Table 1. Decline in reference values of semen parameters from WHO 1999 to WHO 2010 guidelines.

Parameter	WHO 1999	WHO 2010	% Decline
Volume (mL)	2	1.5	25
Concentration (million/mL)	20	15	25
Motility, %	50	40	20
Normal forms, %	14	4	71
Live forms, %	60	58	3