Evidence for decreasing quality of semen during past 50 years

Abstract

Objective-To investigate whether semen quality has changed during the past 50 years.Design-Review of publications on semen quality in men without a history of infertility selected by means of Cumulated Index Medicus and Current List (1930-1965) and MEDLINE Silver Platter database (1966( -August 1991.Subjects-14947 men included in a total of 61 papers published between 1938 and 1991.Main outcome measures-Mean sperm density and mean seminal volume.Results-Linear regression of data weighted by number of men in each study showed a significant decrease in mean sperm count from 113 x 106/ml in 1940 to 66x 106/ml in 1990 (p<0-0001) and in seminal volume from 3*40 ml to 2-75 ml (p=0.027), indicating an even more pronounced decrease in sperm production than expressed by the decline in sperm density.Conclusions-There has been a genuine decline in semen quality over the past 50 years. As male fertility is to some extent correlated with sperm count the results may reflect an overall reduction in male fertility. The biological significance ofthese changes is emphasised by a concomitant increase in the incidence of genitourinary abnormalities such as testicular cancer and possibly also cryptorchidism and hypospadias, suggesting a growing impact of factors with serious effects on male gonadal function.

Toxicology of Male Reproduction in Animals and Humans

“…Quality of semen, in terms of amount of spermatozoa, has gradually decreased in the last 6 decades [60], determining some adjustments of values considered as normal sperm parameters. While in the 1940s, a man having 100 x lo6 spermatozodml was considered normal [21], in the 1950s and 1960s that amount was reduced to 60 x lo6 cells/mL [I IS]. At present, according to criteria of the World Health Organization (WHO), a man must have only 20 x lo6 sperm cells/mL to be considered potentially fertile [151].…”

Estrogenic and anti-androgenic endocrine disrupting chemicals and their impact on the male reproductive system

“…Environmental substances are considered accountable for the increasing incidence of human reproductive diseases and the consequent decline in reproductive function worldwide (Balabanic et al, 2011;Woodruff, 2011;Marques-Pinto and Carvalho, 2013). It has been demonstrated that over 50 years, the global average sperm count dropped by half, from 113 to 66 million/ml (about 1% at year), whereas sperm morphology/motility abnormalities significantly increased (Carlsen et al, 1992;Marques-Pinto and Carvalho, 2013). The reproductive male function in humans is regulated by a number of hormones and paracrine factors (Svechnikov et al, 2014).…”

Semen quality and reproductive hormones in Faroese men: a cross-sectional population-based study of 481 men

“…In 1992, Carlsen et al 1 published a combined analysis of results from 61 papers published between 1939 and 1991 and showed a significant decline in sperm counts over a 50-year period. A detailed reanalysis of the results found that the conclusion was supported by the underlying studies 2…”