This is not ‘special maternity leave’ as provided under the Fair Work Act 2009 (Cth) (FW Act) – special maternity leave requires that the employee be unable to work at all due to a pregnancy related illness.
If a pregnant employee cannot perform her job safely because of pregnancy-related illness, but has capacity to perform some work you should transfer her to a safe job (which may include part time work or alternative duties). If you don’t have the ability to provide a safe job for her then you should place this employee on paid ‘no safe job leave’.