Topamax & Birth Control: Understanding Potential Interactions During Pregnancy

Question
I had my last period around April 12.  I skipped my May cycle using my Birth Control for a vacation.  I then had unprotected sex around what would have been an ovulation day if I were not on the pill.  My concern is that I am on the medication Topamax for migraines at a low dosage (100 mg) and my doctor told me it won't affect the effectiveness of my birth control.  I want to make sure this is true because I am getting a brown discharge and am wondering if it's dried blood from skipping my last period with my pills or if I could be pregnant and the Topamax could be affecting my birth control's ability to keep me from ovulating.  I was prescribed birth control because of a latex allergy and was told that my birth control was just as effective as a condom for me as long as I knew who I was sleeping with and got tested for STD's regularly.  I need to know if this is true.  Tomorrow will be the last day of my pack and I don't want to throw off my cycle by stressing over a possible pregnancy if my doctor was right in the fact that my Topamax should not affect the Birth Control at such a low dosage.  Thanks.

Stefanie

Answer
Topamax does not lower the efficacy of the pill. The pill is 99.9% effective against pregnancy. Everything that your doctor claimed, is correct. A brown discharge is not an indicatiion of pregnancy but rather is a sign of "old blood" from a previous period that is still in the uterus. It has nothing to do with pregnancy. The earliest signs of pregnancy are breast tenderness, fatigue, and nausea. Don't worry. Remember that the blood you get when you finish a pack of pills is really only a "breakthrough bleed" due to lowering of your hormonal level. Since you continued the pills in order to delay your "period" from starting, your hormone level did not drop and you did not bleed. It is really not a "period".