But if male sperm counts are dropping (and they are, at least in most industrial / post-industrial societies), how is that accounted for? It takes two to tango

But if male sperm counts are dropping (and they are, at least in most industrial / post-industrial societies), how is that accounted for? It takes two to tango when it comes to pregnancy, sans a fertility clinic, eh. Doesn't the lack of accounting for it (i.e., sperm counts falling) corrupt the legitimacy of this method? That is, what stat is the female equivalent of sperm count? That cacan physical become pregnant / have children but via whatever method choose not to.