my friend's guru wrote to her about why women aren't given brahma gayatri mantra, and her guru tole her:
"The nature and constitution of ladies is most favourable to render loving, sweet services, but if they engage in unfavourable practices, the effect will be reversed and they will develop opposite qualities. They will become filled with false ego and the desire to control others, and moreover, they will want to demand respect. If you want to develop all these qualities you may chant brahma gayatri."
qu: why can't women chant brahma gayatri?
a: because it makes them heard-hearted if they chant it during menstruation!
qu: but what about women who don't menstruate (like elderly vaisnavis)?
a:
qu: when is a human body ever really pure then? what if a man has a sticky plaster on his finger? can he chant brahma gayatri?
qu: um. what about prabhupada....?