How to Choose a Prenatal Vitamin

| Posted On Dec 06, 2021 | By:

Dr. Lilja Stefansson, OB/GYN at Atrius Health, answers sensitive questions with straightforward answers.

Dear Dr. Stefansson, I am trying to get pregnant, and my doctor told me to start a prenatal vitamin. I went to the pharmacy to purchase a bottle, but I ended up so overwhelmed that I left without buying anything! Please help! – PuzzledByPrenatals

Hi PuzzledByPrenatals, you are not alone! Seriously, every time I go to the vitamin section I end up feeling like I am in that scene in Willy Wonka and the Chocolate Factory, where the happy-go-lucky boat ride on the chocolate river turns into an overwhelming, terrifying event! But never fear, by the end of this article, you should feel more confident with picking out a prenatal vitamin.

Did you know that the term “vitamin” is derived from the Latin word vita, meaning “life” and amine for “amino acids,” which are the building blocks for proteins? So these little pills literally help provide the building blocks for life. That’s pretty deep. Importantly, however, vitamins are synonymous with “supplements” and should be used to supplement a well-rounded, healthy, nutritious diet, and not replace anything in your diet.

What makes a prenatal vitamin a prenatal vitamin?

Folic Acid

First off, the most important vitamin is folic acid (a form of vitamin B9). Folic acid is vital in forming the embryo’s neural tube, which occurs very early in pregnancy (sometimes before you even know you are pregnant). The neural tube is the precursor to the brain, spinal cord, skull, and spine (these are pretty darn important structures of the human body, wouldn’t you say?). Given this, the Centers for Disease Control & Prevention (CDC) recommends that those of reproductive age take a prenatal vitamin with 400mcg – 800mcg of folic acid. Prescription prenatal vitamins may contain 1000mcg of folic acid. The amount of folic acid you need may differ based on your medical history. For example, if you have a prior pregnancy that was complicated by a neural tube defect, you will need a higher dose of folic acid (4000mcg). Additionally, if you have any medical conditions such as obesity, diabetes, or epilepsy, a dose of 1000mcg may have some benefit. I strongly recommend you talk with your reproductive health clinician to review what dose is appropriate for you.


Iron is crucial for the healthy development of the fetus and placenta and is also necessary for the development of red blood cells and the prevention of anemia. Did you know that the body gains ~1L of blood by 36 weeks of pregnancy? So yes, please make sure you are getting 25-30mg of iron daily! You also need that extra blood because at delivery—you guessed it—there will be some expected blood loss. There is a downside to iron in prenatal vitamins: it can worsen constipation and/or nausea (which is usually already an issue in pregnancy). One tip to circumvent this side effect is to take your prenatal vitamin at night, so you are sleeping through the nausea if it occurs. You can also take a stool softener like docusate to help regulate your bowels.


We often think of the typical American diet consisting of an exorbitant amount of salt containing iodine, but did you know that half of the women in the United States do not have an adequate dietary intake of iodine? Iodine deficiency is the most common cause of preventable intellectual disabilities worldwide, as iodine is important in the development of the fetal brain (once again, a crucial organ!). And here is where it gets tricky, not all prenatal vitamins contain iodine, and it is recommended that you find one that has 150mg. With so many supplements out there, you need to make sure to take a prenatal vitamin that has iodine in the form of potassium iodide, not kelp.

Tablets vs. Capsules vs. Chewables

Tablets do not contain a coating, so these can be more difficult to swallow. I hear from many patients that the proverbial “horse pill” can be challenging to consume.

Capsules have a smooth coating which can make them easier to swallow. Enteric-coated pills may employ marketing that says they improve absorption, but really there is no benefit to absorption as long as your prenatal vitamin has the essential ingredients discussed above.

I do not recommend chewables because they contain added sugars and do NOT contain iron. Chewables should be reserved for those who truly cannot swallow tablets or capsules but need the folic acid. You will need to remember to take an iron supplement and also brush your teeth! (Remember that good dental hygiene is important in and out of pregnancy).

Legit or not?

Vitamins are not regulated by the Food and Drug Administration (FDA). So, how do you know that you are actually getting the nutrients that you need? Pro-tip: look for the United States Pharmacopeia (USP) Verified Mark on the bottle to ensure that the pills contain what the label reports. Every year consumers in the United States spend over $35 billion (whoa!) on supplements, and some studies have found that many supplements do not contain the main ingredient listed! That should be fraud, but without any regulation, all I can do is educate you on what to look for when purchasing vitamins (Cue: Willy Wonka on the chocolate riverboat singing).

Prescription or Over-the-Counter?

If you prefer, you can ask your clinician to prescribe a prenatal vitamin for you. Prenatal vitamins are typically inexpensive and covered by most insurance. As mentioned before, prescription prenatal vitamins may contain 1000mcg of folic acid in the pill, which is fine. On the other hand, some people prefer to buy their own (think about the whole tablet and capsule thing, for example), and the information you learn here will help you make an informed decision.

In Summary

If you remember nothing else, remember this: make sure the prenatal vitamin you choose has the three key ingredients (folic acid, iron, and iodine) and the USP Verified Mark on the bottle.

And ultimately, PuzzledByPrenatals, when I asked one of Atrius Health’s brilliant clinical pharmacists, Dr. Joy Leotsakos, for any words of wisdom (in addition to her expert input on this topic), she encourages, “Talk to the pharmacist. They will come to the aisle and help you.” So, if you need more help even after reading this article and still feel stressed out like the passengers with Willy Wonka, do not hesitate to reach out to your friendly neighborhood pharmacist. It is what they spent years training to do. And as always, please make sure you have spoken to your reproductive health clinician about your nutrient needs before, during, and after pregnancy, as this will help guide which prenatal vitamin you should get.

View more articles written by Dr. Stefansson on our blog.

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About Dr. Lilja Stefansson

Dr. Lilja Stefansson (she/her/hers) is a board-certified obstetrician-gynecologist. She did her residency at Virginia Commonwealth University, where she was known as the “Queen of Contraception,” and she loves nothing more than being able to help provide her patients with the knowledge and ability to control their reproductive lives. She loves this so much she completed a fellowship in Complex Family Planning from the University of Chicago. Her other clinical interests include adolescent gynecology, management of abnormal bleeding, and the general care of patients throughout their reproductive lifetime and beyond. In her spare time, you can find her in the garden with her husband, three human babies, and two fur babies.