Prenatal Supplements: All You Need to Know

July 2019

Prenatal Vitamins: What You Need To Know

Pregnancy changes a woman’s body and therefore changes the amount of nutrients she needs on a given day. By taking a prenatal vitamin, a woman can help ensure that she gets the adequate amount of nutrients she needs to support herself and her baby during her pregnancy.

Here’s a run-down of the most essential nutrients commonly found in prenatals:

Folic acid / Folate: If you were just going to take one supplement while pregnant, folic acid would be the one. Not only is this b-vitamin hard to absorb from a natural diet, but it plays a crucial role in preventing neural tube and other birth defects. You should aim to take 400-600 micrograms (mcg) of folic acid a day while you’re trying to conceive and boost your intake to at least 600 mcg daily once you’re pregnant. Due to increased absorption, choose a prenatal supplement that carries the active form of folic acid, L-methylfolate.

Iron: Many women already begin a pregnancy with low iron stores and will need additional iron all throughout the pregnancy. Iron-deficiency is associated with preterm delivery, low birth weight, and infant mortality. Pregnant women need around 27 mg of iron per day, but more is not better—iron in higher doses can be toxic and should be avoided.

Iodine: Even mild iodine deficiency has been associated with declines in cognitive function. Pregnant women should aim to get 200–300 mcg per day.

Vitamin D: Essential for developing a fetus’s bones, this nutrient plays a part in maintaining levels of calcium and phosphorus. Your prenatal vitamin may not contain enough vitamin D as different medical experts recommend anywhere from 600 to 5,000 IU a day. A recent study found women taking 4,000 IU of vitamin D daily had the greatest benefits in preventing preterm labor and infections without any signs of toxicity. Since vitamin D is fat soluble, take it with food for better absorption.

Omega-3 fatty acids: You may not find these essential fatty acids in a prenatal, but they  are critical for fetal neurodevelopment. Pregnant women should aim to get least 500 mg of omega-3s, including EPA and DHA, daily. Our Top of the Line pick contains omega-3s as part of the pack; however, most prenatals don’t include them and you should take them separately.

Magnesium: This nutrient works in combination with calcium to build strong teeth and bones for your baby. Pregnant women should aim to get 300-400 mg of magnesium per day. When choosing a supplement, you should look for magnesium glycinate or magnesium citrate on the label, the forms best absorbed.

Zinc: important for many biological functions including protein synthesis, cellular division and nucleic acid metabolism. Pregnant women should aim to get at least 11 mg of zinc.

Vitamin A: while an important nutrient for pregnancy, this vitamin can come in two various forms, beta-carotene and retinol. Retinol has been shown to cause birth defects in large amounts and you should therefore find a prenatal supplement that contains beta-carotene instead. Pregnant women should aim to get 2 mcg of beta-carotene per day.

Calcium: This essential nutrient can reduce the risk of hypertension, preeclampsia, and preterm birth. If you don’t get enough calcium when you’re pregnant, then your baby will draw it from your bones, which can impair your own health. Pregnant women need at least 1200 mg of calcium per day. Most prenatal vitamins will contain low calcium amounts and you may need to supplement it separately. Be sure to take the calcium supplement at a different time of day then the iron-containing prenatal as calcium blocks the absorption of iron. Choose calcium citrate or malate for higher absorption.

If you choose to take a supplement, be sure to keep track of the daily amounts you take as it’s possible to overdose on certain nutrients, such as iron, calcium, and others.

NOTE: Prenatals are great—but only if you’re pregnant. Women who aren’t pregnant should refrain from taking prenatals because the doses are above the recommended doses for non-pregnant women and toxicity can build up relatively quickly for certain components.

When choosing a prenatal supplement, you should try to find one that has a seal of approval from independent organizations, such as USP, NSF International, and other consumer watchdog groups, to make sure it is manufactured in a cGMP facility and is free of dangerous pollutants. Here at HealthAnchor, we have a very high bar for what we consider a great supplement and what we recommend to our readers – we look at purity, efficacy, absorbability, and proper dosage.

Which is the Best Prenatal Supplement?

Check out our unbiased recommendation of the best products on the market using our rigorous methodology. We screen products for the right formulation, bioavailability, safety, and efficacy to bring you only the best supplements available in 2019.

