Declining sperm quality in New Zealand over 20 years.

AIM

To investigate whether semen quality has changed in New Zealand over the last 20 years.

METHOD

A retrospective study from 1987 to 2007. The sperm concentration, volume of seminal fluid, and the percentage of motile sperm were analysed from the first semen sample of 975 men presenting as sperm donors in Auckland and Wellington.

RESULTS

Linear regression showed that the mean concentration of sperm decreased from 110 x 10(6) per millilitre in 1987 to 50 x 10(6) per millilitre in 2007 (p<0.001); an average reduction of 2.5% annually. The volume of semen also fell significantly from 3.7 ml to 3.3 ml (p<0.001). There was no concomitant change in the duration of abstinence.

CONCLUSION

The decline in semen volume and sperm concentration in men presenting as sperm donors may indicate a reduction in the semen quality of New Zealand men over the past 20 years.