Something strange is happening to millions of men in certain countries around the world. According to a comprehensive assessment of nearly 200 studies conducted between 1973 and 2011, the sperm count among men in the United States, Europe, Australia, and New Zealand has been rapidly and startlingly declining. Study co-leader Hagai Levine, an epidemiologist at the Hebrew University of Jerusalem, said that during that time, the average sperm concentration of men in those countries dropped by 52.4 percent, and sperm count fell by 59.3 percent. The trend is continuing, Levine said, and prompts concerns about both male fertility and health. "This study is an urgent wake-up call for researchers and health authorities around the world to investigate the causes of the sharp ongoing drop in sperm count," Levine told Scientific American. While this assessment did not look into possible reasons for the decline, previous studies have pointed to a number of factors, including obesity, smoking, stress, and chemicals and pesticides that men in those areas could be exposed to. Interestingly, sperm counts in Asia, Africa, and South America seem to have stayed relatively constant, although fewer studies have been conducted in those regions.
Some facts about sperm:
- A single sperm can live for up to five days inside the female reproductive tract.
- Despite some longstanding beliefs, a man's choice of underwear has little to no effect on his sperm count.
- Sperm counts vary widely, but "normal" is considered somewhere between 15 million and 200 million sperm per milliliter of semen.