Sep 14, 2023 | Pregnancy

The Ultimate Guide to Prenatal Vitamins

It’s probably not news to you that you should take a prenatal vitamin.

Many OB/GYNs encourage taking one before you are pregnant, and it’s certainly addressed at the first appointment. But beyond “you should take one,” do you really know how to choose one? How do you determine what the best supplement regime is for YOU and your pregnancy?

I’m so glad you asked.

There is a lot to consider in this process. If you’re a TL/DR kind of girl (that’s ok!), jump to the end where I share my favorite brands with links to order. (Some are affiliate links, which means that I may earn a small commission, at no extra cost to you.) But if you’re a “give me all the research and let me make my own decision,” then buckle up. Here we go.

Why Should I Take a Prenatal Vitamin?

First, let’s talk about WHY you should take a prenatal vitamin. Being grounded in the benefits and purpose make taking it each day a little easier.

Taking the right prenatal supplements can:1

  • Reduce nausea, heartburn, and fatigue throughout your pregnancy
  • Support labor, delivery, and healing
  • Aid in breastmilk production
  • Help you rebuild and repair so you are ready for future pregnancies should you choose
  • Help result in a healthy baby!

Keep in mind I’m sharing info based on my general recommendations. But there can be many individual considerations when choosing a prenatal. If you have any medical conditions, a high-risk pregnancy or a history or nutrient deficiencies (e.g., anemia, vitamin D, etc), then I recommend a one-on-one consultation to ensure you’re getting a customized protocol for the best possible results.

The Role of Supplements

First, it’s important to remember that supplements are – by definition – meant to supplement your diet. They are intended to be part of the health picture, not the whole thing.

Second, remember that supplements are not regulated by the FDA. There are no required approval processes of supplements like there are for drugs. This is why it is SO important to find a trustworthy brand that evaluates their products for both purity and potency, ensuring what’s on the label is what’s in your supplement.

When should I start taking a prenatal vitamin?

Probably before you’re reading this (sorry!). Ideally 3-4 months before you conceive, or as soon as you get a positive pregnancy test.

Continue taking your prenatal all through your pregnancy and at least the first 6 weeks postpartum to support recovery. If you breastfeed, continue the prenatal for one month after you stop nursing/pumping.

Is it possible to get too many vitamins and minerals during pregnancy?

Yes! The old adage “if some is good, more is better” is not true here. Having too much of certain vitamins or minerals can be toxic and (in extreme cases) even fatal. Problems occur when you mix and match individual vitamins, or take more than the recommended dosage. In other words, don’t cherry pick advice from Google to determine what to take.

Jump to recommendations

Vitamins in Prenatal Vitamins

Vitamin A

The most important thing to look for when it comes to vitamin A is the form of the nutrient. Too much synthetic or preformed vitamin A can cause birth defects, so it is important to get vitamin A from mixed carotenoids or beta carotene and palmitate.

Look for 5,000 IU/day, but do not exceed 10,000 IU/day in supplement form due to potential toxicity.2

Note: you cannot cause defects or overdose simply by eating foods high in vitamin A or beta carotene. The issue is only with over-supplementation.

Vitamin B6

Low B6 levels can be common in pregnant women since your growing baby demands a good amount of it, and not everyone starts pregnancy with adequate stores. If you’ve taken oral contraceptives prior to conception, you are at an increased risk of deficiency. Bonus: B6 can also help with nausea.3 Your prenatal should contain at least 10 mg of vitamin B6.

Vitamin B9 (Folate)

The most well-known pregnancy-related nutrient because of its direct link to neural tube defects and other complications.4

Folic acid is the synthetic form of the nutrient folate. Some research estimates up to 40% of women have a genetic abnormality that prevents them from converting folic acid into methylfolate (the active form the body needs).

For that reason, unless you have done genetic testing and know for sure, I recommend looking for a prenatal that contains 600-800 mcg of methylfolate and/or folinic acid.

Vitamin D

Despite many studies that indicate the Recommended Daily Intake (RDI) for vitamin D is too low, many practitioners won’t encourage taking more. The current RDI is 600 IU per day, but up to 4,000 IU has been shown to be safe in pregnancy, and even beneficial. No prenatal has close to this.

