An eminent veterinary scientist told me this interesting fact the other day.  A chimpanzee produces 2737 million sperms in a day, which is sufficient for four ejeculates.  In comparison, a man on an average produces 176 million sperms per day; this production is just sufficient for one ejaculate.  This means, even as a closely related species human sperm count is lower.

Even epidemiological evidences are now available confirming decreasing quality of human sperms during the last fifty years. (B.M.J.-1992).  Of course, fertility depends on both male and female partners.  Male factor sub fertility plays a role in approximately 50% of sub fertile couples.

Smoking, alcohol use, stress and high temperature are known to reduce sperm production.  Active as well as passive smoking increases blood nicotine, cotinine levels which are toxic to human gametes.  Smoking appears to have an acute toxic effect on process of conception. A permanent and cumulative damaging effect is also suggested.   Occupational exposure to heavy metals like lead, cadmium are known to be spermato toxic.  The relationship between good nutrition and reproduction is well established. Reduced dietary intake of zinc as in starvation, malabsorption syndromes, parasitic diseases, drug abuse, liver and renal diseases results in gonadal hypofunction, reduced sperm count and impotence.

The message is by prevention of sexually transmitted diseases and optimum and timely changes in lifestyle like stopping active as well as passive smoking, increased intake of nutrients like zinc, folate, iodine etc. this global problem can be prevented to a certain extent.