F1 to H4 Visa COS


I am currently on my F1 visa, and I am about to finish my first semester (Fall 2014). Due to personal reasons I would like to apply for a COS to the H4 visa.
While I know this can be done, my question is: do I need to maintain my F1 status while the H4 application is being reviewed? Ideally I would like to take a leave of absense from my MS before the beginning of next semester, but I am not sure if this can be done without having the H4 approved.

Can anyone please advice regarding this situation.