What are prenatal supplements?
Prenatal supplements, also known as prenatal vitamins, are supplements commonly taken by women during the pre-conception period and throughout pregnancy to ensure that both the mother and the fetus receive the appropriate amount of essential nutrients. Despite being referred to as “prenatal vitamins”, they typically include a combination of 3 or more vitamins and minerals. These may encompass vitamins B1, B2, B3, B6, B12, C, D, E, and K, along with folic acid, iodine, magnesium, iron, copper, zinc, selenium, and sometimes additional components like omega-3.[3][4]
It is generally recommended for all pregnant women to take at least iron and folic acid to support proper fetal development, and to prevent anemia and other complications during pregnancy. However, especially in low- and middle-income countries, women may experience multiple micronutrient deficiencies, and thus a prenatal multi-micronutrient supplement might be more suitable.[5]
What are the main benefits of prenatal supplements?
During pregnancy, when nutritional requirements are higher, micronutrient deficiencies can have adverse health and development consequences (e.g., preterm birth, small for gestational age, low birth weight). In many countries, it is recommended that women take prenatal supplements during pregnancy, typically containing a combination of iron and folic acid plus other vitamins and minerals.[4]
One meta-analysis, which included women of different gestational ages in low-income and middle-income countries, revealed that supplementation with a multiple-micronutrient (MMN) supplement (i.e., one containing 3 or more micronutrients) reduced the risk of low birth weight infants and the risk of babies considered small for gestational age more than supplementation with just iron and folic acid (IFA); this effect was especially pronounced with supplements containing more than 4 micronutrients. MMN supplementation also lowered the risk of stillbirth and the occurrence of diarrhea in children. Moreover, MMN slightly increased maternal and child serum retinol levels, slightly increased maternal zinc and vitamin B12 levels, and improved executive function scores in children, compared to IFA. However, no difference was noted for all other studied outcomes, including maternal or perinatal mortality, risk of miscarriage, risk of congenital anomalies, preterm births, risk of C-section, child general intelligence, motor functioning, verbal comprehension, or language.[4] While studies such as this one suggest benefits from taking an MMN prenatal supplement instead of one that only contains folic acid and iron, variations in methods and interventions used, such as supplement composition, may need to be addressed before drawing generalized conclusions.
Whether MMN supplements are more beneficial than just IFA in upper-middle-income and high-income countries remains unclear: it likely varies depending on the intake of essential micronutrients from the diet.[6]
What are the main drawbacks of prenatal supplements?
Prenatal supplements are generally considered safe and well-tolerated when taken at the recommended dosage. However, it’s important not to exceed the recommended daily intake during pregnancy, as higher doses of certain vitamins and minerals may be harmful to the fetus (e.g., iron, folic acid, zinc). Studies specifically addressing the risks of exceeding the upper limit (UL) of these micronutrients during pregnancy are lacking, except for vitamin A. Excessive intake of vitamin A (above 3000 μg)[7] during pregnancy is known to have teratogenic (i.e., birth-defect-causing) effects.[1][2] In some prenatal supplements, vitamin A is substituted with beta-carotene, which is converted into vitamin A naturally by the body as required and does not appear to be teratogenic at high doses.[8]
Another potential side effect of taking prenatal vitamins and minerals is constipation, primarily caused by iron.[9]
How do prenatal supplements work?
Prenatal supplements contain a blend of different vitamins, minerals, and other nutrients, all of which are known to play a crucial role in various biological reactions and metabolic activities, thereby promoting maternal health and supporting fetal growth. Therefore, there is more than one mechanism of action involved, depending on the micronutrient composition of each supplement. For detailed information on how each micronutrient functions in the body, please refer to the individual pages dedicated to those specific nutrients.
What are other names for Prenatal Vitamins
- Maternity vitamins
- Pregnancy supplements
- Antenatal vitamins
- Prenatal vitamins
- Prenatal multivitamins
- Gestational vitamins
- Preconception vitamins
- Maternal health supplements
- Prenatal minerals and nutrients
- Multiple-micronutrient supplements
Dosage information
The dosage of prenatal supplements can vary by brand, so it’s advisable to refer to the instructions provided on the manufacturer’s website or supplement package.
