High percentage of abnormal semen parameters in a prevasectomy population.

Objective: To evaluate semen characteristics, testicular volume, and hormonal levels of normal fertile men requiring vasectomy for sterilization.

Design: Retrospective study.

Setting(s): Academic medical centers.

Semen analysis in fertile patients undergoing vasectomy: reference values and variations according to age, length of sexual abstinence, seasonality, smoking habits and caffeine intake.

Context And Objective: Recent studies have shown regional and population differences in semen characteristics. The objective was to establish reference values for semen analysis and to verify the effect that age, length of sexual abstinence, seasonality, smoking habits and coffee consumption have on fertile individuals' semen characteristics.

Design And Setting: Prospective study in the Urology Division, Hospital das Clínicas, Universidade de São Paulo.

Measuring male infertility: epidemiological aspects.

Evidence suggests that human semen quality may have been deteriorating in recent years. Most of the evidence is retrospective, based on analysis of data sets collected for other purposes. Measures of male infertility are needed if we want to monitor the biological capacity for males to reproduce over time or between different populations.