OBJECTIVE

To determine whether age thresholds for elements of semen quality exist.

DESIGN

Retrospective analysis (covariance and point-change analysis) of results of 4,822 semen analyses and 259 fluorescence in situ hybridization (FISH) analyses.

SETTING

Reference laboratory within an infertility clinic.

PATIENT(S): A total of 5,081 men aged 16.5-72.3 years.

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): Ejaculate volume, sperm concentration, sperm motility, sperm motion parameters, strict morphology, and results of FISH analysis.

RESULT(S): Measured parameters of ejaculates did not change before 34 years of age. Immediately thereafter, total sperm numbers (and total motile) declined. Sperm concentration and the proportion of sperm of normal morphology declined after 40 years. Sperm motility and progressive parameters of motile sperm fell after 43 years and ejaculate volume after 45 years. The ratio of Y:X-bearing sperm in ejaculates decreased only after 55 years.

CONCLUSION(S): Our findings project a declining likelihood of pregnancy following intercourse with men >34 years old, independent from the woman's age and increasing with advancing age. Age-related mechanisms associated with this oligoasthenoteratozoospermic progression are discussed.