Hey female frontend engineer here from Melbourne, Australia. I've been coding for about 5 years now and from what I have noticed (change roles every 1-2 years), women don't get pushed into frontend, they choose to.
I do find backend developers tend to be older and the frontend crowd usually younger. At least that's been my experience over the last decade or so working in the middle in the APAC region. That might also have something to do with it.
Hey, thanks for your response! YLD is a software engineering and design consultancy (https://www.yld.io/), we like to do research and studies into interesting topics in STEM and actually should have an article coming out soon on womenlovetech.com which actually has australian origins so you may be familiar with it!
EDIT: Also to thee OP, what's YLD?