Seasonality likely to affect male fertility, study shows

The quality of sperm is highest in the summer and lowest in the winter, according to a new study by scientists at University of Manchester, Queen's University (Ontario, Canada), and Cryos International (Aarhus, Denmark). The researchers found the same pattern of seasonal variation in the highest quality sperm in two very different climates—Denmark and Florida—suggesting that seasonality affects male fertility more than temperature alone.