What is the best over-the-counter prenatal vitamins?

There aren't any: Pregnant women need lots of Folic Acid and otc vitamins don't contain enough Folic Acid to meet a pregnant woman's needs. Folate (folic acid) helps prevent certain congenital spinal problems.

Trial and error.: You can decide for yourself which brand best suits your needs and causes the least nausea/stomach upset; many of my patients like the walgreen's prenatal vitamins. Centrum specialist prenatal vitamins are probably the best product.