When to start taking prenatal vitamins (and the benefits of starting earlier)

last updated: Mar 24, 2021

5 min read

If you're a planner and kids are on the horizon, you might be thinking ahead about how you can set yourself up for the healthiest pregnancy possible. Part of that includes building up your reserves of pregnancy-supporting nutrients, using a combo of balanced eating and prenatal vitamins.

But when do you have to start taking prenatals to ensure you're getting recommended levels of essential nutrients by the time you're pregnant? And is there any harm in taking them months (or even years) before conception?

We'll answer these questions (and many more) in this article, but before we jump in, here's the most important takeaway up front: Prenatal vitamins with folate are recommended at least one month before conception — and you can even replace your daily multivitamin with a prenatal (depending on the formulation).* 

Modern Fertility

Get proactive about your reproductive health

First things first: Why is taking a prenatal vitamin so important?

We're all about taking a food-first approach to nutrition. That's because foods are more than the sum of their nutrient parts — all of the vitamins, minerals, antioxidants, and fibers in whole foods work together for your optimal health.

However, many nutrients essential for a healthy pregnancy aren't readily available from food alone — like vitamin D, choline, and the omega-3 fatty acid DHA. These particular nutrients are not only more scarce in the food supply, but they're also needed in higher quantities during pregnancy and lactation (whether or not you're breastfeeding/chestfeeding).

Even in resource-rich countries, people with ovaries typically don’t eat enough of some of the most essential micronutrients for pregnancy. Here are three important examples:

That's where prenatal vitamins come in. In general, supplements are kind of like the wild west — there's minimal government regulation over what gets slapped with the “prenatal” label. But if a prenatal has a good assortment of the nutrients recommended for pregnancy, it can help you bridge the gap between low intake from food and higher nutrient demands.

Try as we may, it’s not always easy to be as nutritious in our food choices as we'd like to be. A prenatal vitamin can relieve some of the stress of trying to do it all perfectly, giving you what we like to think of as a nutritional insurance policy.

When should you start taking a prenatal vitamin?

The American College of Obstetricians and Gynecologists (ACOG) recommends that you get 600 micrograms (mcg) of folic acid (aka folate) each day. Because it’s hard to get this much folate from food alone, they recommend taking a daily prenatal vitamin with at least 400 mcg of dietary folate equivalent (DFE) starting at least one month before pregnancy. That said, the CDC sees value in all people with ovaries taking a prenatal with folate throughout their "reproductive years" to support fetal neural tube (brain, spine, and spinal cord) development in the event of pregnancy.*

If you're deciding between starting a prenatal vitamin one month before conception (per ACOG's rec) or building up your nutrient levels even earlier, keep this in mind: It's tricky to pinpoint exactly when you'll get pregnant. (In fact, it's estimated that almost half of pregnancies are unplanned.) Taking a prenatal months (or even years, depending on the formulation) before conception helps you prepare your body for pregnancy, nutritionally speaking, no matter when that ends up happening.*

What are the benefits of taking a prenatal vitamin before getting pregnant?

Your nutritional needs increase immediately after conception. So, it's important to build up the nutrients in your body before pregnancy to make sure you're getting the most out of all the great benefits associated with prenatals.*

As soon as that egg is fertilized, the embryo starts gobbling up nutrients needed for cell growth and division. Those teeny-tiny organs form in the first eight weeks of pregnancy, and the neural tube (soon to develop into the brain and spinal cord) closes within the first 30 days of gestation — all of this before many people even miss a period or realize they’re pregnant. This means that all of the necessary nutrients must be readily available the moment sperm meets egg.

According to guidelines from leading OB-GYNs, these are the most important nutrients your body needs before and during pregnancy (caveat: each nutrient has tons of benefits, so we've included a few of the most important ones here):

  • Folate (aka folic acid or methylfolate) to support fetal neural tube development*

  • Iron to form red blood cells and hemoglobin — the protein in your blood that transports oxygen from your lungs throughout the body*

  • Choline to support fetal neurodevelopment*

  • Omega-3 fatty acids (DHA and EPA) to help develop the fetal brain and retina*

  • Vitamin C to promote the growth of all connective tissue (skin, joints, etc.) and a healthy immune system*

  • Vitamin A to support fetal eye development and good vision, as well as a healthy immune system*

  • Vitamin B-6 to boost your energy while you're pregnant*

  • Vitamin B-12 to help keep the central nervous system on track*

  • Iodine to help with developing a healthy fetal brain and maintaining thyroid health*

  • Calcium to strengthen fetal teeth and bones

  • Vitamin D3 to promote bone health and improve immune function for you and the fetus*

If you’re vegetarian or vegan, the list of nutrients to pay attention to grows longer. Vegetarians often aren't getting enough ironzincomega-3 fatty acidsvitamin Dcholine, and vitamin B12 from food alone — and vegans are sometimes deficient in calcium as well. Looking for vegetarian or vegan food sources and prenatals that fill your nutritional gaps can help you get your levels where they need to be by pregnancy.

Many prenatals don't include calcium because it can block the absorption of iron and supplementation maxes out at ~500 mg. Both of these factors can make it difficult to put calcium alongside other nutrients in a prenatal. Instead, the Prenatal Multi has a calcium booster: vitamin D.*

The Prenatal Multi also has zinc and biotin. Zinc is essential for healthy fetal growth, and can be up to 50% deficient in vegetarians.* Biotin aids in converting food into energy, and a third of pregnant people are deficient.*

Are there any downsides to taking a prenatal vitamin early?

Let's say you want to get an extra early start on prenatals because you're really into planning ahead. Are there any risks or side effects associated with that? Nope — as long as the nutrient levels in the prenatal, in addition to what you're already getting from what you eat, are beneath the recommended upper limits for nonpregnant people.*

An important nutrient to look out for when you're starting prenatals early is iron. High levels of iron, which are often found in prenatals, can cause gastrointestinal (GI) side effects like constipation, heartburn, and nausea, as well as inhibit absorption of other nutrients. For many people, balanced levels of a different form of iron can help. Research shows that ferrous fumarate and ferrous sulfate lead to the most GI symptoms, while ferrous bisglycinate leads to the fewest.*

Prenatals will list the exact forms they use of each nutrient on the label, so look for ferrous bisglycinate to be extra easy on your tummy. If you're meeting the recommended pre-pregnancy daily iron intake of 18 mg through food alone (this rises to 27 mg during pregnancy), you can also opt for a prenatal without iron.

Modern Fertility's Prenatal Multi has ferrous bisglycinate and the iron level set by the FDA for pre-pregnancy (18 mg) to minimize uncomfortable side effects and start taking it early.* The Prenatal Multi also includes vitamin C, a nutrient shown to improve the absorption of any iron you're already getting.*

Can you just replace your daily multivitamin with a prenatal?

In general, yes! A prenatal multivitamin can replace your everyday multivitamin, but not vice versa. While some prenatals include nutrients that are important whether or not you're pregnant, generic multis don't always include enough of the nutrients you'll need in higher quantities for pregnancy (like choline, folate, and DHA).

If you want to get a leg up on nourishing your body for a future pregnancy, replacing your daily multi with a prenatal can help you fill up those nutritional reserves earlier. Taking a prenatal now, before you’re trying to conceive, is a low-cost, low-risk way to get a headstart on a healthy pregnancy — no matter when it happens.*

*This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

March 24, 2021

Written by

Anna Bohnengel, MS, RD, LD

Fact checked by

Health Guide Team

About the medical reviewer