How to Choose a Prenatal Vitamin

Most Americans don’t need supplements unless their doctor tells them they have a deficiency in a particular nutrient. But pregnancy is a different ballgame: Pregnant and lactating people have increased nutritional needs compared with others.

Pregnant people have higher micronutrient needs to support the development of the placenta and the fetus while maintaining their own physical health. If not supplemented, your blood levels of most vitamins will decrease during pregnancy. And because the effects of nutrient deficiencies can be particularly dire during pregnancy—preeclampsia and fetal neural tube defects among them—it’s especially important that pregnant people meet their increased nutritional needs.

“Good diet is good, but during this special time, a prenatal vitamin can be helpful to make sure you have all your bases covered,” says Emily Smith, an associate professor of global health and nutrition at George Washington University in Washington, D.C. 

Take iron, for example, which is important for fetal brain development. Consuming low amounts of iron can cause a pregnant person to develop iron-deficiency anemia, which is when a person doesn’t have enough red blood cells to carry oxygen throughout the body, resulting in symptoms such as shortness of breath, weakness, rapid heartbeat, and headache. 

In pregnancy, the recommended dietary allowance (RDA) for iron jumps to 27 mg per day. To get enough iron through your diet alone, “you would have to eat a bunch of livers and, like, five cups of lentils” every day, Smith says. “It’s a very high volume that I find in general is hard to eat—and definitely as you get later in pregnancy and don’t have so much space in your stomach.” On top of that, food aversions might make it difficult for you to eat your leafy greens, whole grains, fresh fish, or other nutrient-dense foods. 

Certain micronutrients, most notably folic acid, are critical to fetal development, and pregnant people need particularly high amounts to support the health of the baby and mom. Adults should consume 400 micrograms of folic acid every day, while ACOG recommends 600 mcg of folic acid a day during pregnancy—400 mcg of which should be from a supplement.

Short answer: As soon as you decide you want to get pregnant. Ideally, you’ll start a prenatal vitamin at least three months before you conceive, or as soon as you find out you’re expecting.

Longer answer: Within the first four weeks of pregnancy. This is because the neural tube, which is the fetus’s developing spinal cord and brain, is one of its first parts to develop. This tube fuses over the spinal cord, spinal tissues (meninges), and spinal nerves, in a process that happens between the third and fourth weeks of pregnancy, often before you even know you’re pregnant. When the neural tube doesn’t close properly, what’s known as a neural tube defect can result, including conditions such as spina bifida (when the neural tube doesn’t completely close over the spine) and anencephaly (when the neural tube doesn’t close completely at the top). Neural tube defects are estimated to occur in about 3,000 U.S. pregnancies each year.

Though neural tube defects are caused by a complex array of factors, healthcare providers and scientists believe that low folic acid intake can play a large role in the development of a neural tube defect in a fetus. Mandatory folic acid fortification in cereal grain products labeled as enriched (such as bread, pasta, and breakfast cereal) became a national requirement in 1998 and is estimated to prevent 1,300 cases of neural tube defects each year. 

But many women in the U.S. still don’t get enough folic acid to prevent birth defects, the Centers for Disease Control and Prevention (CDC) says. 

That’s why it’s key to start taking prenatal supplements—or at least a folic acid supplement—as soon as you find out you’re pregnant, or, preferably, even before. 

If you’re pregnant and haven’t been taking a prenatal vitamin, don’t panic—while neural tube defects are serious, the risk is small. “It’s never too early or too late to start making any sort of nutrition changes,” says Ryann Kipping, MPH, a dietitian who specializes in prenatal nutrition.

Experts agree on the basics of what should be in a prenatal vitamin, and ACOG has specific recommendations for a limited set of nutrients that are considered especially critical for pregnancy. Here’s how each of those nutrients can contribute to your healthy pregnancy and your baby’s healthy development. 

Almost all prenatal supplements include some form of folate—but there’s a lot of confusion when it comes to the best form of folate to take. 

