Table 1. Studies showing a decline in semen parameter values (total sample size=18 109).

Year	First author	Sample size	Study period	Location	Major findings
1995	Auger¹⁹	1351	1973–1992	France	1. Mean volume: no change.
					2. Mean sperm concentration declined 2.1% per year from 89 million per ml to 60 million per ml.
					3. Percent motile sperm decreased 0.6% per year.
					4. Percent normal sperm decreased by 0.5% per year.
1996	Irvine²⁰	577	1984–1995	Scotland	1. Sperm concentration fell from 98 million per ml in older cohort to 78 million per ml among donors born after 1970.
					2. Total motile sperm count fell from 169 million to 129 million.
					3. Concentration declined 2.1% per year.
					4. Motility increased 0.18% per year.
1996	Adamopoulos²¹	2385	1977–1993	Greece	1. Total sperm count declined from 154.3 million to 130.1 million.
					2. No significant drop in semen volume.
1998	Bonde²²	1196	1986–1995	Denmark	1. Median sperm concentration dropped from 63 million per ml in men born 1937–1949 to 52 million per ml in men born 1970 and later.
					2. Median total sperm count dropped from 206 million and 117 million respectively.
1999	Bilotta²³	1068	1981–1995	Italy	1. 31% decline in sperm concentration over the study period.
					2. 8% decline in motility.
					3. 9% decline in sperm with ‘typical morphology'.
2003	Almagor²⁴	2638	1990–2000	Israel	1. Sperm count declined by 5.2 million each year.
					2. Motility declined by 0.5% per year.
2005	Lackner²⁵	7780	1986–2003	Austria	1. Study population was infertile men
					2. Decline in sperm concentration from 27.75 million per ml in 1986 to 4.60 million per ml in 2003.
2012	Splingart²⁶	1114	1976–2009	France	1. No decline in semen volume.
					2. Decrease in total sperm count from 443 million in 1976 to 300 million in 2009.
					3. Motility declines from 64% to 49%.
					4. Decline in percent of ‘normal forms' from 67% to 26%.