I think the law says (others can jump in and correct me if they want) that women are entitled to 3months paid maternity leave, starting from 1 month before their due date. If you can afford that it would be the nice thing to do.
As for what you do while she is gone, she may have a friend she could train to take her place while she is gone. Of course, the friend will need to be paid too, so if you are on a budget paying two full maid salaries may be a bit of a hardship. But you may be able to work something out like paying the replacement a lower salary and/or not paying a full salary for the original maid while she is on leave.
Be prepared to be asked for one or more large loans to cover expenses such as the midwife, 40-day parties, etc.