Though it may be tempting to forgo taking those daily pills, prenatal vitamins are an important part of prenatal care. You need a to maintain a well balanced diet to support your body's changes and your baby's growing needs. Vitamins like folic acid are essential to your baby's brain development and your heath as well. You need iron because of your increased blood supply needs and the needs of the baby and placenta. A deficiency could mean you'll get anemia. So don't skimp. It's best to be sure that you're maintaining your nutritional needs rather than risking any deficiencies.
Always check with your doctor to find out what vitamins are best for you.