Human semen quality in the new millennium: a prospective cross-sectional population-based study of 4867 men

Niels Jørgensen; Ulla Nordström Joensen; Tina Kold Jensen; Martin Blomberg Jensen; Kristian Almstrup; Inge Ahlmann Olesen; Anders Juul; Anna-Maria Andersson; Elisabeth Carlsen; Jørgen Holm Petersen; Jorma Toppari; Niels E Skakkebæk

doi:10.1136/bmjopen-2012-000990

Male Fertility · Semen Analysis

Human semen quality in the new millennium: a prospective cross-sectional population-based study of 4867 men

Jørgensen N, Joensen UN, Jensen TK, Jensen MB, Almstrup K, Olesen IA, Juul A, Andersson AM, Carlsen E, Petersen JH, Toppari J, Skakkebæk NE

BMJ open, 2012

DOI 10.1136/bmjopen-2012-000990 PMID 22761286 PMC PMC3391374

RRM Academy Synopsis

Only 23% of young Danish men had optimal sperm quality

A cross-sectional study of 4867 young men from the general Danish population found that only 23 out of 100 had optimal sperm concentration and normal sperm forms. Among fertile men examined earlier, 42 out of 100 did. Sperm concentration and total sperm count rose slightly over the 15 years.

Key Findings

Only 23% of the 4867 men had optimal sperm concentration and normal forms, compared with 42% of 349 fertile men, who were partners of pregnant women examined in 1996–1998.
Median sperm concentration rose from 43 to 48 million/ml and median total sperm count from 132 to 151 million between the 1996–2000 and 2006–2010 groups.
The percentages of motile sperm (median 68%) and of normal forms (median 6.5%) showed no change over the study period.
Sperm concentration in 15% of the men, and normal forms in 35%, fell below levels where the authors say more severe fertility problems may be present. Fertile men had 8% and 18%.
Sperm concentration and total sperm count were lower in the 4867 men than in a 1939–1943 Copenhagen cohort of male partners from infertile couples (p<0.0005 for all comparisons).

Interpretation

The study is a cross-sectional survey. Each man was measured once, and the trend compares different groups of men across years. Participants were young Danes from the Copenhagen area with a median age of 19, and 24% of invited men took part on average. The authors report that the main finding held among the 3921 men without a history of reproductive-tract problems. They note that directly comparable historical data from the general population are lacking. They call for follow-up studies to learn whether the recent upward trend is real biological change or random variation.

RRM Context

The authors conclude that low semen quality seems common among young Danish men and may impair fertility rates. Restorative reproductive medicine evaluates the couple. Both partners are tested, and the cause of a poor semen result is sought before treatment.

Our editorial summary of this paper, not the article's abstract.

Abstract

Objectives

Considerable interest and controversy over a possible decline in semen quality during the 20th century raised concern that semen quality could have reached a critically low level where it might affect human reproduction. The authors therefore initiated a study to assess reproductive health in men from the general population and to monitor changes in semen quality over time.

Design

Cross-sectional study of men from the general Danish population. Inclusion criteria were place of residence in the Copenhagen area, and both the man and his mother being born and raised in Denmark. Men with severe or chronic diseases were not included.

Setting

Danish one-centre study.

Participants

4867 men, median age 19 years, included from 1996 to 2010.

Outcome Measures

Semen volume, sperm concentration, total sperm count, sperm motility and sperm morphology.

Results

Only 23% of participants had optimal sperm concentration and sperm morphology. Comparing with historic data of men attending a Copenhagen infertility clinic in the 1940s and men who recently became fathers, these two groups had significantly better semen quality than our study group from the general population. Over the 15 years, median sperm concentration increased from 43 to 48 million/ml (p=0.02) and total sperm count from 132 to 151 million (p=0.001). The median percentage of motile spermatozoa and abnormal spermatozoa were 68% and 93%, and did not change during the study period.

Conclusions

This large prospective study of semen quality among young men of the general population showed an increasing trend in sperm concentration and total sperm count. However, only one in four men had optimal semen quality. In addition, one in four will most likely face a prolonged waiting time to pregnancy if they in the future want to father a child and another 15% are at risk of the need of fertility treatment. Thus, reduced semen quality seems so frequent that it may impair the fertility rates and further increase the demand for assisted reproduction.

Topics

Male Fertility Semen Analysis Reference Standards

Male Fertility › Semen Analysis › Reference Standards

Niels Jørgensen, Ulla Nordström Joensen, Tina Kold Jensen, Martin Blomberg Jensen, Kristian Almstrup, Inge Ahlmann Olesen, Anders Juul, Anna-Maria Andersson, Elisabeth Carlsen, Jørgen Holm Petersen, Jorma Toppari, Niels E Skakkebæk

N Jørgensen, U Joensen, T Jensen, M Jensen, K Almstrup, I Olesen, A Juul, A Andersson, E Carlsen, J Petersen, J Toppari, N Skakkebæk

PMID 22761286 22761286 DOI 10.1136/bmjopen-2012-000990 10.1136/bmjopen-2012-000990 Jørgensen et al. 2012, Jørgensen 2012

Human semen quality in the new millennium: a prospective cross-sectional population-based study of 4867 men

Only 23% of young Danish men had optimal sperm quality

Key Findings

Interpretation

RRM Context

Abstract

Topics

By this author

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