Dear Human Resources Officer,
I would like to file an early maternity leave, starting on [insert date here] and I will be returning to work after my due date on [insert date here].
I am experiencing pregnancy complications related to my blood pressure levels and I have been advised complete bed rest by my obstetrician. Attached is my doctor's letter of necessity.
Please consider my request with utmost urgency.
Thank you very much.
More sample Maternity Leave letters here