Researchers from University Hospital Zurich analyzed semen samples from 7,068 men, ages 25 to 40, undergoing fertility treatment. Lead study author Dr. Brigitte Leeners says, "Male semen quality varies with both circadian and circannual rhythms. Collection of semen in the early morning, where semen quality was highest, can be used to improve natural fertility."
The data revealed semen collected in March, April and May had the greatest concentration of sperm; and samples collected before 7:30 a.m. showed the highest levels of concentration as well. The take-home message: get busy on early Spring mornings to boost your chances of making a baby.