The two most common forms of folate you’ll find in prenatal vitamins are folic acid and methylated folate. Folic acid is the synthetic form of the vitamin folate (aka vitamin B9), which is found in dark leafy greens and legumes. Methylated folate, which you may see on labels as 5-methyltetrahydrofolate (or 5-MTHF), is best understood as a biologically active form of folate. Both folic acid and the folate you get from dietary sources (like lentils and spinach) are converted to the form L-5-MTHF during the digestive process.

Expert groups such as ACOG recommend the use of folic acid in pregnancy over 5-MTHF, because “folic acid is the only type of folate shown to help prevent neural tube defects,” the CDC says. The expert guidance is unlikely to change anytime soon, as the population-wide evidence is considered incontrovertible. To date, there have been no randomized controlled clinical trials studying 5-MTHF for preventing neural tube defects. Why then do some supplement companies use 5-MTHF in their prenatal vitamins?

Essentially, 5-MTHF doesn’t need to be converted in order to be used by the body, whereas folic acid must first be converted to 5-MTHF before it can be absorbed. Some researchers and supplement companies argue that 5-MTHF is therefore more bioavailable than folic acid (meaning more can be absorbed by the body). But this may be an overstatement: While studies have shown 5-MTHF is at least as effective as folic acid at improving levels of folate markers in the blood, 5-MTHF has not been shown to be necessarily more effective than folic acid. Folic acid is also more bioavailable than the form of folate typically found in food. (You may have heard about the MTHFR gene variant and how it impacts folate metabolism, but the CDC states that people with this genetic predisposition can process all types of folate, including folic acid.)

Ultimately, despite some of this emerging research, we simply don’t have clinical evidence yet on the effectiveness of 5-MTHF in preventing neural tube birth defects. There are also questions about the long-term stability of 5-MTHF in supplements. Folic acid is considered more shelf-stable than 5-MTHF, which is why it’s long been used in both supplements and fortified foods.  

In our chart below, we’ve distinguished between the supplements with folic acid and those with 5-MTHF. If you have further questions about the type of folate in your prenatal, your OB-GYN or midwife is your best resource.

When it comes to other recommended nutrients, many of the prenatal vitamins available at your local drugstore or grocery store have lackluster formulations. 

One industry-backed study, published in the journal JAMA Network Open in 2019, found that a significant number of pregnant American women don’t get enough iron, choline, folate, calcium, potassium, magnesium, zinc, and vitamins A, B6, C, D, E, and K—even with the widespread use of prenatals—while another large portion of women were at risk of consuming too much iron and folic acid. (Excessive iron intake can be toxic, and one 2013 study in Nutrition Journal found that it is associated with reduced fetal growth.) The study suggests that “responsible formulation” of prenatals could help.

“If you’re going to a CVS or Walgreens or whatever, and you’re looking at the choices in the store, I think in general most of them are lacking, as far as the quantities and the qualities of nutrients provided,” Kipping says. There are a few nutrients in particular that prenatal supplements tend to neglect. One example is choline, which is important for fetal brain development. “If you go to the supplement aisle and you pick up six random supplements, I would bet most of them wouldn’t have choline in there,” she says. 

Calcium is another heavy hitter that prenatals often lack in adequate amounts, particularly in gummies, says Holly Cummings, MD, an associate professor of clinical obstetrics and gynecology at the Perelman School of Medicine at the University of Pennsylvania. Calcium is important for skeletal development of the fetus and for keeping the pregnant person’s bones strong.

“Calcium’s a really big molecule, so it’s hard to cram into these multivitamins,” Smith says. “And also generally, you don’t want to take it at the same time as your iron supplement.” According to Kipping, iron and calcium can compete for absorption. Some prenatals will include just calcium or iron rather than both; if necessary, the pregnant person could buy an additional calcium or iron supplement and take it at a different time. 

Additionally, iron in prenatals can contribute to constipation and nausea, and one small research study shows that discontinuing prenatals containing iron may ease nausea and other morning sickness symptoms. (Choosing a gel capsule prenatal rather than a hard pill can be easier to stomach if you have nausea, according to Cummings.)