A Closer Look at Prenatal Supplements

Most women want to ensure a healthy pregnancy and delivery, but it can be hard to get all the essential vitamins and nutrients a baby needs even if the mother consumes a healthy and diverse diet. Just as pregnant and lactating women require more calories, they also require more nutrients.

Prenatal vitamins differ from other multivitamins because they focus on some of the crucial nutrients that pregnant women need for a healthy birth that they don’t get enough of in their diets. Pregnancy causes changes to the body, which then require increases in essential nutrients. For example, pregnancy increases blood flow, requiring more iron than normal for the increased blood in their body. Women who don’t get enough iron are at risk for anemia.[1] Similarly, a pregnant woman needs more calcium, B12, and vitamin D to develop their child’s skeleton and brain. These vital nutrients will immediately go the fetus and if a woman doesn’t get enough of these nutrients, then the baby will begin to leach calcium from the mother’s bones.

Women who consume the right micronutrients are less likely to have incidents of birth defects called neural tube defects, autism, low-birth weights, and premature births.[2] Prenatal vitamins may even help lessen the effects of morning sickness. By taking a good prenatal vitamin that has the doses of these nutrients intended for pregnancy, a woman is able to avoid major health risks to both herself and her fetus.

Folic Acid

Folate, a generic term for a water-soluble B-complex vitamin, is a very important nutrient. While dietary folate can be found in food, folic acid is a synthetic dietary supplement that can only be found in vitamins or fortified foods. Pregnant women who consume appropriate amounts of folic acid are less likely to have a baby born with neural tube defects, such as spina bifida and anencephaly, autism, and diabetes-associated birth defects, and childhood leukemia.[3] Folic acid has also been shown to lower the rate of anemia in the mother and may also reduce the risk of other birth defects, such as cleft lip, cleft palate, and certain heart defects.

As neural tube defects can occur at a very early stage of development, women should begin to take folic acid very early in their pregnancy or before they even conceive. According to the Centers for Disease Control and Prevention (CDC), women who take the recommended daily dose of folic acid starting at least one month before conception and during the first trimester of pregnancy reduce their baby’s risk of neural tube defects by up to 80 percent.[4]

To reduce your baby’s risk of developing a neural tube defect, experts recommend that you take 400-600 micrograms (mcg) of folic acid a day, beginning at least a month before you start trying to get pregnant.[5] Most health professionals and the U.S. National Institutes of Health suggest boosting your intake to at least 600 mcg daily once you’re pregnant. Most prenatal vitamins contain 800 to 1,000 mcg of folic acid, but it may not be fully absorbed.

Different prenatal vitamins may include different sources of folic acid, including either the typical supplemental type of folic acid or the more bioavailable form, L-methylfolate. About 1 in 2 women has a genetic polymorphism that impairs the conversion of the supplemental folic acid to its active form L-methylfolate, meaning they won’t reap the benefits from the type of folic acid most commonly found in most prenatals. If you have a family history of neural tube defects or preterm births, then you may want to try to find a supplement that carries the active L-methylfolate form just in case you also have this genetic polymorphism.

Women who have a family history of neural tube defects may need to consume more than the recommend amount, but should speak with a medical professional before they decide to increase guidelines. Women who are obese appear to be more likely to have a baby with a neural tube defect.[6] If you’re significantly overweight, see your healthcare provider before you try to conceive. She may advise you to take more than 400 mcg of folic acid a day.

There are risks associated with taking too much folic acid and it’s best not to take more than more than 1,000 mcg per day of folic acid without medical instructions to do so. Many women are B12 deficient and too much folic acid can make it harder for a doctor to diagnose that deficiency.

The major natural sources of dietary folate are legumes, green leafy vegetables, liver, citrus fruits and juices, and whole wheat bread, but research shows that a diet high in folate should not replace a vitamin supplement as the folate from food is not easily absorbed. Only 50% of folate naturally occurring in food is bioavailable, while approximately 85% of folic acid supplementation is absorbed when consumed with food, and 100% is absorbed when fasting.[7]

Iron

Even before you’re pregnant, your body needs iron to carry oxygen to other cells, maintain a healthy immune system, and produce myoglobin. As pregnancy increases the amount of blood in the body, a woman needs extra iron to make more hemoglobin. Pregnant women also need extra iron for your growing baby and placenta, especially in the second and third trimesters. Many women need additional iron because they start their pregnancy with insufficient stores of iron. Iron-deficiency is associated with preterm delivery, low birth weight, and infant mortality.[8]

