Many companies here in Canada do not pay out maternity leave. Well, the majority of companies I have worked for anyhow. Your other option is to, if eligible, apply for UI but you need to meet the minimum requirements.
http://www.hrsdc.gc.ca/cgi-bin/hrsdc...6/page03.shtml
Unfortunately, I don't know what companies would pay out if they did pay maternity leave, but UI pays a percentage of what your monthly income was.
It's one option anyhow to look into. Not sure how they treat those with working visas.
Good luck and wish you a happy and healthy pregnancy.