Everything You Need to Know About Prenatal Vitamins

While most health and nutrition experts think taking a multivitamin is a waste of time and money for the majority of people, one important exception is women who are pregnant or planning to become pregnant.

A healthy diet is still important for both mother and baby's health and development, of course. But diet alone doesn't always provide enough of certain nutrients that a successful pregnancy requires. Taking a vitamin specifically tailored to the needs of pregnancy, under a doctor's supervision, is almost always a good idea.

"The goal is to balance getting enough nutrients to support the growth of your fetus and maintaining a healthy weight," says Dr. Mazen Fouany, an OB-GYN with White Plains Hospital Physician Associates in White Plains, New York.

Why Is Diet Sometimes Not Enough?

Pregnancy is a period of intense fetal growth and development, as well as maternal physiological change. "Adequate intake of macronutrients and micronutrients during pregnancy promotes these processes, while undernutrition and overnutrition can be associated with adverse pregnancy outcomes. Therefore, it is important to evaluate, monitor and, when appropriate, make changes to improve maternal nutrition both before and during pregnancy," Fouany says.

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Women who routinely eat three meals daily that include several servings of a variety of vegetables, fruits, whole grains, low-fat dairy products and protein likely meet the Daily Recommended Intakes for most nutrients, Fouany says. "However, even nutrient-dense food choices and diets, such as those in the United States Department of Agriculture food patterns, may not meet nutrient goals for iron, vitamin D and choline during pregnancy. If you're pregnant or hoping to conceive, prenatal vitamins can help fill any gaps."

For example, the typical diet has about 100 micrograms of iodine. "We recommend 220 during pregnancy, so it's very tricky to get double the amount in diet," says Dr. Scott Sullivan, an OB-GYN specializing in maternal-fetal medicine and an associate professor at the University of South Carolina. Additionally, common pregnancy issues like nausea, heartburn and lack of appetite can get in the way. "Women aren't eating three giant meals a day because they don't feel like it," he says. "They need consistency across all nine months of pregnancy," which is where vitamins can help.

When Should You Take a Prenatal Vitamin?

Prenatal vitamins are made specifically for pregnant women to give their bodies the vitamins and minerals needed for a healthy pregnancy. One of those vitamins, called folic acid or folate, should be taken well before any planned pregnancy occurs.

Folic acid can prevent birth defects that affect the baby's brain and spinal cord. These so-called neural tube defects develop early in pregnancy, before many women know they're pregnant. Fouany says that half of all pregnancies are unplanned; "This is why doctors recommend that any woman who could get pregnant take 400 micrograms of folic acid daily, starting before conception and continuing for the first 12 weeks of pregnancy."

During pregnancy, each vitamin and nutrient plays a role in baby's development. Iron, for instance, is used to build the placenta and baby's blood supply. Calcium goes toward bone formation. "You can go down the list of nutrients, and each one has purpose," Sullivan says.

Does Every Pregnant Woman Need a Vitamin?

Yes, with a few precautions. During pregnancy, the growing baby gets all necessary nutrients from mom. "So, you may need more during pregnancy than you did before. Vitamins and minerals play important roles in all of your body functions. Eating healthy foods and taking a prenatal vitamin every day should supply all the vitamins and minerals you need during pregnancy," Fouany says.

What Should a Prenatal Vitamin include?

Fouany says that, at a minimum, the daily supplement should contain key vitamins and minerals that are often not met by diet alone, such as:

-- Iron: 27 milligrams.

-- Calcium: 1,000 mg.

-- Folate: at least 0.4 mg (0.6 mg in the second and third trimesters).

-- Iodine: 150 mcg.

-- Vitamin D: 200 to 600 international units.

"In addition to these key ingredients, pregnant women need to get adequate amounts of vitamins A, E, C, B vitamins and zinc," Fouany says. Work with your physician or a registered dietitian to evaluate your diet and supplement needs.

What Precautions Should Women Take?

Some vitamins can be toxic to the mom, baby or both if too much is consumed:

-- Vitamin A. Excessive amounts of vitamin A can cause birth defects in the fetus's skull, face, limbs, eyes and central nervous system. "Pregnant women should avoid multivitamin or prenatal supplements that contain more than 5,000 international units of vitamin A," Fouany says. Doses greater than 10,000 international units per day appear to be most likely to cause defects.

-- Iron. Too much iron, either from a prenatal vitamin or a separate iron supplement, can cause blood levels of iron to rise too high, possibly causing blood and gastrointestinal problems for mother and baby. Strive for no more than 45 milligrams of iron a day.

Also, be careful when buying prenatal vitamins -- or any vitamins, for that matter. "A lot of patients find this surprising, but vitamins are largely unregulated," Sullivan says. "Many have plastics and lead in them. Many are mislabeled. I tell people to be cautious and generally recommend sticking with known brands with established reputations."

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Sullivan also suggests discussing vitamin options with your doctor before buying them, or bringing the already-purchased bottle in for the doctor to review. And if the mother's insurance will cover it, the doctor can write a prescription for a prenatal vitamin that can be both lower in cost and better in quality, Sullivan says.

Should Prenatal Vitamins Be Continued After Delivery?

Yes. "It's recommended to continue the vitamins after the delivery, especially if the mother is breastfeeding or has vitamin deficiency, a vegetarian diet or lives in an area where vitamin D deficiency is common due to lack of sunlight," Fouany says.

Sullivan recommends women who are not breastfeeding to continue on their prenatal vitamins for six to 12 weeks after delivery. Those who are breastfeeding should continue until they stop breastfeeding, he says.