Pregnant women need around 27 milligrams of iron per day. Currently, a low-dose iron supplement is recommended for pregnant women, starting early in pregnancy. Pregnant women should be encouraged to consume iron-rich foods such as lean red meat, fish, poultry, dried fruits, and iron-fortified cereals. Meat and ascorbic acid-rich fruits enhance the absorption of non-heme iron, the type from plants and iron-fortified foods. Foods that inhibit iron absorption, such as whole-grain cereals, unleavened whole-grain breads, legumes, tea, and coffee, should be consumed separately from iron-fortified foods and iron supplements.

Calcium supplements may also inhibit iron absorption and should be taken at a different time than an iron supplement. If your prenatal vitamin contains calcium, some doctors recommend that women take an additional iron supplement, and take their prenatal with calcium at a different time as the iron supplement. As Vitamin C helps the body absorb iron, you may want to take the iron supplement with some fruit rich in this vitamin.

Increasing the doses of iron will not improve the benefits and higher dosages may have potential negative effects on mineral absorption, oxidative pathways, and adverse gastrointestinal symptoms. In some cases, the iron in prenatal vitamins can lead to side effects, such as constipation, gas, nausea, and bloating. You can drink more water and increase the fiber in your diet to avoid constipation.

Calcium

When you’re pregnant, your developing baby needs calcium to build strong bones and teeth. Calcium also helps your baby grow a healthy heart, nerves, and muscles as well as develop a normal heart rhythm and blood-clotting abilities.

Calcium can also reduce your risk of hypertension and preeclampsia neonatal mortality, and preterm birth in developing countries. And if you don’t get enough calcium in your diet when you’re pregnant, your baby will draw it from your bones, which may impair your own health later on.[9]

All women should aim to get 1000 milligrams (mg) a day and pregnant women should aim to get 1200 mg. Try to find a prenatal without calcium, as it likely won’t be enough anyway, and then take the prenatal at a different time as the iron supplement to insure iron absorption.
When it comes to the diet, milk and other dairy products are great ways to consume calcium, as are low-mercury canned fish, such as sardines, calcium-fortified cereal, juice, soy and rice beverages, and breads, but one must check the label to know whether the product is fortified.

Iodine

Iodine can aid in a baby’s thyroid and brain development and even mild iodine deficiency has been associated with declines in cognitive function. World Health Organization guidelines suggest an intake of 200–300 μg/d iodine daily for pregnant women.[10] American Academy of Pediatrics (AAP) recommends that pregnant women take a daily supplement containing 150 mcg of iodine and also cook with iodized salt. If the prenatal supplement you’re considering doesn’t have any iodine, talk to your doctor about taking a separate iodine supplement.

Vitamin D

Vitamin D is important for a fetus’s bones, teeth, and plays a part in maintaining levels of calcium and phosphorus. Usually a doctor will check a pregnant woman’s levels at her first prenatal visit just to be sure she’s not deficient. While optimal vitamin D levels should should be over 25 ng/mL (nanograms per milliliter), 40-60 percent of the U.S. population have a vitamin D level under 30 ng/mL.

The amount of vitamin D you need while pregnant may be influenced by your level of vitamin D deficiency before pregnancy, which is why many experts recommend screening.[11] Even if you’re not deficient, you will still need extra vitamin D throughout your pregnancy. The Institute of Medicine currently recommends that all women, pregnant or not, get 600 IU a day, while the Endocrine Society recommends that pregnant and breastfeeding women need 1,500 to 2,000 IU of vitamin D a day. A recent study found women taking 4,000 IU of vitamin D daily had the greatest benefits in preventing preterm labor and infections without any signs of toxicity.[12]

Women who do not get enough vitamin D during their pregnancy may put their child at risk for rickets, abnormal bone growth, and delayed physical development. A deficiency of vitamin D has also been linked to a greater risk of developing pregnancy complications such as preeclampsia and gestational diabetes.[13]

Omega 3 Fatty Acids (DHA & EPA)

Omega-3 fatty acids are critical for fetal neurodevelopment, the brain, eyes, and nerve tissue, and may be important for the timing of gestation and birth weight.[14] As prenatal vitamins don’t usually contain any essential fatty acids, such as the omega-3 fatty acids DHA and EPA, then you may want to consider adding one to your diet.

