“For decades, researchers have been asking if sperm counts are decreasing worldwide, and if so, whether this presages a global decline in male fertility. Most recently, a large systematic review and meta-regression analysis sought to identify trends in sperm counts between 1981 and 2013 and found that sperm counts appeared to be declining rather than stabilizing. One of the complicating features of relying on sperm count as a marker of fertility is that a low sperm count does not guarantee an inability to conceive. A large variety of factors, including tobacco, alcohol, and drug use; psychological stress; obesity; insufficient sleep; and environmental factors such as air pollutants and heavy metals, have been identified as potential risk factors affecting semen quality. Initial investigations recommended for a patient presenting with fertility concerns include a detailed history, physical examination, investigations based on the clinical context, and semen analysis for most patients. Although the evidence is conflicting, our review suggests that the potential decline in male sperm counts does not necessarily translate to a decline in male fertility.”
Global decline of male fertility: Fact or fiction? via BCMJ.