the inability to get or maintain an erection sufficient for sexual intercourse.
- Ejaculation problems – retrograde (when semen enters the bladder instead of emerging through the penis) and premature ejaculation.
- Problems with the testicles – caused by injury, infection or chemotherapy.
- Prostatectomy – side effects of the surgical removal of the prostate gland, including infertility, impotence and incontinence.
- Certain disorders – multiple sclerosis, diabetes and other disorders can cause erection and ejaculation difficulties.
- Antibodies – the man’s immune system makes antibodies that hinder the activity of sperm, such as reducing the sperm’s ability to latch onto his partner’s egg.
Hormonal problems causing infertility in men
The levels of male sex hormones are regulated by a series of glands and their hormones. The pituitary gland in the brain influences hormone production in the testicles under the guidance of the hypothalamus. A relatively uncommon cause of male infertility is the failure to make enough of the hormone gonadotrophin.
Diagnosis of male infertility
Investigating suspected infertility requires tests for both the man and his partner. Diagnosing male infertility may involve:
- Physical examination – including medical history.
- Semen analysis – a sample of the man’s semen is investigated in the laboratory and checked for abnormalities and the presence of antibodies.
- Blood tests – to assess hormone levels.
- Testicular biopsy – a fine needle and microscope are used to check the network of tubes within the testicles to see if they contain any sperm.
- Ultrasound scans – to take pictures of the reproductive organs, such as the prostate gland.
Prevention of male infertility
To help improve your fertility, avoid:
- cigarette smoking
- alcohol
- recreational drugs
- sexually transmissible infections
- heat stress from tight-fitting underwear
- anabolic steroids (taken for body-building or sporting purposes).
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