Just read an interesting article at BBC online by Dr Allan Pacey who is a fertility expert at the University of Sheffield in which he gives his personal viewpoint on male fertility issues.
Around one in six couples experience fertility problems at some point in their lives and seek advice from a doctor.Tests show that between 30% to 50% of problems are with the male partner. During any one year, millions of men throughout the world struggle to father children, and many more may not be aware of a fertility problem because they have not yet decided to start a family. Others may realise there is a problem and simply give up trying. Of the many reasons why a man may not be able to father a child the most common is that he simply does not produce enough sperm, or that the sperm he does ejaculate are of poor quality. In some European countries, such as Denmark, it has been estimated that up to 25% of young men have poor semen quality. A worry is whether this proportion has increased in recent years, and whether today’s men are as fertile as their fathers were.
Read the full article here http://news.bbc.co.uk/1/hi/health/8009703.stm