The best way to meet your nutritional needs is through a healthy, balanced diet.  However, you may still be missing some key nutrients.  Prenatal vitamins help to ensure pregnant women get the extra vitamins and minerals needed for the development of a healthy baby.  They also help to meet your nutritional needs when trying to conceive and while breastfeeding.
Prenatal vitamins provide the same nutrients as standard multivitamins with extra folic acid and iron.  Folic acid is a B vitamin that helps to prevent neural tube defects – abnormalities of the brain and spinal cord. There is also evidence that supplemental folic acid during pregnancy may also lower the risk of other abnormalities like cleft lip and palate and heart defects. Taking folic acid may also decrease risk factors for preeclampsia. Iron is a mineral and is often deficient in the diet.  Supplemental iron aids in the production of hemoglobin, prevents anemia and decreases the risk of low birth weight babies and premature delivery.
Taking a prenatal vitamin is especially important for women with special diets and food intolerances and for women with health concerns.  Women who have had gastric bypass surgery may have trouble absorbing nutrients or meeting their nutritional needs through diet alone and will require supplementation.  Prenatal vitamins are also especially important for women pregnant with two or more babies or at increased risk for complications during pregnancy.
When considering which prenatal vitamin to take, look for a vitamin that contains 400-800mg of folic acid, 250mg of calcium, 30mg of Iron, 50mg of Vitamin C, 15mg of Zinc, 2mg of Copper, 2mg of Vitamin B6 and 400 IU of Vitamin D.
Keep in mind that prenatal vitamins do not replace a healthy diet.  In addition to your daily prenatal vitamin, you may also consider adding a supplement of Omega-3 fatty acids DHA and EPA, which are important for brain, nerve and eye development.
Talk with your provider at your next office visit about your specific needs and concerns to determine the right supplements for you.