Causes of Human Infertility.

Authoritative medical papers, ranking the causes of human reproductive failure, are very thin on the ground. There is an often quoted paper published in the British Medical Journal of Dec 1985 and attributed to Dr Mike Hull et al. This remains as current today as it did twenty-five years ago when it was first published. Here the authors rank the causes of infertility thus:

Unexplained – 28%
Sperm Defects – 24%
Ovulation Failure – 21%
Tubal Damage – 14%
Endometriosis – 6%
Coital Failure – 6%

It is interesting to note that in spite of our best efforts and sophisticated diagnostic equipment such as MRI and CT scan, that still the largest group of cases of infertility today are unexplained or are of unknown cause. This remains a humbling reminder of just how complex human reproductive physiology actually is and how limited are our influences on this mysterious process.

Something else worth noting also is that the majority of cases of infertility, where a cause can actually be identified, are not female engendered at all but the deficit actually lies on the male side. Sperm defects – low sperm count or oligospermia and poor sperm motility or asthenospermia together account for up to quarter of all cases of infertility. Therefore, surely it only makes sense that in all cases of infertility, investigation should start with a carefully conducted semen analysis since this is the cheapest and least invasive test of all and the one must likely to unearth the underlying cause in any given case of infertility. And yet, one suspects, this may not be a universally accepted principle. Cultural idiosyncrasies can get in the way of common sense.

Coital Failure, as an underlying cause of childlessness, is also interesting. This brings us into an area of medicine in which I have long had a specialist interest – namely that of sexual dysfunction. People tend to look askance at sexuality as if it had nothing to do with things other than pleasure and function and bedroom prowess. We do not often think of sexual dysfunction as an underlying cause of infertility. Yet here we have this study by Hull reminding us that as much as 6% of all infertile couples are that way because of coital (meaning intercourse) failure.

Unfortunately we are given no further breakdown of this figure and are not told which sexual dysfunction, for example, causes the most problems for couples anxious to start a family. As a practitioner in this area I can but throw some anecdotal light on the subject. Childlessness or the fear of never being able to start a pregnancy and pass down ones precious genes is often a stronger motivating factor to go and seek help than is the actual sexual dysfunction itself. Or put another way, sexual dysfunction often first comes to light, not as a complaint in its own right, but as the primary underlying cause of infertility.

Four sexual difficulties can lead to this situation; two for men and two for women. On the men’s side our old friend erectile dysfunction, even that caused by performance anxiety, can be so severe as to make reproduction impossible. The same is true of premature ejaculation. Where this condition is severe enough a man may always be incapable of refraining from ejaculating before intercourse commences.

For women, pain during intercourse or dyspareunia may be so persistent and severe as to make reproductive intercourse impossible. The same is true of Vaginismus. When this is severe enough all attempts at penetrative sex are doomed to failure. It is the resulting failure to start a pregnancy as much or more that anything else that drives people to seek help.

When I return to this subject I want to say something about the folly of a too ridged adherence to a sometimes mythical fertile period and how this in fact can be contra productive. I also need to say something about all of those cures for low sperm counts. Both of these areas make for rich pickings by the sharks that infest the Internet waters where the vulnerable and infertile hang out.

Author's Bio: 

I am an Irish medical doctor working in Kildare outside Dublin. I specialise in Online Consultation for men and women who may be suffering from a sexual dysfunction or perceive difficulty. Nowhere are people more vulnerable or so easily exploited as when they are suffering from something that’s hard to talk about and they are on the Internet trying to find solutions. I want to help these people in as honest and professional a way as I can.

Please visit me on You may ask me a question from there and it is FREE. I would be delighted to try and help you.