Is the quality of donated semen deteriorating? Findings from a 15 year longitudinal analysis of weekly sperm samples.

BACKGROUND

Studies suggest that global semen quality is declining, but the debate remains open owing to geographic variation.

OBJECTIVES

To evaluate temporal trends of sperm parameters - namely concentration, motility and total motile sperm count - in sperm donated during the period 1995-2009.

METHODS

In a retrospective longitudinal cohort study we analyzed the sperm count and motility of 2182 semen samples provided on a weekly basis by 58 young, healthy, fertile, university-educated, paid donors.

RESULTS

Despite the lowering of criteria for sperm parameters satisfactory for donation that were implemented in 2004, 38% of applicants for sperm donation are now rejected based on semen quality as compared to a third of applicants 10-15 years ago (P < 0.001). If the old strict criteria were in place 88% of candidates would be rejected today (P < 0.0001). Over the study period, the average sperm parameters dropped from a concentration of 106 +/- 25 million spermatozoa/ml with 79% +/- 4.3% motility to 68 +/- 14 million/ ml with 66% +/- 4.5% motile sperm (P < 0.0001, P < 0.0001, respectively). The total motile sperm count per ejaculate also decreased, from 66.4 +/- 18.2 million to 48.7 +/- 12 million (P < 0.005). When the previous criteria were implemented for the analysis of the latest group of sperm donors, only 18% of donors had an acceptable sperm quality, with an average concentration of 87 +/- 12 million spermatozoa/ml, 73% +/- 2.6% motile sperm and total motile sperm count of 53.1 +/- 3.8 million per ejaculate - still significantly lower than 15 years ago (P= 0.01, P= 0.003, P= 0.058 respectively).

CONCLUSIONS

The rapid deterioration of sperm quality among fertile semen donors is alarming and may lead to cessation of sperm donation programs.