How concerned should i be with getting pregnant if i only took 3 25mg doses of topomax while on a birth control pill?

Don't worry too much: Hi- topamax (topiramate)'s effect on diminishing the effectiveness of birth control tends to occur at higher doses than 25mg. You should not be too concerned, however if you are remaining on topamax (topiramate) over the long term it would be good to use something other than the pill for birth control-- consider an IUD or depo-provera.