Methods for treating male sub-fertility by administering a pharmaceutical composition to a subject in need thereof are provided. The pharmaceutical compositions include an agent that causes a reduction in an effect of extracellular DNA on sperm cells. The agent may be, for example, an enzyme that degrades DNA such as DNase, a substance that blocks the interaction between cell free DNA and sperm cell surface receptors, a substance that binds to DNA, a substance that inhibits endogenous sperm cell DNase, a substance that inhibits a member of a signal transduction pathway mediated by DNA binding to sperm cell surface receptors, or an agent that stimulates production of an endogenous substance that causes a reduction in an antifertility effect of cell free DNA on sperm cells.
