Semen analyses in 1,283 men from the United States over a 25-year period: no decline in quality

The effects of male aging on semen quality, sperm DNA fragmentation and chromosomal abnormalities in an infertile population

“…A significant age-dependent decrease [2,25] as well as constant values over the age range [19] or even a non significant age dependent increase with age [26] have been detected in healthy men. In infertile patient's sperm concentration remains unalterated [22] or increases [21,23,[26][27][28][29]. In our study we had found that sperm concentration increases with age in infertile men but remains constant in fertile men.…”

Macleod Revisited: Sperm Count Distributions in 374 Fertile Men From 1971 to 1994

“…This group has previously been reported on. 6 Although all of these men presumably had been fertile in the past, only 374 definitively reported on a prevasectomy questionnaire that they had fathered children. These men are the subject of the remainder of this paper.…”

“…[1][2][3][4][5] We have recently published data showing no decline in sperm counts in men who banked sperm prior to vasectomy from 1970 to 1994 from three United States sperm banks at different geographic locations. 6 Since MacLeod and Gold 7 is still cited most prominently in defining a ''normal'' sperm count, we compared our sperm count data from 374 men with proven fertility who banked sperm prior to vasectomy in Minnesota from 1971 to 1994 to MacLeod and Gold's data from 1951 to look at whether sperm count distributions have changed over the last 40 years. We calculated the mean, median, standard deviation, and sperm count distributions exactly as MacLeod and Gold 7 did to compare the two populations.…”

“…In fact we found a statistically significant increase in sperm counts in the United States from 1970 to 1994. 6 To further evaluate whether there has been a change in sperm count distributions over time, we compared sperm count distributions from a group of men with proven fertility from 1971 to 1994 to those from the first study on sperm count distributions published by MacLeod and Gold in 1951. 7 …”

Endocrine disruptors and falling sperm counts: lessons learned or not!

“…43,44 Another important variable that was also not accounted for was the regional differences in sperm counts which were observed in Europe and North America. Fisch and co-workers 45 investigated sperm concentrations from vasectomy clinics in New York, Minnesota and California, and …”