According to Chinese medicine theory, there are four seasons in heaven, spring, summer, autumn and winter; spring planting, summer growing, autumn harvesting and winter storage; autumn is the time when fruits ripen and a good harvest is obtained, and sperms also grow best in this season, which is the most suitable for conception. A U.S. study found that changes in male semen quality are related to the seasons. The researchers analyzed the semen of men suffering from infertility over 32 months separately. It was found that the percentage of immature sperm, which was higher in summer than in any other season, was due to the heat. Winter, however, predisposed men to sperm tail defects. Spring was the season in which the frequency of sperm tail defects was the highest. Sperm with tail defects are less mobile and have difficulty reaching the egg to fertilize it. In contrast, sperm motility is highest in the fall and semen quality is the best. Overall, winter has the highest sperm count, followed by spring; fall has the highest sperm motility is. And the period of human conception to June to November is appropriate, of which the best time should be the fall of each year. Although human beings do not have as obvious as the animals of the estrous period, but according to relevant information, in the temperature is suitable, the climate of the season, the body of the various physiological activity is committed to be more active, sex hormone secretion increases, libido is also exuberant, the woman is more likely to get pregnant. Therefore, the fall sperm is the most robust, for couples who plan to have children to seize the opportunity.