I have used birth control pills since I was about 16. I am now 22. I don't have sex very often, so after I started taking the pills I quit for about two years because I was not having intercourse. When I began having sex again I got back on the pill, but it was a different brand. This happened again and again over the years -- I would stop taking them (because I wasn't having sex, or because of problems like spotting), then start later with another brand. Now I'm on the Depo-Provera shot. My friends say I may be messing up my system by stopping and starting and changing brands and methods. Could I be harming my fertility by doing this? What side effects or damage could occur from switching birth control methods like this?

D.D.

There is no reason to believe that switching pills or starting and stopping is harming your system. Depo-Provera can result in prolonged suppression of ovulation and menses for a period of up to one year after the last injection. It is also frequently associated with weight gain of two to four pounds each year.
However, there is also no reason to believe that you would be better off by getting off the pills when you are not sexually active. In fact, there are other non-contraceptive benefits of the pills -- such as stronger bones, fewer ovarian cysts and breast lumps -- that make it advisable just to stay on the pill. Of course, cost and any side effects may affect that decision, too.

It sounds like you have changed partners over the years. Please consider the use of condoms in addition to birth control pills, to avoid sexually transmitted disease as well as unwanted pregnancy.