The lunar and menstrual cycles are 4 weeks but there's no link.
And I bet this thing about women affecting each other's cycles is tosh as well. What' s supposed to happen? I've heard people say their cycles line up but there's always a chance this will happen anyway, menstruation isn't always a perfect 4-week cycle and with the odd day or two here and there it's not unlikely women will come into phase with each other.
PS Rufio your 2nd 'affect' was correct, the 1st one was wrong and should've been 'effect'.