not necessarily worried but certainly concerned. not all birth control pills are the same. one size does not fit all. you may just need an adjustment in your dosage; basically a different pill so you will not be annoyed by this breakthrough bleeding. call your medical provider.
i have had my period three times in the last month and am on birth control could this be natural or should i be worried. the cycle does not follow my normal cycle normally it lasts only a few days and is light. through this is lasts 6-8 days at a time and is often very heavy.