Pregnancy & Supplement Safety
Get enough of the ones you need, but steer clear of just about everything else
The body's folic acid need more than doubles during pregnancy.
During pregnancy and while breast-feeding women's nutritional needs change. Some supplements and herbs are unsafe to take during pregnancy, even if they are safe or necessary at other times. Always consult with your doctor if you are pregnant and you want to take a supplement or herb of any kind. A good rule of thumb is to avoid any supplements or herbs unless they are necessary.
Which vitamins and minerals do I need more of during pregnancy?
The Recommended Dietary Allowance (RDA) for many vitamins and minerals increases during pregnancy. The vitamins and minerals listed below are only selected examples of the many required by pregnant women. A high-quality prenatal multivitamin is a good way for many women to meet additional needs for vitamins and minerals. Pregnant women should consult with their doctor at the beginning of prenatal care to determine how best to meet their specific nutritional needs.
For more information on having a happy, healthy pregnancy see Pregnancy and Postpartum Support.
- Folic acid:The body's folic acid need more than doubles during pregnancy. Folic acid deficiencies during pregnancy have been linked to low birth weight and to an increased incidence of neural tube defects (such as spina bifida) in infants. Most healthcare professionals recommend that women of childbearing age supplement with 400 to 800 mcg per day. Folic acid should be taken even before a woman knows she is pregnant and throughout the entire pregnancy. Folic-acid supplementation is important prior to conception because it provides its protection in the first weeks of pregnancy before a woman knows she has conceived. Waiting to begin supplementation until after you know you are pregnant may increase the risk of birth defects. Most prenatal multivitamins contain sufficient folic acid.
- Iron: The need for iron increases during pregnancy. The highest risk for iron deficiency occurs in the last weeks of pregnancy. Healthy nonpregnant women should not supplement with iron unless they have an iron deficiency proven by a blood test. Many, but not all, pregnant women eventually require iron supplementation during pregnancy, usually around 45 mg per day. Pregnant women may help increase the birth weight of their babies by taking iron supplements before 20 weeks' gestation. Women should consult with their doctor to find out if iron supplementation is right for them.
- Vitamin B12:Deficiency of vitamin B12 can cause anemia and irreparable damage to the nervous system. Vegans (people who eat no animal products), including those who are pregnant, should take a daily vitamin B12 supplement. Low maternal vitamin B12 levels are more commonly seen in smokers and are associated with low birth weights and premature birth. The RDA of vitamin B12 for pregnant women is 2.6 mcg per day from all sources. Lactating women require 2.8 mcg per day.
- Vitamin B6: Women who have taken oral contraceptives during the months prior to pregnancy may be at increased risk of vitamin B6 deficiency. Vitamin B6 supplementation in the range of 10 to 25 mg three times per day has been reported to help relieve morning sickness.
- Iodine: Adequate iodine intake is needed for fetal development and maintaining pregnancy. A healthful diet that includes iodized salt should supply ample iodine, particularly if a prenatal multivitamin that contains iodine is taken. No additional supplementation should be necessary.
- Calcium: Calcium needs increase significantly during pregnancy. Low dietary intake of calcium is associated with increased risk of preeclampsia (a potentially serious complication involving high blood pressure and kidney problems). Most pregnant women should consume about 1,500 mg of calcium per day (total from food and supplements). Those at high risk for preeclampsia should consider taking up to 2,000 mg per day.
- Biotin: A deficiency of biotin (a B-complex vitamin) may occur in as many as 50% of pregnant women, and this deficiency may increase the risk of birth defects, according to one study. Taking 300 mcg per day can correct a biotin deficiency.
- Zinc: Women may become marginally zinc deficient during pregnancy, particularly if they are supplementing with greater than 30 mg per day of iron. Studies conflict as to whether zinc supplementation is effective or necessary in well-nourished pregnant women. Most prenatal multivitamins contain sufficient zinc to prevent a deficiency.
- Probiotics: Women who take supplemental Lactobacillus GG (a probiotic or “friendly” bacterium) during pregnancy and breast-feeding may help lower the risk of their child developing eczema, according to a one study. Not all probiotic supplements are equal, so particular attention should be given to obtaining a high-quality supplement of the right type.
- Vitamin C: Vitamin C requirements are increased in pregnancy. Women with low intakes of vitamin C before and during pregnancy have increased risk of preterm delivery and of preeclampsia compared with women taking higher amounts. The recommended amount is 500 to 1,000 mg per day.
What supplements should I avoid when I am pregnant?
Supplements to avoid or use with caution during pregnancy include:
- Vitamin A: Women who are or could become pregnant have been told by doctors to take less than 10,000 IU per day of vitamin A to avoid the risk of birth defects. Although the evidence on which this recommendation is based has been contradicted by at least two studies, extremely large amounts of vitamin A do cause birth defects in experimental animals. The safe level for vitamin A supplementation in pregnant women is not known. Therefore, women who are pregnant should talk with a doctor before supplementing with more than 10,000 IU of vitamin A per day. This recommendation does not apply to beta-carotene.
