A new study suggests that human sperm quality follows a seasonal pattern, peaking in the summer and dipping in the winter.
The research, published Feb. 21 in the journal Reproductive Biology and Endocrinology, analyzed semen samples from more than 15,000 sperm donors in Denmark and the U.S., specifically the state of Florida. Across both populations, the scientists found a consistent pattern: the highest levels of progressively motile sperm — sperm that can swim efficiently in a straight line — appeared in June and July, while the lowest levels occurred in December and January.
