Prenatal Vitamins..Help! ?

Ok so I went in for a doctors visit just to confirm my pregnancy and after being confirmed giving me some details on what to next the doctor gives me a prescription for some prenatal vitamins and I'm assuming they're off brand because I can't really find anything about them on any website really. The name of them are Preplus tablets , and I don't know how much and what is actually in the vitamins so should I stop using those and just get some over the counter vitamins or continue taking them, I mean I hope I can trust what the doctor has given me. Ughhhh what should I do? ?