Perhaps you should try some spelling variations:
decreases sperm » decreased sperm (Expand search), decreases serum (Expand search), decreasing sperm (Expand search)
sperm decrease » term decrease (Expand search), speed decrease (Expand search), speed decreases (Expand search)
decrease their » decrease the (Expand search), increase their (Expand search), decreases the (Expand search)
their objects » the objects (Expand search), their objectives (Expand search), their projects (Expand search)
of decreases » of decrease (Expand search), of decreased (Expand search), or decreases (Expand search)
decrease of » decrease in (Expand search)
decrease to » decreased to (Expand search), decrease toc (Expand search), decrease the (Expand search)

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease of decreases sperm decrease ) OR ( decrease to decrease their objects ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease of decreases sperm decrease ) OR ( decrease to decrease their objects ))*.