Decline in semen quality in men in Northern Taiwan between 2001 and 2010

Semen quality is a key indicator of the male reproductive ability. The decline in semen quality has been debated for several decades. However, data on decline in semen quality might be inconsistent given factors such as geographical area, ethnicity, environmental exposure and lifestyle changes. This study aimed to provide information on the semen quality of men in Northern Taiwanese. We recruited 7,187 male participants between 2001 and 2010 from a reproductive medical center. The age of the participants ranged from 26 to 57 years, with a mean age of 36.9 ± 4.77 years. Semen analysis was performed through standardized methods outlined in the World Health Organization laboratory manual. Increasing age (per year) was significantly and negatively associated with semen volume (1.006 ml), progressive sperm motility, rapid progressive sperm motility and sperm with normal morphology (reduction by 1.010%, 1.013% and 1.002% per year, respectively). In addition, sperm concentration, semen volume, number of sperms, progressive sperm motility, rapid progressive sperm motility, and sperm with normal morphology were significantly reduced annually by 1.013 × 10⁶/ml, 1.015 ml, 1.028 × 10⁶, 1.021 %, 1.017% and 1.016%, respectively). Age-period-cohort (APC) analyses revealed that age and cohort had effects on reduction of the progressive and rapid progressive sperm motility. Moreover, all the sperm parameter values were significantly reduced annually. Our findings provide useful information for clinical practice and public health investigations of male reproductive health.