I was told I had to take my maternity leave first, unless I wanted a longer break before the baby was due. The AWA for my work sets out that we have to take maternity leave from 6 weeks before your due date, unless a medical practitioner approves us working later, and we have to start it some time before the due date either way. I am taking some annual leave afterwards though.

Stefnie, what your work has done sounds a bit dodgy to me, I'd get it checked by a union rep or something (if you have one).