When I was pregnant with twins, my doctor recommended I get a prenatal pill that has the highest amount of Folic Acid.
I went shopping and found a few. At walmart they carried Centrum which had a bottle of 100 tablets for 20$.
They also had Equate, also at 100$ and half the price. So I got two bottles for the price of one.
They didn't made my stomach upset like some prenatal pills do.