A study done in France shows that like women, men too have periodical fertility difference and once men cross the age of 35, their fertility starts decreasing. According to the research, the quality of sperm starts deteriorating in the mid-thirties and at the time of 45 years a man’s chances of conceiving differs as one of the three pregnancies ends in miscarriage.

  

The study done on over 12000 couples who had undergone some sort of fertility treatment shows that the men's sperm and its quantity, its ability to move and swim and size and shape etc determine the chances of pregnancy. The study shows that the fact that women who have significantly higher chance of miscarriage and lower rate of pregnancy after 35 years of age applies to men too.