My mother, who is a midwife, recommended I start taking pre-natal vitamins as soon as we got married....just in case!
They are really just like regular vitamins, but have more folic acid and more iron. They are very safe and good to take. I actually take mine in the evening, before bed, and I don't get stomach upset from them. 400 mg of folic acid is all you need when looking for which prenatal vitamin to take. And, they turn your pee a fun shade of bright yellow....LOL