The association between sperm head elongation and semen quality

Previous studies suggested that sperm head shape may serve as an effective indicator of semen quality. However, there lacks research with large sample and quantitative measurement.

The objective of this retrospective study was to explore the association between sperm head elongation (Width/Length ratio) and routine semen parameters.

From January 2012 to December 2017, 63 866 semen samples were collected from male subjects at 18-60 years of age. Sperm head elongation and routine semen parameters (semen volume, sperm concentration, motility, etc.) were examined with computer-assisted semen analysis (CASA) systems in order to evaluate the association between elongation and semen quality.

Logistic and linear regression models showed that the value of elongation is negatively correlated with sperm concentration, total sperm count, progressive motility, total motility, percentage of morphologically normal spermatozoa, and acrosin activity (all p < 0.001).

The results suggested that higher value of elongation is generally associated with higher risks of abnormality in semen quality. The importance of elongation may be explained by abnormal acrosin activity in the round-headed spermatozoa, which has been reported to cause failure of natural pregnancy.

This study provides a new insight into the sperm head shape, which may be used as a complementary parameter in clinical semen examination and academic research.