[Semen quality of normal fertile men]

To study the semen quality of confirmed fertile men with the time to pregnancy (TTP) of 12 months or less, and analyze the correlation of semen parameters with TTP.

We recruited 1 152 men aged 18 -50 years and with TTP of 12 months. We used questionnaire investigation, physical examination and semen analysis, calculated the normal reference ranges of semen parameters, and analyzed the effects of TTP and other biological characteristics on semen quality.

Seminal examinations showed that the semen volume was 1.5 ml, sperm concentration 17 million per ml, total sperm number 39 million per ejaculate, total sperm motility 41%, progressive sperm motility 33%, normal sperm morphology 5.0%, sperm vitality 53%, and total number of progressively motile sperm 17 million per ejaculate in the 1 152 subjects. In comparison, the total number of progressively motile sperm was significantly smaller in those aged > or = 35 years (P < 0.01), morphologically normal sperm were markedly less in those with BMI > 25.0 (P < 0.01), and sperm concentration, total number of sperm, morphologically normal sperm rate and total number of progressively motile sperm were remarkably lower in those with BMI < 18. 5 (P < 0.05). Cigarette smoking significantly reduced the sperm volume (P < 0.01), and drinking (> 10 g per week) decreased the sperm volume and the total numbers of sperm, morphologically normal sperm and progressively motile perm (P < 0.05). TTP was negatively correlated with sperm concentration, total number of sperm and total number of progressively motile sperm (P < 0.01). The subjects with sexual abstinence of 5 -7 days showed markedly higher sperm concentration, total number of sperm and total number of progressively motile sperm than others (P < 0.01).

In normal fertile men, the fifth centile of semen parameters is close to the WHO normal reference range, TTP is negatively correlated with semen quality, and age, BMI and lifestyle may affect some of the semen parameters.