In Australia, employment laws are such that any woman who has a baby is allowed to have 12 months maternity leave (without pay). If she returns before the 12 months is up, that is her decision. When she returns, she is guarranteed to have the same job at the same pay. If she decides she wants a part-time job, or different work, then it is to be decided between her and her employer.
Some of the larger firms are now offering up to 6 weeks paid maternity leave (with the remainder of the time to be unpaid).
Also paternity leave is now an option, with some companies offering up to 12 months unpaid leave.