After the FIRST one; either tie the tubes or all the other little bastards are on you!
Social engineering has already been tried. Hitler did it and eventually failed.
A smaller but also offensive part of his extermination plan was to kill as many Roman Catholic priests as possible. They disapproved of his plans.
Let the females continue to breed but give them NO MONEY for any babies born after the first one. THAT would do the trick more than anything else.
Most sensitive spot on any human: wallet