It is a good idea to have your baseline vitamin D checked as deficiencies at the start of pregnancy are linked to an increased risk of gestational diabetes, pre-term birth, preeclampsia, postpartum depression, and bacterial vaginosis.

A deficiency of vitamin D increases the baby’s risk of low calcium and stunted growth all the way through the first year of life.

I generally recommend at least 2,000 IU per day during pregnancy and 6,000 IU per day during breastfeeding. Depending on your vitamin D status at conception, you may need more.

Jump to recommendations

Minerals in Prenatal Vitamins


Most prenatal multivitamins contain no choline, however it has been linked to placenta function, decreasing the risk of gestational diabetes and preeclampsia, along with improving cognitive function in children.5

Since choline is a large mineral, it requires either very large pills or multiple pills. Most pregnant women say “no thanks” to those options, so manufacturers often just leave it out. Therefore, separate choline supplementation is needed for most women to reach the goal of 450 mg per day.

Of course, choline through diet is possible, but it’s hard for most women to get unless they are eating 2-3 eggs per day.


Iodine is necessary for thyroid function and brain development, and poor intake can impact both mom and baby. Even a moderate deficiency during pregnancy increases risk for lower IQ and reading ability.6

Iodine is added to table salt to prevent deficiencies, but Americans get most of their salt from processed foods, and are choosing Himalayan sea salt that is not iodized.

It is recommended that pregnant and breastfeeding women supplement with at least 150 mcg of iodine to help meet daily needs.


Iron needs increase during pregnancy, and due to food aversions, getting enough can be tricky. Your OB/GYN may monitor your levels to avoid deficiency. Most women need 20-45 mg/day through supplementation.7

Iron can affect the absorption of other nutrients, so it’s best to supplement separately (prenatal in am and iron in pm, for instance). Additionally, iron can be constipating—so look for those easiest on the stomach: iron picolinate or iron bisglycinate.


Magnesium needs increase during pregnancy but it is estimated that pregnant women get about half of what is needed.8 Magnesium is involved in metabolic health, blood pressure regulation, blood sugar control, bowel health, stress management and muscle health.

Magnesium citrate and magnesium glycinate are easiest on your stomach, and are good options to improve sleep and reduce leg cramps. Magnesium oxide is the cheapest form of magnesium and is recommended for bowel regularity.

Other Supplements

Omega 3s and DHA

DHA, a type of Omega 3, is important for fetal eye, brain and neuron development, as well as healthy brain function in moms. A deficiency in DHA has been linked to anxiety in women and developmental delays in babies.9

DHA is most abundant in fish and seafood, which many women often limit due to mercury concerns (note: based on the research, I do not agree with this approach).

The prenatal multivitamins that do contain Omega 3 fatty acids usually don’t have enough to meet your needs. I recommend supplementing with at least 300mg of DHA and a similar amount of EPA as well.

NOTE: quality, testing and purity is SO IMPORTANT with fish oil. Otherwise, there are concerns with rancidity of the oil and contaminants like heavy metals.


Glycine plays a role in growth and development of your baby’s bones, organs and DNA, as well as your own circulation, uterus, and placenta.10 During both pregnancy and postpartum your glycine needs increase, but for the most part it can be addressed with food.11 Ironically, it is found in foods that many consider “unhealthy” like tougher cuts of meats slow-cooked with the bones in or poultry cooked with the skin on. Bone broth and collagen supplements are other good sources.


Consider certain bacterial strains that have been shown to have pregnancy-specific effects. Lactobacillis rhamosis and Lactobascillus reuteri may reduce rates of Strep B.12

Final Considerations

The highest quality prenatal vitamins are divided doses (i.e., more than 1 pill per day). Yes, it is more of a pain to take, but it does improve absorption of the nutrients, and may be easier on your stomach.

To ease nausea associated with taking prenatals, consider splitting the doses over the day, taking the vitamins with meals (especially those containing protein or fat), or opting for a chewable or powder form.


This reference tool is simply about educating women on the role supplements play during their pregnancy journey, where nutrient gaps may lie and why quality is important. While I make recommendations on specific brands, please remember that no prenatal vitamin is perfect. Please be in contact for specific advice related to your individual situation. This is not a substitute for any medical advice.

