Prenatal Vitamins

I just recently had my annual checkup and my doctor and I talked about taking vitamins. She recommended I start taking some folic acid but that I could also take just a prenatal vitamin, in case birth control failed. That way I would be healthy and ready to go if I was pregnant. I was doing some research though and I read a lot about being careful taking prenatal vitamins if you aren't pregnant or TTC.  Should I worry about taking them or could I take them every other day or something?