I think it depends on the type of birth control pill you're taking.. i've been on them all - pills, patch, shot, 28 day pills, 90 day pills and continual (no periods). I also take coumadin - before and after my AVR, they were concerned with my blood pressure.. they weighed the clotting issue against any other risk factors that I may have.. the lower dose pills and the mini's with no estrogen.. there are many options available now (IUD with low hormones is now available as well), depends on why you need to take them.. birth control or medical.. I was both..
my issue with the synthetic birth control are the side affects.. if it was a possible side affect, I had it.. i'm 4 years post op, went back on BC within 6mnths of AVR.. went off 3 years later - it's now been 7 months and i'm just now finally getting it out of my system.. 3yrs of BC, 40 lbs heavier then my goal weight.. (25lbs of that just from being on the depo shot last fall) and all the side symptoms that come with that.. high BP..etc.. it's coming off slower then it went on, but the weight is coming down.. 15lbs so far.. 25 more to go..
my point, I know I went off subject a bit.. I prefer natural therapies when possible.. there are just as many birth control options which are natural and don't have the side affects as there are types of synthetic BC.. whether you need hormones for BC or medical, there are natural resources to help both what won't put you in a higher risk for clotting or other nasty side affects..
feel free to PM me if you have a interest in those natural therapies..
Chris