Reference values for human semen characteristics: a multicentre study in China (Preprint)

Abstract

There has been no comprehensive evaluation of semen characteristics in reproductive age group nationwide in China. The applicability of the current standard reference values to Chinese males is limited.

This study was designed as an integrated analysis for multicentre data. We aimed to establish semen reference values for the grneral population and conduct a comprehensive evaluation of them to provide solid evidence for the current national semen status.

This multicentre population-based cohort study enrolled 65,335 semen donors from 16 human sperm banks covering all 7 geographic regions, from April 20, 2013 to August 31, 2019. Healthy young men aged 20 to 45 years were included in this study. Participants were included and semen samples were analyzed according to the standard practices recommended by WHO.

The study revealed significant variations in semen characteristics across different geographic regions, age groups, years, and seasons in China, but no notable declining trend was observed. A stronger decreasing trend with age was observed for the upper distributions of all semen parameters compared with the lower distribution. And age-related trends were divergent in different semen parameters. The variance-weighted estimates and 95% confidence intervals (CI) of 5th centiles were: 1.2478 ml (95% CI: 1.2477, 1.2479) for semen volume, 10.776 × 106/ml (10.749, 10.804) for sperm concentration, 16.513 × 106/ejaculate (16.304, 16.722) for total sperm count, 24.430% (24.369, 24.492) for progressive motility, 25.926% (25.861, 25.990) for total motility, and 5.829 × 106/ejaculate (5.770, 5.887) for motile sperm count.

Lower reference values have been established for sperm concentration, total sperm count, progressive motility, total motility, and total motile sperm count, differing from current standard reference values. These newly developed reference values could serve as a more applicable representation of the general male population in China, benefiting from a large number of subjects that provide robust and geographically representative information.