title: Evaluation of semen parameters in semen donors in a ten-year period in the city of São Paulo.
abstract: OBJECTIVE
  To evaluate sperm concentration, morphology and motility of Brazilian semen donors from 1992 to 2003, in the city of São Paulo.
  
  
  METHODS
  Retrospective study analyzing 182 donor semen samples from 1992 to 2003. The first and the second donated sample were analyzed for each donor. Donor average age was 30.8 years. Means with standard errors, medians with minimum and maximum values, and interquartile ranges were calculated for age, sperm concentration, semen volume, oval morphology and motility. The relation between each characteristic of the semen samples and the year of donation, as well as donor age and season of the year were studied by linear and multiple regression analysis.
  
  
  RESULTS
  Linear regression analysis showed that the sperm concentration (R2 = 19.1%, R2 = 20.2%, p < 0.0001 respectively) and the oval morphology (R2 = 13%; R2 = 13.5%; p < 0.0001, respectively) decreased significantly, even when the first or the second sperm collection is considered. The ejaculated volume showed slight increase during the period for both samples (R2 = 2.2%, p = 0.048; R-sq = 2.4%. p = 0.038, respectively). All characteristics did not depend on the donors' age or season of the year when the samples were obtained.
  
  
  CONCLUSIONS
  There was a decrease in spermatic concentration and percentage of oval sperm of semen donors samples from 1992 to 2003, in the city of São Paulo.
authors.affiliation: Hospital Israelita Albert Einstein, São Paulo, SP, BR.
authors.forename: Sidney
authors.initials: S
authors.lastname: Glina
authors.affiliation: Projeto ALFA, São Paulo, SP, BR.
authors.forename: Thiago
authors.initials: T
authors.lastname: Nova
authors.affiliation: Sperm Bank and Human Reproduction Unit, Hospital Israelita Albert Einstein - HIAE, São Paulo, SP, BR.
authors.forename: Vera Beatriz Fehér
authors.initials: VB
authors.lastname: Brand
authors.affiliation: Sperm Bank and Human Reproduction Unit, Hospital Israelita Albert Einstein - HIAE, São Paulo, SP, BR.
authors.forename: Erica
authors.initials: E
authors.lastname: Molina
authors.affiliation: Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS, BR.
authors.forename: Andrea Giannotti
authors.initials: AG
authors.lastname: Galuppo
authors.affiliation: Sperm Bank and Human Reproduction Unit, Hospital Israelita Albert Einstein - HIAE, São Paulo, SP, BR.
authors.forename: Nadeje Regina
authors.initials: NR
authors.lastname: Correa
authors.affiliation: Clinical Research Center, São Paulo, SP, BR.
authors.forename: Frederico Rafael
authors.initials: FR
authors.lastname: Moreira