Consistent age-dependent declines in human semen quality: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of observational studies
PubMed 25462195 · doi:10.1016/j.arr.2014.10.007
What was done
Systematic review and meta-analysis of 90 studies encompassing 93,839 subjects to quantify the impact of male age on seven ejaculate parameters: semen volume, sperm concentration, total sperm count, morphology, total motility, progressive motility, and DNA fragmentation.
What was found
Statistically significant age-associated declines were identified for semen volume, percentage motility, progressive motility, normal morphology, and unfragmented cells. These effects were reported to remain robust against confounding factors. Sperm concentration did not decline with increasing male age, although it declined over calendar time. No numerical effect sizes, confidence intervals, or p-values were reported in the abstract.
Why it matters
The findings demonstrate that paternal biological aging systematically reduces several standard semen quality parameters and sperm DNA integrity. This highlights male age as an important factor in couple subfertility and potential offspring health risks.
Limits
The abstract reports no numerical effect sizes or heterogeneity metrics. The underlying evidence consists of observational studies with potential variation in participant health, fertility status, and semen collection protocols. Clinical pregnancy outcomes and live birth rates were not assessed in the abstract.
Cited by
- supports Male sperm counts change and decline with increasing age.