Pregnant woman sat on the bed taking supplements

Prenatal vitamins: When should you start and how to choose

Written by Karolina Wilde

Karolina Wilde

Karolina Wilde is a sex-positive writer and published author with six years of experience writing about sexual wellness and women's health. She worked with some of the biggest sexual wellness brands in the world and is passionate about the science of how our reproductive system, bodies, and sexuality work and helping people understand these topics better.

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Maja Garbulinska

Maja Garbulinska holds Master’s in Health Data Science from Harvard University. Maja joined Natural Cycles driven by her passion for advancing female and reproductive health. She has several years of experience working with data science and machine learning in Swiss biotech industry.

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Last updated:

Jul 26, 2024

8 min read

Key takeaways:

Often referred to simply as prenatal vitamins, these supplements usually contain a variety of micronutrients including vitamins and minerals
The best time to take prenatal supplements is when you start planning your pregnancy or if you just found out that you're pregnant
Some limited research suggests that supplementing certain micronutrients during pregnancy can prevent pregnancy complications and infant health problems
Key micronutrients to look for in prenatal vitamins are folic acid, iron, vitamin D, and calcium

Planning and preparing for a pregnancy can be a challenging period for everyone involved. It's natural to want to be as prepared as possible and do the best you can to maximize your chances. But with so much information available, it can soon get overwhelming. If you’re feeling this way, know that you’re not alone. In this article, we’ll take a closer look at the science behind prenatal vitamins and supplements and what the guidance is around taking these.

One of the things most people who are planning a pregnancy or just got pregnant are often wondering is: when should I start taking prenatal vitamins, and do I even need to take them? While there is a lot of conflicting information about supplements, most doctors and some research agree that taking certain prenatal supplements can help support a healthy pregnancy.

When should you start taking prenatal vitamins?

There are two instances when you might want to start taking prenatal supplements:

When you decide to try for a pregnancy

If you're thinking about getting pregnant and are planning the steps you want to take to get there, now is a good time to start taking prenatal vitamins. Everyone’s fertility journey is different and how long it takes to get pregnant varies from person to person, so you want to focus on supplements, as well as other preconception care, as soon as possible [1].

You might be wondering why you should bother taking supplements so early. Well, it's no secret that while pregnancy can be one of the most beautiful things you can experience, it's very demanding on our bodies. Growing a fetus into a baby requires a lot of resources, aka vitamins, nutrients, and minerals. By building resource reservoirs of nutrients and minerals, you'll help your body prepare to share those resources with the fetus when the time comes.

When you find out you're pregnant

If you visit a doctor and take a pregnancy test and you find out that you're pregnant, now is also a great time to start taking prenatal vitamins. While taking essential prenatal supplements is important in the early stages of the pregnancy, try not to worry if you find out that you’re pregnant, but haven’t been taking your vitamins yet. Simply speak with your doctor about the best options for you as soon as you can.

Why are prenatal vitamins important?

Prenatal vitamins are designed to aid and support the development of the fetus during pregnancy. They can help prevent pregnancy complications that come with micronutrient deficiencies, such as gestational diabetes and anemia, and infant health problems, such as neural tube defects [2].

There is also some evidence that adequate supplementation might increase fertility in women, but more conclusive research is needed to determine the effects of various mineral deficiencies on our bodies [3].

What are the most important nutrients in prenatal vitamins, especially for the first month of pregnancy?

There are tens of thousands of different supplements available on the market, which can make choosing the right supplement for you a challenging task. We're here to help.

When looking for which prenatal vitamins to choose, there are two things you want to pay attention to: the ingredients and the dosage. Here are some of the key nutrients to look for in prenatal vitamins:

Folic Acid

Folic acid is a form of folate (Vitamin B). It helps our bodies make new cells. Folic acid is essential for the early stages of pregnancy for neural tube development. All people who can get pregnant should take 400 mcg of folic acid every day [4].

Vitamin D

Vitamin D is an essential nutrient that enables our bodies to absorb calcium, one of the main building blocks for our bones. It's also essential for good immune function. Those who are pregnant and breastfeeding need 15 mcg (600 IU) of Vitamin D daily [5].

Iron

Iron is an essential nutrient that helps transport oxygen through the blood to all parts of the body. Iron deficiency anemia affects one in six pregnant women. Supplementing during pregnancy with iron is essential because iron is important for aiding the development of the fetus during pregnancy and decreasing the risk of premature birth. Pregnant women require 27 mg of iron daily [6].

Some research indicates that >25% of people who are pregnant consume too much folic acid and iron, which can have adverse health effects [8]. Before you start taking iron supplement during pregnancy, it’s a good idea to consult your doctor to check on your iron levels.

Calcium

It's recommended that pregnant women who don't consume products high in calcium (such as dairy, tofu, leafy green vegetables [7]) often take calcium supplements (1.5 – 2.0g oral elemental calcium) daily to prevent pre-eclampsia, a complication of pregnancy [8]. For better calcium absorption and to prevent risks like cell damage or hardened arteries, Vitamin D should be taken with calcium [2].

Can you switch prenatal vitamins during pregnancy?

If, mid-way through your pregnancy, you want to switch your prenatal vitamins, it's safe to do so. Not all prenatal supplements are created equally, so if you notice some uncomfortable side effects or you believe the dosage isn't right for you anymore, speak to your doctor to find a better option for you.

How do you choose a daily prenatal?

Sadly, choosing the right daily prenatal vitamin is harder than it should be, and recent research indicates that up to 90% of pregnant women in the US may be at risk of inadequate intake of certain essential micronutrients from their diet, though this percentage varies depending on the specific nutrient and age groups. However, researchers found that over 99% of supplements available on the market don't contain the appropriate dosages of key micronutrients pregnant women need [9].

