With due respect and honour I would like to inform you by the first week of xx/xx/xxxx, my wife is going to have delivery at xxxxxxxx.
I therefore, kindly request you to grant me Rs. xxxxxxxx as salary advance for my wife delivery and it to be repaid with a deduction from my salary of xxxx per month. I need your Kindly approval in this regard. I’ll be thankful to you for this kindness.