Work

Semen quality of 1559 young men from four cities in Japan: a cross-sectional population-based study

Year: 2013

Type: article

Abstract: OBJECTIVES: To provide information of semen quality among normal young Japanese men and indicate the frequency of reduced semen quality. DESIGN: Cross-sectional, coordinated studies of Japanese young men included from university areas. The men had to be 18-24 years, and both the man and his mother had to be born in Japan. Background information was obtained from questionnaires. Standardised and quality-controlled semen analyses were performed, reproductive hormones analysed centrally and results adjusted for confounding factors. SETTING: Four study centres in Japan (Kawasaki, Osaka, Kanazawa and Nagasaki). PARTICIPANTS: 1559 men, median age 21.1 years, included during 1999-2003. OUTCOME MEASURES: Semen volume, sperm concentration, total sperm count, sperm motility, sperm morphology and reproductive hormone levels. RESULTS: Median sperm concentration was 59 (95% CI 52 to 68) million/ml, and 9% and 31.9% had less than 15 and 40 million/ml, respectively. Median percentage of morphologically normal spermatozoa was 9.6 (8.8 to 10.3)%. Small, but statistically significant, differences were detected for both semen and reproductive hormone variables between men from the four cities. Overall, the semen values were lower than those of a reference population of 792 fertile Japanese men. CONCLUSIONS: Assuming that the investigated men were representative for young Japanese men, a significant proportion of the population had suboptimal semen quality with reduced fertility potential, and as a group they had lower semen quality than fertile men. However, the definitive role-if any-of low semen quality for subfertility and low fertility rates remain to be investigated.

Source: BMJ Open

DOI: 10.1136/bmjopen-2012-002222