Late Period While on Birth Control and Fioricet: Is Pregnancy Possible?

Question
I am on birth control (falmina) and also take fioricet for headaches. I am four days late for my period and have taken 3 pregnancy tests that have all been negative. I have not missed any pills and cant remember if I took any of the fioricet for headaches. I am afraid the fioricet has made my birth control less effect. I have no symptoms of pregnancy but am worried I could be pregnant. Am I pregnant and should I be worried?

Answer
I don't think you need to worry.  Some women miss periods or stop having periods on the pill.  As long as your pregnancy test is negative, I would just keep taking the pill as usual.  If you miss your next period, you could ask your doctor to change pills, but it's not harmful having no periods on the pill, and some women prefer it.