When I did my first IVF in 1989, we hardly saw any male infertility. At a guess, no more than 15-20% of infertilty was related to problems with the sperm. Over the years we have seen a dramatic increase , and these days half or more are due to poor sperm quality.
There is no agreement as to why this is so but the general consensus is that something in the environment has affected the proper development of the cells in the testicles that produce sperm so either there are too few sperm or the sperm are of poor quality when produced.
Worse still, it may be that this effect is taking place while the little baby is still in the mother’s womb.
We are still struggling to find the cause and there is intense research into which of the thousands of chemicals in the environment is to blame. Couples suffering from male infertility are also frustrated because many of the available medical treatments seem not to be able to correct the sperm defects.
While ICSI allows some couples to have children, not everyone can afford this treatment.
In the meantime, men trying to have children should be aware of what they eat and drink, and make the appropriate changes to their lifestyle including eating healthily, excercising, reducing stress, smoking & alcohol etc.