Prenatal Vitamins: What They Contain and Why You Should Take Them

What are prenatal vitamins?

Prenatal vitamins are specially formulated supplements to help give your baby essential nutrients for healthy development. During pregnancy, your required daily intake of certain vitamins and minerals increases – and it’s not easy to get these amounts through diet alone.

Benefits of Prenatal Vitamins

Most women can benefit from taking a prenatal vitamin and mineral supplement (preferably before trying to conceive). Think of it as an insurance policy to make sure you’re getting the right amount of certain essential nutrients during pregnancy.

It’s hard to get all the nutrients you and your baby need, even if you eat a wide variety of foods, including meat, dairy, fruits, vegetables, grains, and legumes.

Taking a prenatal vitamin is even more important for women with dietary restrictions, health issues, or pregnancy complications. This includes women who:

  • Are vegetarian or vegan
  • are lactose intolerant or have other food intolerances
  • Smoking or abusing other substances
  • Have certain blood disorders
  • Have an eating disorder
  • Have certain chronic illnesses
  • Have had gastric bypass surgery
  • Having twins or higher multiples

Prenatal vitamin ingredients – what to look for?

Two key nutrients – folic acid and iron – are almost always included in prenatal vitamins because most pregnant women don’t get enough from food alone.

Folic acid

Getting enough of this B vitamin in the month before conception and very early in your pregnancy can reduce your baby’s risk of neural tube defects, such as spina bifida and anencephaly, by up to 70%. Folic acid may also reduce the risk of other defects, such as cleft lip, cleft palate, and certain heart defects. Taking folic acid can even reduce your risk of preeclampsia.

Your body absorbs the synthetic version of folic acid better than the natural version found in food, so even if you eat a balanced diet, a supplement is highly recommended.

For more details, see our full article on folic acid in your diet during pregnancy.

The iron

Most moms-to-be don’t get enough of this mineral in their diets to meet their body’s increased needs during pregnancy, which can lead to iron deficiency anemia. Preventing iron deficiency anemia can reduce the risk of preterm birth, low birth weight, and infant mortality.

For more details, see our full article on iron in your pregnancy diet.

Find out your due date and see how tall your baby is right now.

What other nutrients should I look for in a prenatal supplement?

Your provider can recommend a good prenatal vitamin and may also suggest additional supplements to take, depending on your diet and other health factors. Common nutrients pregnant women may need to take in supplement form include:


Your prenatal vitamin may contain calcium, but it may not be enough. You need calcium to help your baby develop strong bones and teeth as well as healthy nerves and muscles (including the heart).

Most prenatal vitamins contain between 100 and 200 milligrams (mg) of calcium, but some do not. That’s because calcium is a particularly bulky mineral, and the pills are big enough already!

To find out how much calcium you need and how to get it, see our full article on getting calcium in your diet during pregnancy.

Essential fatty acids

Prenatal vitamins generally do not contain essential fatty acids, such as omega-3 fatty acids DHA and EPA, which are important for the development of your baby’s brain, nerves and eye tissue.

Fish is a major source of DHA and EPA, but you should be careful not to eat too many mercury-rich fish during your pregnancy.

Because omega-3s are so important for your baby, it’s a good idea to talk to your healthcare professional about whether you need a supplement.

Learn more:

Vitamin D

Your body needs this fat-soluble vitamin to help build your baby’s bones and teeth. Vitamin D plays an important role in maintaining calcium and phosphorus levels.

If you’re low on vitamin D during pregnancy, your baby may be low on the vitamin when it’s born. This can put your child at risk for rickets (which can lead to broken bones and deformities), abnormal bone growth and delayed physical development. Vitamin D deficiency has also been linked to an increased risk of developing pregnancy complications such as preeclampsia and gestational diabetes, but more research is needed to confirm these links.

To find out how much vitamin D you need and how to get it, see our full article on vitamin D in your diet during pregnancy.

