Kirbay, actually the maternity payment is not income tested. Everyone no matter how much they earn will recieve the $3000/$4000 payment and then if you stop work, or decrease your hours at work the gov will give you a baby bonus of about $500 at tax time for the child for the first five years, you can only claim for one though.

taken from the Family assistance website:

Note: It recognises the extra costs incurred at the time of a new birth or adoption of a baby and is not income tested.

My DH systematically earns between $110-$150K a year and we get it.
Ta Dee