Dear Nehasinhaoss
In good and big organization the Performance appraisal system and process does not get affected by an individual on Maternity Leave.
Thus, if the absence is during the performance period then last or average ratings are prorated for the period.
Similarly; the Date of Increment is UNIFORM across the organization and employees.
Thus the Date of Increment will remain the SAME.
The employee will draw Salary or Leave with Wages accordingly.
This is the general policy all over in good and reputed companies.
However, small companies or those with dubious policies may change it according to suit their requirements.
Warm regards.