You are already on leave, and as such, there is no possibility of resigning from the position while away from work, literally. Once the maternity leave is over, you have to resume duties, and later you may opt to resign, but not otherwise. Remember, you still have to hand over the work to another employee as per the company policy, and the notice period has to be served unless the management decides to waive it. You cannot have your cake and eat it too; there is no question of taking maternity benefits after resigning. Once the employee resigns, the benefits are no longer applicable. The government has initiated the policy to provide enough rest to the mother and child, and employers are obliged to implement it. Trying to manipulate the benefit scheme to suit your career while still wanting the benefits is not acceptable.
Thanks and Regards