“The supplement industry is hugely underregulated—there’s very little oversight,” Kipping says. That means that there’s no real label verification to ensure what’s in the bottle matches what’s on the label. This is why health experts recommend making sure that your prenatal supplement is certified by a trusted third party.

Third parties, such as ConsumerLab.com, NSF International, UL, and United States Pharmacopeia (USP), “test it for basically purity and truthfulness,” Kipping says. If a company says that certain ingredients or micronutrients are in a supplement and that other ingredients aren’t, the third party verifies those claims. It also ensures the dosage in the supplement matches what is on the label and that a company’s manufacturing and storage facilities comply with good manufacturing practice regulations.

However, it’s important to note that third parties don’t make claims about the safety or effectiveness of the product itself, and that when a company says their products are third-party tested, it doesn’t necessarily mean they’ve been verified by one of the reputable organizations listed above. Kipping recommends checking the packaging or the product website for the seals from NSF International, UL, USP or ConsumerLab.com—we’ve also noted which prenatal vitamins have such labels in our chart below. Here’s a brief guide to what the different third-party labels mean. 

The lack of oversight of the supplement industry also means there are no established limits on the amount of heavy metals allowed in prenatal vitamins in the U.S. A small-scale 2023 study found lead, arsenic, cadmium, and other heavy metals in all six brands of over-the-counter prenatal vitamins tested. One 2025 pre-print study found heavy metal contaminants such as lead and cadmium in all of the 156 prenatal vitamin samples tested, with 83% of the vitamins exceeding the California Proposition 65 threshold for daily lead consumption (0.5 mcg), and 73% exceeding the threshold for cadmium (4.1 mcg), though the study authors have a disclosed interest in third-party testing services. “Clear and enforceable regulations regarding frequent testing and restriction of lead and cadmium contamination in prenatal vitamins are needed,” they write. 

But until stronger regulations take shape, third-party certifications can help close the gap. The benefits of taking a prenatal vitamin still outweigh any potential risks, so your best bet is to look for supplements with third-party seals, which means they’re more likely to contain what’s on the label and be tested for contaminants, though not all third-party certifiers test all products for heavy metals. If you’re looking to dive deeper, it could be worth requesting a certificate of analysis (COA) from a supplement company that’s third-party tested for more insight into their heavy metal testing.

Giving birth doesn’t necessarily mean your nutritional needs go back to baseline. “We generally recommend taking a prenatal vitamin the entire time somebody is lactating or breastfeeding,” says Cummings.

The World Health Organization recommends that breastfeeding people continue taking a prenatal vitamin while breastfeeding, according to Penn Medicine. Some evidence shows that doing so can help the baby’s brain development.

“If somebody is not breastfeeding, there aren’t really any guidelines, and so it would be reasonable to stop after delivery,” Cummings says.

When comparing supplements to find the best one for you, prioritize those micronutrients that ACOG says you need, as well as any that your doctor finds you may be deficient in. Remember that if a supplement does not deliver all the micronutrients recommended by ACOG, you can often get the rest of what you might need from your diet.

None of the supplements in our charts contain ACOG’s recommended daily amounts of every single recommended micronutrient. Some, however, come closer than others; as you’ll see, the prices vary widely, as well. Don’t panic if your budget is limited; what’s most important is that you take a prenatal supplement, and eat as varied and healthy a diet as you can.

“When my patients ask me, I say get any prenatal vitamins that you feel you can afford,” Cummings says. “More expensive is not better.”

Basically: Don’t stress. Conception, pregnancy, and breastfeeding are hard enough as it is. This article, including the graphic below, is meant to empower you to make a more informed choice, not to make you anxious about buying the most perfect prenatal possible. Clearly, there is no perfect prenatal supplement, just like there’s no perfect pregnancy. Do what you can, stay in touch with your healthcare provider, and take things one day at a time.