Neuro/molecular/chem ~= biology and is similar to each other for the most part.
women are underrepresented in almost all major engineering fields. It's not like the math there is harder than pure maths or that it's more challenging. Just different.
stats is its own beast. Accounting is very different from computers-related fields or biology for example. Statistics classes are also pretty much evenly balanced.
pure math is also very different from everything else. It might be in some cases similar to theoretical CS/applied math but to get to theoretical CS most people have to go through undergrad CS classes that paint a completely different picture of what that work is like.