title: Freezability and semen parameters in candidates of sperm bank donors: 1992-2010.
abstract: There has been considerable concern worldwide about possible semen quality  deterioration over the last 2 decades. The aim of this study was to evaluate  freezability and semen quality of healthy young males during the years  1992-2010. A total of 1211 young (20-32 years old) candidates for  sperm bank donation were recruited into the study with no exclusion criteria.  They were instructed to observe 2 to 3 days of abstinence from sexual  activity, and most of them supplied 2 specimens each. Average values of the  various semen parameters, including freezing survival, were calculated for  each participant. The change in different semen parameters over years,  according to yearly and monthly average temperatures, was evaluated by SAS  PROC SURVEYREG analysis. During that period, there were significant increases  in motility and vitality percentages, as well as in the percentage of thawed  sperm motility. The parameters of volume, concentration, normal morphology,  total count, and total motile count showed a significant decrease with years  (P < .01). The significant increase in average yearly temperature  (P < .004) had limited, nonsignificant association with any of the  semen variables. However, average monthly temperature contributed  significantly to the trend of semen quality parameters (ie, specimen volume,  concentration, percentage of normal morphology, and thawed motility). To the  best of our knowledge, this is the first demonstration of the occurrence of an  improvement in percent thawed motility over the years, and its significance  lies in enabling a higher proportion of sperm bank candidates to be suitable  for donation. It is suggested that the global warming phenomenon might have  only partial contribution to semen variable changes over the years.
authors.affiliation: Institute for the Study of Fertility, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, 6 Weizman St, Tel Aviv 64239, Israel. layogev@zahav.net.il
authors.forename: Leah
authors.initials: L
authors.lastname: Yogev
authors.forename: Gedalia
authors.initials: G
authors.lastname: Paz
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Kleiman
authors.forename: Esther
authors.initials: E
authors.lastname: Shabtai
authors.forename: Ronni
authors.initials: R
authors.lastname: Gamzu
authors.forename: Amnon
authors.initials: A
authors.lastname: Botchan
authors.forename: Ofer
authors.initials: O
authors.lastname: Lehavi
authors.forename: Haim
authors.initials: H
authors.lastname: Yavetz
authors.forename: Ron
authors.initials: R
authors.lastname: Hauser
mesh_terms: D000328:Adult; D048430:Cell Shape; D002470:Cell Survival; D015925:Cryopreservation; D046148:Donor Selection; D057232:Global Warming; D006801:Humans; D007557:Israel; D008297:Male; D012621:Seasons; D012661:Semen; D055101:Semen Analysis; D013074:Sperm Banks; D013076:Sperm Count; D013081:Sperm Motility; D013094:Spermatozoa / Q000473:pathology*; D013997:Time Factors; D014019:Tissue Donors; D055815:Young Adult