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If you eat a healthy diet when pregnant, why do you need to take prenatal vitamins?

"Even for a woman who eats a 'perfect' diet, it is nearly impossible to get some of the nutrients in the amounts needed during pregnancy, such as iron and folic acid," Bridget Swinney, MS, RD, author of Eating Expectantly, explains in an email interview. For women who don't eat all their greens, prenatal vitamins are a kind of "insurance policy," providing them with the nutrients they may be missing from diet alone.

For example, you need more iron right now because your blood volume expands during pregnancy. Iron is an essential component of hemoglobin, the substance that carries oxygen in your blood. If your diet doesn't include enough iron-rich foods, like red meat, egg yolks, and dark leafy greens, your body will pull it from the reserves in your bone marrow. You can become anemic. Iron is especially important during the last trimester of pregnancy, when the baby's needs are the greatest, says Roy Pitkin, MD, who chaired the National Academy of Sciences' Committee on Nutritional Status During Pregnancy and Lactation.

Folic acid is absolutely critical for cell division, and for preventing neural tube birth defects such as spina bifida and anencephaly. It's best to start taking it at least one month, preferably longer, before you get pregnant and throughout your pregnancy. Health experts recommend that all women of childbearing age take daily multivitamins containing at least 400 micrograms of folic acid because pregnancies aren't always planned.   

Here are some of the vitamins and minerals and amounts you'll find in prenatal vitamins, and why your baby needs them:




Why You Need It


250 mg

Builds strong bones and teeth


450 mg

Develops memory and learning center in the brain


200 mg

Promotes fetal brain development

Folic acid

600 mcg

Enables cell division and prevents neural tube birth defects


250 mcg

Important for proper brain development


27-60 mg

Helps with the production of new blood cells to accommodate increased blood volume during pregnancy

Vitamin D

600 IU or more

Builds strong bones and teeth, and used for making hormones


Why Can't You Just Take a Multivitamin?

"A prenatal vitamin has the amount of nutrients that more closely match the nutrient needs of a pregnant woman," says Swinney. "Some may also have things that regular multivitamins don't have, like DHA [an omega-3 fatty acid] and choline, which are particularly important for fetal brain development."  

Do You Need to Buy Prescription Prenatal Vitamins?

You can buy prenatal vitamins right over the counter at your local pharmacy. Or you can get a prescription from your ob-gyn, midwife, or family doctor. You'll typically pay more for prescription prenatal vitamins. Yet they do supply an extra vitamin and mineral boost. "Prescription prenatals tend to have more vitamins and minerals included, or more of certain nutrients than an over-the-counter brand," Swinney says. You may find more folic acid (1,000 micrograms instead of the 400 micrograms in over-the-counter versions) and iron in prescription prenatal vitamins and supplements, as well as added nutrients like iodine, choline, magnesium, and copper.  

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