The authors of the study mentioned above suggest that the large US dietary supplement market might not meet the nutrient needs of pregnant women. The researchers reviewed over 20,000 different supplements available in the U.S. market (prenatal and not), and they only found one supplement (not prenatal) that has all the key nutrients pregnant women need at the correct dosages [9].

When choosing the right prenatal supplement, it's best to speak with your OBGYN. They have experience supporting pregnancies and might help you find the prenatal to supplement your nutritional needs without breaking the budget.

Prenatal vitamin vs. multivitamins

The key differences between a prenatal vitamin and a multivitamin are the ingredients and dosages. Prenatal vitamins are designed with pregnant people in mind and contain key nutrients essential for a healthy pregnancy, such as folate, vitamin D, and iron. These supplements will most likely have a higher dosage of those nutrients, too. Multivitamins are designed for adults and kids and can have a very wide range of nutrients and varying dosages.

Tips for taking prenatal vitamins

If you're ready to start taking prenatal vitamins, here are some of our tips to help you make the experience better:

Consult your doctor: Before you start taking a prenatal vitamin, always consult with your doctor about which type of supplement to take and the dosage. Having the reassurance and support from your doctor will help alleviate the stress and help you find the right supplement for you.
Focus on nutrition: Eating a nutritionally balanced diet full of unprocessed whole foods, even if you take prenatal supplements, is key to supporting your health before, during, and after pregnancy.
Strive for consistency: For supplements to work and for you to experience the full benefit of taking prenatal vitamins, ensure you're taking them consistently. The time of the day doesn't matter as much, but it's important to take them every day for the prescribed period.
Listen to your body: Some prenatal vitamins might make you feel nauseous or cause other physical discomfort. Don't ignore the signs from your body — listen to these signals. Consider adjusting the dose after speaking to your doctor or finding a different type of supplement that makes you feel better. If you feel nauseous after taking a supplement, consider taking it with food or fruit juice.
Increase your fiber intake: Taking prenatal supplements that contain iron might cause constipation [10]. If you experience constipation while taking a prenatal, one thing that can help alleviate it is increasing your fiber intake and making sure your properly hydrating and drinking water. The recommended daily fiber intake for pregnant women is 25-35 mg. Try not to go over board with fiber, because excess fiber might have side effects like nutrient loss and diarrhea [10].

Are there any side effects of taking prenatal vitamins while not pregnant?

The short answer is — it depends. Prenatal vitamins often have folic acid and iron, which are essential nutrients for people who are pregnant or are trying to get pregnant. However, over 25% of pregnant women exceed the maximum intake of iron and folic acid, which can cause adverse health effects [11].

Before you take any sort of supplement, you want to speak with your doctor. They can run the tests to figure out what nutrient deficiencies you have, and find the right type of supplement that fits your individual health and lifestyle needs.

Plan your pregnancy with Natural Cycles

If you are ready to start your pregnancy journey, why not consider giving Natural Cycles a try? Whether your cycle works like clockwork or is less predictable, our algorithm helps predict the best times to conceive, helping you understand your fertility better. Try Natural Cycles yourself today.

References

Vitamins, supplements and nutrition in pregnancy | National Health Service (n.d).
https://www.nhs.uk/pregnancy/keeping-well/vitamins-supplements-and-nutrition/
Adams, J. B., Sorenson, J. C., Pollard, E. L., Kirby, J. K., & Audhya, T. (2021). Evidence-Based Recommendations for an Optimal Prenatal Supplement for Women in the U.S., Part two: Minerals. Nutrients, 13(6), 1849. https://doi.org/10.3390/nu13061849
Schaefer, E., & Nock, D. (2019). The impact of preconceptional Multiple-Micronutrient supplementation on female fertility. Clinical Medicine Insights. Women's Health, 12, 1179562X1984386. https://doi.org/10.1177/1179562x19843868
About folic acid. (2024, May 15). Folic Acid. https://www.cdc.gov/folic-acid/about/?CDC_AAref_Val=https://www.cdc.gov/ncbddd/folicacid/about.html
Office of Dietary Supplements - Vitamin D. (n.d.). https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
Iron-deficiency anemia | Office on Women's Health. (n.d.). https://www.womenshealth.gov/a-z-topics/iron-deficiency-anemia
Food sources of Calcium | Dietary Guidelines for Americans. (n.d.). https://www.dietaryguidelines.gov/food-sources-calcium
World Health Organization. (n.d.). Table 1, WHO recommendation on calcium supplementation during pregnancy for prevention of pre-eclampsia and its complications - WHO recommendation: Calcium supplementation during pregnancy for the prevention of pre-eclampsia and its complications - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK535801/table/fm-ch1.tab1/
Sauder, K. A., Couzens, G. L., Bailey, R. L., Hockett, C. W., Switkowski, K. M., Lyall, K., Kerver, J. M., Dabelea, D., Maldonado, L. E., O'Connor, T. G., Deoni, S. C., Glueck, D. H., & Catellier, D. J. (2023). Selecting a dietary supplement with appropriate dosing for 6 key nutrients in pregnancy. The American Journal of Clinical Nutrition, 117(4), 823–829. https://doi.org/10.1016/j.ajcnut.2022.12.018
Hajhoseini, L. (2013). Importance of optimal fiber consumption during pregnancy. International Journal of Women’s Health and Reproduction Sciences, 1(3), 76–79. https://doi.org/10.15296/ijwhr.2013.13
Bailey RL, Pac SG, Fulgoni VL 3rd, Reidy KC, Catalano PM. Estimation of Total Usual Dietary Intakes of Pregnant Women in the United States. JAMA Netw Open. 2019 Jun 5;2(6):e195967. doi: 10.1001/jamanetworkopen.2019.5967. PMID: 31225890; PMCID: PMC6593963.