Prescription Prenatal Vitamins?

I got pregnant through FET and went to see OBGYN for the first time after seeing RE. He prescribed me prenatal vitamins that cost $700 for 90 tablets!!!! I just got my insurance and I’m not sure if it will be covered as already Walgreens said they don’t cover when I went there. Does any of you r taking prescription vitamins? I don’t know why he prescribed it.