Fish is a major source of DHA and EPA, but can be high in mercury and therefore limited while you’re pregnant. The American Dietetic Association and Dietitians of Canada recommend that pregnant and lactating women consume at least 500 mg of omega-3s, including EPA and DHA daily.

Magnesium

Magnesium is crucial for protein synthesis and works in combination with calcium to form bone, protein and fatty acids, helping build strong teeth and bones for your baby. Magnesium helps to relax the muscles and aids in blood clotting. Studies show that magnesium levels are lower in women who have had a premature labour and that magnesium can help to prevent premature births by relaxing the muscles of the womb.[15]

The RDA for a pregnant woman is 300-400 mg per day. When choosing a supplement, you should look for magnesium glycinate or citrate on the label, which is the current best form due to its high absorption and lack of digestive side effects.[16]

Zinc

Zinc is important for many biological functions including protein synthesis, cellular division and nucleic acid metabolism. According to the World Health Organization, an estimated 80 percent of pregnant women worldwide have inadequate zinc levels. Low plasma zinc concentrations reduce placental zinc transport and may affect the supply of zinc to the fetus. Women who do not get enough zinc during their pregnancy are more likely to have preterm births and suffer from intrauterine infections.[17] The RDA for zinc is around 11 mg.

Considerations When Choosing A Prenatal

Taking a prenatal vitamin is even more important for women with dietary restrictions, health issues, or pregnancy complications. This includes women who are vegetarian or vegan, lactose intolerant, smoke, have certain blood or eating disorders.

While some women experience a reduction in morning sickness from prenatals due to an increase in B12, other women can become queasy likely due to an increase in iron. If you experience nausea, you can try taking your prenatal vitamin with a meal or before bed at night in order to sleep through the discomfort. If you still feels queasy from a vitamin, ask a health care provider about other options and she might recommend breaking up dosages throughout the day.

If you choose to supplement your diet with synthetic nutrients, be sure to keep track of the daily amounts you take, and let your healthcare provider know. It is possible to overdose on particular nutrient and combining supplements can raise concerns about consuming too much of one nutrient.

Taking more than the Recommended Daily Allowance of one nutrient should be avoided while pregnant. Iron, folic acid, and zinc are the most toxic in high levels and easiest to overdose. If you are taking a calcium supplement and consuming a lot of calcium-enriched foods, you could be consuming too much calcium. Fat-soluble vitamins, such as vitamin A and E can accumulate in the body, and also have a higher potential for toxicity, and should be monitored. Other vitamins like Vitamin D and B-vitamins are generally harder to reach levels of toxicity.[18]

Many experts recommend that women who are trying to conceive take folic acid supplements to get the necessary 400 to 800 micrograms (mcg) a day in order to prevent neural tube defects. However, women who aren’t pregnant, including women who are trying to conceive, should refrain from taking prenatals because the doses of vital nutrients, especially iron and folic acid, are above the recommended dose for a non-pregnant women, which may be harmful in the long-term. Rather than taking prenatals, there are preconception pills that include folic acid, and are targeted for women who are trying to conceive with appropriate dosages that have shown some promise in helping women conceive in a trial study.[19]

Recommended Products and Methodology

Prescription prenatal supplements are not necessarily higher quality or more complete than regular multivitamins. When choosing a prenatal supplement, you should try to find one that has a seal of approval from independent organizations, such as the United States Pharmacopeia (USP), NSF International, and Consumer Lab, which all use criteria to ensure the supplement meets high standards, and don’t contain lead, mercury, other heavy metals, pesticides, bacteria, molds, toxins and other potentially harmful contaminants. Our recommended supplements pass our rigorous methodology.

