Aging; Your Pregnancy Matters

Which prenatal vitamins should I take?

Aging; Your Pregnancy Matters

To reduce the risk of your baby having spina bifida start taking folic acid two to three months before conception.

I recently had a colleague ask me about prenatal vitamins. She and her friends were confused by conflicting advice they’d received from their physicians and read on the Internet. She wasn’t even pregnant yet, but someone had suggested she start taking a prenatal vitamin.

They had a lot of questions, like most women do: What prenatal vitamins should I take? Should I take a multivitamin even if I eat a healthy diet? How much of each vitamin should I take? How early should I start taking each supplement? Are there vitamins I should avoid? What is best: over-the-counter, prescription, synthetic, or whole food vitamins?

But the answer is simple: If you are an average, healthy woman who eats a healthy diet, don’t get bogged down in worrying about all the multivitamin information out there. Most women need just two supplements: folic acid and iron.

Folic acid

Studies have shown that receiving adequate folic acid in the first four to six weeks of pregnancy can reduce the risk of spina bifida, in which the closure of the spinal cord has been interrupted. Because it is crucial to get this supplement so early in the pregnancy – even before you may realize you’re pregnant – start taking 400 mcg (0.4 mg) of folic acid each day for two to three months before conception. If you have had a child with spina bifida from a previous pregnancy, your physician will recommend a higher dose.

Even if you and your partner are just starting to talk about having a baby, you should start taking folic acid. There is no harm in taking it when you’re not pregnant, so it’s better to get in the habit in taking the vitamin to ensure folic acid is in your system when you start trying to conceive.

If you discover you are pregnant unexpectedly and have not been taking folic acid, don’t panic. A number of foods such as breads and cereals are supplemented with folic acid. You likely have been getting some in your diet, although you should begin taking a folic acid supplement right away and continue taking it throughout your pregnancy. It’s especially important for women carrying twins or triplets to continue folic acid to help produce the extra blood volume needed in those pregnancies.


Women need extra iron during pregnancy to build up their blood volume in preparation for the blood loss that comes with delivery. Unless you are anemic, I tell patients not to worry about taking an iron supplement until they are out of the first trimester.

This is for two reasons:

  1. The demand for extra blood volume really doesn’t increase much until after the first trimester; and
  2. Iron can be poorly tolerated and can contribute to nausea and vomiting, symptoms you may already be experiencing during the first trimester!

Pregnant women should get about 30 mg of iron a day during pregnancy and continue taking it for a few weeks after birth to help the body quickly return to a normal blood volume. If you have a history of iron deficiency anemia you may need to start building up your blood volume earlier than the second trimester or may require more iron supplementation, so talk to your physician.

Prescription or over-the-counter prenatal vitamins?

Some women think they need a prescription prenatal vitamin, which can cost $60 to $90 a month, depending on your insurance plan and pharmacy benefits. Folic acid and iron supplements cost pennies a day. You don’t need a prescription for them; an over-the-counter, generic version will work just fine. As long as you can tolerate one of the over-the-counter supplements, put the money you would have spent on a prescription into a college fund for your baby (or stock up on diapers!).

Combination prenatal supplements also include a variety of vitamins. If you choose a product that includes multiple vitamins, make sure to look at which fat-soluble vitamins – vitamins A, D, E, and K – it contains and how much. The one we tend to worry about in pregnant women is vitamin A, which when taken in excess has been linked to an increased risk of birth defects. Think about what other sources of vitamin A you may have in your diet, including drinks like smoothies with extra vitamin supplements. If you eat a healthy diet, you likely will not need to take additional amounts of these vitamins.

In the past few years we’ve see many prenatal vitamins add decosahexaenoic acid (DHA) to their formulations. DHA, an omega-3 fatty acid, is a chemical is necessary for brain and eye development in infants. It was thought that fetal exposure – via a prenatal supplement – would possibly result in better outcomes for children. But results were released in 2014 that showed children at age 4 who were exposed to DHA during the prenatal period did no better on tests of general cognitive function and language than those whose mothers did not take the drug prenatally. So I don’t feel that women have to take a vitamin with DHA added.

As for whether you should look for a synthetic, whole food, or organic prenatal vitamin, the decision is up to you. I think you need to find a version your body tolerates- despite your best intentions, you just won’t take a medication that has unpleasant side effects. If you are a vegetarian, you may want to take a second look at the source of its ingredients. For example, if you really want a prenatal vitamin that includes DHA, it may come from a fish-based product, but there are algae-based products available also.

Side effects from prenatal vitamins

Folic acid doesn’t seem to cause problems; at least I’ve never had a patient tell me it made them feel unwell. Iron, on the other hand, can cause nausea and constipation in some people.

Taking iron with food can help lessen the nausea. As for the constipation, some iron supplements have stool softeners such as docusate added to them. You also could take a separate stool softener or add extra fiber or prune juice to your diet.

Here are a few tips to make taking prenatal vitamins easier:

  • Formulation: A little difference in the formulation of the vitamin can make a difference, so try a couple different products to see which works best for you.
  • Timing: Most people take vitamins in the morning. If it’s making you nauseated, try taking it before bed so the effects of the nausea won’t stay with you all day.
  • Get it in another form: If you do not want to take a pill and you are dedicated, you may be able to get enough iron and folic acid in the foods you eat. Folate-rich foods include fortified cereals and breads, lentils and dark green vegetables such as broccoli and asparagus. Iron rich foods include red meat, pork, poultry, seafood, beans and dark green leafy vegetables such as spinach. Cold, citrusy drinks often taste good to women with morning sickness, so you might be able get a vitamin additive in your smoothie.

For the average woman considering pregnancy, start taking folic acid two to three months before you conceive, and an iron supplement after the first trimester. That’s all most women need. If you know you are deficient in some vitamins, talk to your physician about what further supplements you may want to consider.