- Vitamin D: Pregnant women need 400 IU of vitamin D per day. They should not exceed 1,000 IU per day unless supervised by a doctor.
- Supplemental hormones: Hormones sold as dietary supplements should be avoided during pregnancy, including androstenedione, melatonin, DHEA, human growth hormone, progesterone, and others, unless prescribed by a doctor.
- Untested supplements: Most newer and specialty nutrients have not been proven safe for use during pregnancy and should be avoided.
What herbs should I avoid when I am pregnant?
Many herbs can be used safely in pregnancy and may even help with some pregnancy-related symptoms (for example, ginger tea or syrup may help with morning sickness, the nausea usually experienced in the first trimester). But because some have the potential for causing miscarriage or other problems, avoid the following herbs during pregnancy:
- Caffeine-containing herbal supplements: Many herbal formulas (especially those that are intended to promote weight loss) contain caffeine or its relatives. While population studies have not proven caffeine’s harm in pregnancy, some research does suggest that caffeine consumption can increase the likelihood of miscarriages and fetal-growth impairment. Until more is known, women should limit their consumption of caffeine during pregnancy.
- Herbs with known dangers: Among others, the following herbs have the potential to disrupt pregnancy when taken as supplements and must be avoided by pregnant women (this is not a complete list):
- Achillea millefolium (yarrow)
- Acorus calamus (sweet flag)
- Aletris farinosa (unicorn root)
- Allium sativum (garlic supplements; garlic in moderation as a food is acceptable)
- Allium cepa (onion) (eat in moderation)
- Aloe vera, Aloe barbadensis (aloe)
- Anemone pulsatilla (wind flower)
- Areca catechu (betel)
- Aristolochia spp. (Virginia snakeroot, birthwort)
- Arnica montana (arnica)
- Artemisia absinthium (wormwood, absinthe)
- Asclepias tuberosa (pleurisy root)
- Berberis vulgaris (barberry)
- Brayera anthelmintica (kousso)
- Coffea arabica (coffee)
- Capsicum frutescens (cayenne)
- Caulophyllum thalictroides (blue cohosh)
- Cephaelis ipecacuanha (ipecac)
- Chelidonium majus (greater celandine)
- Chenopodium ambrosioides (wormseed)
- Cimicifuga racemosa (black cohosh)
- Cinchona officinalis (quinine)
- Cinnamomum zeylanicum (cinnamon)
- Citrullus colocynthis (bitter apple)
- Colchicum autumnale (autumn crocus)
- Conium maculatum (poison hemlock)
- Croton tiglium and other species (croton seed)
- Cytisus scoparius (broom, Scotch broom)
- Dryopteris spp. (fern)
- Ephedra sinica (Chinese ephedra)
- Foeniculum vulgare (fennel)
- Gelsemium sempervirens (yellow jessamine)
- Glycyrrhiza glabra (licorice)
- Hedeoma pulegioides (American false pennyroyal)
- Helleborus niger (Christmas rose)
- Hydrastis canadensis (goldenseal)
- Juniperus communis (juniper)
- Lavendula officinalis (lavender)
- Linum usitatissimum (flaxseeds; flaxseed oil is acceptable)
- Mentha pulegium (pennyroyal)
- Myristica fragrans (nutmeg)
- Nicotiana tabacum (tobacco)
- Papaver somniferum (opium poppy)
- Passiflora incarnata (passionflower)
- Petroselinum sativum (parsley supplements; parsley as a garnish is acceptable)
- Phytolacca americana (pokeweed)
- Pilocarpus jaborandi (jaborandi)
- Pinus palustris (southern pine; longleaf pine)
- Podophyllum peltatum (may apple)
- Polygala senega (Seneca snakeroot)
- Prunus persica (peach pit)
- Prunus serotina (wild black cherry pit)
- Prunus virginiana (chokecherry)
- Ranunculus spp. (buttercup)
- Rauwolfia serpentina (Indian snakeroot)
- Rheum spp. (rhubarb)
- Ricinus communis (castor bean, castor oil)
- Ruta graveolens (rue)
- Salvia officinalis (sage)
- Sanguinaria canadensis (bloodroot)
- Sassafrass albidum (sassafrass)
- Senecio vulgaris (groundsel)
- Strophanthus spp. (kombe seed)
- Strychnos nux-vomica (nux vomica)
- Tanacetum vulgare (tansy)
- Thuja occidentalis (American arborvitae, northern white cedar)
- Thymus vulgaris (thyme)
- Thymus serpyllum (lemon thyme)
- Veratrum spp. (false hellebore)
- Veronicastrum virginicum (Culver’s root)
- Vinca rosea (periwinkle)
- Viscum album (mistletoe)
Jeremy Appleton, ND, CNS, is a licensed naturopathic physician and certified nutrition specialist. He has worked extensively in scientific affairs in the dietary supplement industry and has taught nutrition at the National College of Naturopathic Medicine. Dr. Appleton is the co-author of MSM: The Definitive Guide. He is the former senior science editor for Healthnotes and is a frequent Healthnotes contributor.