Some other considerations when choosing a supplement is that the vitamin contains the right type of vitamin A. While essential for fetal growth and development, vitamin A can come in two various forms, beta-carotene and retinol. Retinol has been shown to cause birth defects in large amounts and you should therefore find a prenatal supplement that contains beta-carotene instead.[20]

When choosing a supplement, you may also try to find one that retains more natural ingredients than synthetic. For example, natural vitamin E is better retained and more biologically active than the synthetic version.[21] True, Vitamin E is available in many different forms. In its natural form, vitamin E is designated d-, as in-d-alpha-tocopherol, while its synthetic forms are dl-, as in dl-alpha-tocopherol. On a supplement label, natural vitamin E is listed as d-alpha tocopherol, d-alpha tocopheryl acetate, or d-alpha tocopheryl succinate, while synthetic forms of vitamin E are labeled with a dl- prefix.

Which is the Best Prenatal Supplement?

Check out our unbiased recommendation of the best products on the market using our rigorous methodology. We screen products for the right formulation, bioavailability, safety, and efficacy to bring you only the best supplements available in 2019.

References:
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2 Greenberg JA, Bell SJ, Guan Y, Yu Y. (2011). Folic Acid Supplementation and Pregnancy: More Than Just Neural Tube Defect Prevention. Reviews in Obstetrics and Gynecology, 4(2), 52–59. Accessed through: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3218540/
3 Coffey-Vega K; Besa E. “Folic Acid Deficiency.” Medscape. July 2017. Accessed through: http://emedicine.medscape.com/article/200184-overview
4 Honein MA, Paulozzi LJ, Mathews TJ, Erickson JD, Wong LY. “Impact of folic acid fortification of the US food supply on the occurrence of neural tube defects.” JAMA. 2001 Jun 20. 285(23):2981-6. [Medline].
5 “Folate: Dietary Supplement Fact Sheet.” National Institutes for Health: Office of Dietary Supplements. Updated Apr 2016. Accessed through: https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/
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7 “Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline.” Washington (DC): National Academies Press (US); 1998. 8, Folate. Available from: https://www.ncbi.nlm.nih.gov/books/NBK114318/ Accessed through: https://www.ncbi.nlm.nih.gov/books/NBK114318/#ch8.s80
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11 Mohamed S, Al-Hendy A, Schulkin J, Power ML, “Opinions and Practice of US-Based Obstetrician-Gynecologists regarding Vitamin D Screening and Supplementation of Pregnant Women,” Journal of Pregnancy, vol. 2016, Article ID 1454707, 7 pages, 2016. doi:10.1155/2016/1454707 Accessed through: https://www.hindawi.com/journals/jp/2016/1454707/
12 Hollis BW, Johnson D, Hulsey TC, Ebeling M, Wagner CL. Vitamin D Supplementation during Pregnancy: Double Blind, Randomized Clinical Trial of Safety and Effectiveness. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. 2011;26(10):2341-2357. doi:10.1002/jbmr.463. Accessed through: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3183324/
13 Mithal A, Kalra S. “Vitamin D supplementation in pregnancy.” Indian Journal of Endocrinology and Metabolism. 2014;18(5):593-596. doi:10.4103/2230-8210.139204. Accessed through: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4171878/
14 Greenberg JA, Bell SJ, Ausdal WV. “Omega-3 Fatty Acid Supplementation During Pregnancy. Reviews in Obstetrics and Gynecology.” 2008;1(4):162-169.
Accessed through: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2621042/
15 Makrides M, Crosby DD, Bain E, Crowther CA. “Magnesium supplementation in pregnancy (Review)” The Cochrane Library. 2014, Issue 4. Accessed through: https://www.adelaide.edu.au/arch/research/publications/Makrides2014Magnesiumsupplementation.pdf
16 https://healthanchor.com/magnesium-supplement
17 Darnton-Hill, I. “Zinc supplementation during pregnancy: Biological, behavioural and contextual rationale.” e-Library of Evidence for Nutrition Actions (eLENA). World Health Organization. Jul 2013. Accessed through: http://www.who.int/elena/bbc/zinc_pregnancy/en/
18 Rosenbloom, M et al. “Vitamin Toxicity.” Medscape. Dec 2016. Accessed through: http://emedicine.medscape.com/article/819426-overview#showall
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20 “Fetal Retinoid Syndrome.” National Organization for Rare Disorders. Accessed through: https://rarediseases.org/rare-diseases/fetal-retinoid-syndrome/
21 “Vitamin E: Fact Sheet for Health Professionals.” National Institutes for Health: Office of Dietary Supplements. Updated Nov 2016. Accessed through: https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional/