Will birth control lighten my period?

In the past, I've had heavy bleeding(even clots). A year after my first period, I was but into the hospital after a massive hemorrhage... guhhh. For two years I had heavy periods, and then it was so-and-so for another two years. Then soon my heavy periods came back. I asked my doc., and he put my on some birth control pills. I've taken my first pack so far, and I'm hoping after the third pack my flow will lighten. Will birth control lighten my periods to the point where I won't bleed heavily anymore. I just want this nightmare blood-hell to end.