Prefer to access a full range of professional grade supplements? Join my FullScript dispensary.

Order supplements through my Fullscript store.


  1. Garner CD, et al. Nutrition in pregnancy. Accessed Aug 15, 2023. ↩︎
  2. Bastos Maia S, Rolland Souza AS, Costa Caminha MF, Lins da Silva S, Callou Cruz RSBL, Carvalho Dos Santos C, Batista Filho M. Vitamin A and Pregnancy: A Narrative Review. Nutrients. 2019 Mar 22;11(3):681. doi: 10.3390/nu11030681. PMID: 30909386; PMCID: PMC6470929. ↩︎
  3. Matthews A, Haas DM, O’Mathúna DP, Dowswell T. Interventions for nausea and vomiting in early pregnancy. Cochrane Database Syst Rev. 2015 Sep 8;2015(9):CD007575. doi: 10.1002/14651858.CD007575.pub4. PMID: 26348534; PMCID: PMC7196889. ↩︎
  4. Jouanne M, Oddoux S, Noël A, Voisin-Chiret AS. Nutrient Requirements during Pregnancy and Lactation. Nutrients. 2021 Feb 21;13(2):692. doi: 10.3390/nu13020692. PMID: 33670026; PMCID: PMC7926714. ↩︎
  5. Derbyshire E, Obeid R. Choline, Neurological Development and Brain Function: A Systematic Review Focusing on the First 1000 Days. Nutrients. 2020 Jun 10;12(6):1731. doi: 10.3390/nu12061731. PMID: 32531929; PMCID: PMC7352907. ↩︎
  6. Harding KB, Peña-Rosas JP, Webster AC, Yap CM, Payne BA, Ota E, De-Regil LM. Iodine supplementation for women during the preconception, pregnancy and postpartum period. Cochrane Database Syst Rev. 2017 Mar 5;3(3):CD011761. doi: 10.1002/14651858.CD011761.pub2. PMID: 28260263; PMCID: PMC6464647. ↩︎
  7. Peña-Rosas JP, De-Regil LM, Garcia-Casal MN, Dowswell T. Daily oral iron supplementation during pregnancy. Cochrane Database Syst Rev. 2015 Jul 22;2015(7):CD004736. doi: 10.1002/14651858.CD004736.pub5. PMID: 26198451; PMCID: PMC8918165. ↩︎
  8. Luke B. Nutrition During Pregnancy: Part I, Weight Gain; Part II, Nutrient Supplements. JAMA. 1991;265(2):281–2. ↩︎
  9. DiNicolantonio JJ, O’Keefe JH. The Importance of Marine Omega-3s for Brain Development and the Prevention and Treatment of Behavior, Mood, and Other Brain Disorders. Nutrients. 2020 Aug 4;12(8):2333. doi: 10.3390/nu12082333. PMID: 32759851; PMCID: PMC7468918. ↩︎
  10. Avagliano L, Garò C, Marconi AM. Placental amino acids transport in intrauterine growth restriction. J Pregnancy. 2012;2012:972562. doi: 10.1155/2012/972562. Epub 2012 Jul 11. PMID: 22997583; PMCID: PMC3401547. ↩︎
  11. Rasmussen BF, Ennis MA, Dyer RA, Lim K, Elango R. Glycine, a Dispensable Amino Acid, Is Conditionally Indispensable in Late Stages of Human Pregnancy. J Nutr. 2021 Feb 1;151(2):361-369. doi: 10.1093/jn/nxaa263. PMID: 32939556; PMCID: PMC7850138. ↩︎
  12. Ho M, Chang YY, Chang WC, Lin HC, Wang MH, Lin WC, Chiu TH. Oral Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 to reduce Group B Streptococcus colonization in pregnant women: A randomized controlled trial. Taiwan J Obstet Gynecol. 2016 Aug;55(4):515-8. doi: 10.1016/j.tjog.2016.06.003. PMID: 27590374. ↩︎

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I’m Katie Goldberg (AKA The Pregnancy Dietitian), mom of 2 little humans, health coach, and registered dietitian nutritionist. I can guide you through the research and best practices (and avoid all the B.S.) to help you confidently nourish your body and your baby during this unique season of life.

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