Within-subject variability of human semen in regard to sperm count, volume, total number of spermatozoa and length of abstinence

in Reproduction

Summary. The within-subject variability of the semen sperm count (n), volume (v) and the total number of spermatozoa (N) was studied on 220 ejaculates from 36 normal subjects after an abstinence of 7 days or less. For each of the three variables, the within-subject standard deviation, σ, was practically proportional to the mean, μ; the common value of the coefficient of variation σ/μ for all subjects was very high: 0·39 for n, 0·28 for v and 0·55 for N. The 95% confidence intervals based on a single ejaculate were asymmetrical and very large, the lower and upper limits being respectively 0·5 × n and 2·3 × n; 0·7 × v and 1·8 × v; 0·4 × N and 2·9 × N. The three semen characteristics for a given subject were highly correlated with the length of abstinence: for an increase in abstinence of 1 day there were mean increments of 13 × 106/ml for n, 0·4 ml for v, and 87 × 106 for N.


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