Other nutrients

Some other vitamins and minerals that may be good to have in your prenatal vitamins include iodine (which may help keep your thyroid healthy during pregnancy) and choline (necessary for your baby’s brain growth. ).

When should I start taking prenatal vitamins?

Take a prenatal vitamin every day as soon as you realize you are pregnant.

Since folic acid is so important in the first weeks of your pregnancy, you should ideally start taking prenatal vitamins. before you conceive – that’s why many doctors recommend them for women who might become pregnant. And if you’re breastfeeding your baby, your doctor may recommend that you continue taking prenatal vitamins even after your baby is born.

Choosing a prenatal vitamin – what’s right for me?

Unfortunately, no standard has been set for what should be in vitamin and mineral supplements because the Food and Drug Administration does not regulate them. That means it’s up to you and your healthcare professional to make sure you choose one that’s safe and appropriate for you. (See our article on buying supplements for more tips.)

During your first prenatal exam or during a preconception visit, your practitioner will likely prescribe a daily vitamin or recommend an over-the-counter brand.

A good addition:

  • Provides certain nutrients that you may not be able to get enough from your diet. The exact nutrients and amounts needed will depend on your individual eating habits. At a minimum, look for these key nutrients
    Folic acid/folate: at least 400 mcg
    Iron: 27mg
    Calcium: 1000mg
    Vitamin D: 200 to 600 IU
  • Does not provide more than the recommended amounts other nutrients that can be harmful to your baby if you take too much – such as vitamin A. (Vitamin A derived from animal products can cause birth defects when taken in high doses. It is why the vitamin A in most prenatal vitamins is at least partly in the form of beta-carotene, a nutrient found in fruits and vegetables that your body converts into vitamin A and is considered safe even in high doses.)

To note: Be sure not to take any other vitamin or mineral supplements while taking a prenatal supplement, unless your doctor recommends it.

Not sure which prenatal vitamins to choose? Check out these best prenatal vitamins and supplements. Consult with your provider first to ensure that any supplement you take during pregnancy is suitable for your unique needs.

What happens if I mistakenly take two prenatal vitamins on the same day?

Do not worry. Taking twice the recommended amounts of these nutrients in one day will not harm you or your baby. But taking a double dose more often can be harmful, so it’s important not to do it regularly.

If your practitioner tells you that you need more of a certain nutrient than your prenatal vitamin provides, take the extra amount as a separate supplement.

What if I have trouble swallowing the pills?

Prenatal vitamin and mineral supplements tend to be quite important. They can be difficult to swallow, especially if you suffer from nausea.

If this is a problem for you, your practitioner may be able to recommend a smaller pill or one with a smooth coating that makes it easier to come down. (Pills that don’t contain calcium tend to be smaller, and you can get your calcium in other ways.)

Chewable prenatal vitamins are also available. There is even a powdered pregnancy supplement that you mix with water. So if you don’t like one version, keep trying different options until you find a prenatal supplement you can take.

Do prenatal vitamins have side effects?

Most women do not experience side effects from taking prenatal vitamins, but some complain of:


If you take a supplement with more than the recommended 30 mg of iron, it can upset your gastrointestinal tract. (Supplements that contain 30 mg or less probably won’t cause you any problems.)

To avoid nausea, try taking your supplement at bedtime or with a meal to make it more tolerable. Also talk to your healthcare professional. She may be able to recommend a different prenatal supplement.


Taking a lot of iron can lead to constipation, which is already a problem for many pregnant women.

If you’re not anemic, it may be a good idea to switch to a prenatal vitamin with less iron. Alternatively, try to relieve constipation by:

  • Drink prune juice
  • Eat two to three servings of fruit a day
  • Take a psyllium fiber supplement
  • Take a stool softener, such as docusate sodium

Remember that even if you take prenatal vitamins, you still need to eat well.

Discover the basics of healthy eating during pregnancy.

Patricia J. Callender