During pregnancy, it’s important to avoid exceeding the recommended dosage. Consuming certain vitamins and minerals in excess amounts may pose risks to the fetus.[1][2]
Frequently asked questions
Prenatal supplements, also known as prenatal vitamins, are supplements commonly taken by women during the pre-conception period and throughout pregnancy to ensure that both the mother and the fetus receive the appropriate amount of essential nutrients. Despite being referred to as “prenatal vitamins”, they typically include a combination of 3 or more vitamins and minerals. These may encompass vitamins B1, B2, B3, B6, B12, C, D, E, and K, along with folic acid, iodine, magnesium, iron, copper, zinc, selenium, and sometimes additional components like omega-3.[3][4]
It is generally recommended for all pregnant women to take at least iron and folic acid to support proper fetal development, and to prevent anemia and other complications during pregnancy. However, especially in low- and middle-income countries, women may experience multiple micronutrient deficiencies, and thus a prenatal multi-micronutrient supplement might be more suitable.[5]
Micronutrient deficiencies during pregnancy can have significant consequences on both the mother and the baby. Here are some of the most common deficiencies and their associated risks:
Iron deficiency during pregnancy is among the most common nutrient deficiencies. Low iron levels can lead to iron deficiency anemia (IDA) which can have negative consequences both on the mother and the baby.[4]
Low folate levels are associated with infant neural tube defects.[4]
Severe iodine deficiency can cause irreversible neurological damage to the fetus, resulting in congenital hypothyroidism, which, if not treated within a month of birth, can result in permanent intellectual disability.[10][11] Iodine deficiency is rare in most countries, as in the majority of countries most people get enough iodine from food; however, sub-Saharan Africa and South Asia still have relatively high incidences of iodine deficiency.[12]
Calcium and vitamin D deficiencies during pregnancy are associated with hypertension (high blood pressure) and increased risk of preeclampsia (a pregnancy complication characterized by high blood pressure), as well as high levels of protein in the urine, all of which can have negative consequences for both the mother and the fetus.[13][4][14]
Selenium deficiency has been associated with poor pregnancy outcomes, including increased incidences of recurrent miscarriage, preeclampsia, intrauterine growth restriction, and preterm birth.[15]
Although there are clear recommended dietary allowances (RDA) for total vitamin intake from both food and supplements, the composition of prenatal vitamin supplements on the market can vary. The following table presents recommendations for the optimal level of prenatal vitamin supplementation for pregnant women in the United States, based on a literature review.PMC: 9275129[7]
| Nutrient | Daily recommendation | Tolerable UL for pregnant women |
|---|---|---|
| Vitamin A | 1200 μg of preformed vitamin A & 1000 μg as mixed carotenoids | 3000 μg |
| Vitamin C | 200 mg | 2000 mg |
| Vitamin D | 2000 IU | 4000 IU |
| Vitamin E | 19 mg | 1000 mg |
| Vitamin K | 90 μg | |
| DHA | 600 μg | |
| Vitamin B1 (Thiamine) | 6 mg | - |
| Vitamin B2 (Riboflavin) | 2 mg | - |
| Vitamin B3 (Niacin) | 35 mg | - |
| Vitamin B5 (Pantothenic acid) | 10 mg | - |
| Vitamin B6 (Pyridoxine) | 10 mg | 100 mg |
| biotin Vitamin B7 (Biotin) | 100 μg | - |
| Vitamin B9 (Folate) | 400 μg | 1000 μg |
| Vitamin B12 | 25 μg | - |
| Choline | 350 mg (1st and 2nd trimester), 600 mg (3rd trimester) | 3500 mg/day |
| Inositol | 500 mg | - |
As with vitamins, there are clear RDAs for total mineral intake from both food and supplements, but the mineral content of prenatal supplements can vary. The following table presents recommendations for the optimal level of prenatal mineral supplementation for pregnant women in the United States, based on a literature review.[16]
| Nutrient | Daily recommendation | Tolerable UL for pregnant women |
|---|---|---|
| Calcium | 550 mg (1000 mg for those with greater risk of preeclampsia) | 1000 mg |
| Chromium | 100 mg (200 mg for women with diabetes) | - |
| Copper | 100 mg (200 mg for women with diabetes) | 10 mg |
| Iodine | 150 μg/day | 1100 μg |
| Iron | 30 mg 1st trimester, 60 mg 2nd trimester and 3rd trimester; up to 60 mg 3× day in extreme cases | 45 mg |
| Magnesium | 350 mg | 400 mg |
| Manganese | 1 mg | 11 mg |
| Molybdenum | 25 μg | 2000 μg |
| Selenium | 60 μg | 400 mg |
| Zinc | 30 μg | 40 mg |
During pregnancy, when nutritional requirements are higher, micronutrient deficiencies can have adverse health and development consequences (e.g., preterm birth, small for gestational age, low birth weight). In many countries, it is recommended that women take prenatal supplements during pregnancy, typically containing a combination of iron and folic acid plus other vitamins and minerals.[4]
One meta-analysis, which included women of different gestational ages in low-income and middle-income countries, revealed that supplementation with a multiple-micronutrient (MMN) supplement (i.e., one containing 3 or more micronutrients) reduced the risk of low birth weight infants and the risk of babies considered small for gestational age more than supplementation with just iron and folic acid (IFA); this effect was especially pronounced with supplements containing more than 4 micronutrients. MMN supplementation also lowered the risk of stillbirth and the occurrence of diarrhea in children. Moreover, MMN slightly increased maternal and child serum retinol levels, slightly increased maternal zinc and vitamin B12 levels, and improved executive function scores in children, compared to IFA. However, no difference was noted for all other studied outcomes, including maternal or perinatal mortality, risk of miscarriage, risk of congenital anomalies, preterm births, risk of C-section, child general intelligence, motor functioning, verbal comprehension, or language.[4] While studies such as this one suggest benefits from taking an MMN prenatal supplement instead of one that only contains folic acid and iron, variations in methods and interventions used, such as supplement composition, may need to be addressed before drawing generalized conclusions.
Whether MMN supplements are more beneficial than just IFA in upper-middle-income and high-income countries remains unclear: it likely varies depending on the intake of essential micronutrients from the diet.[6]
Prenatal supplements are generally considered safe and well-tolerated when taken at the recommended dosage. However, it’s important not to exceed the recommended daily intake during pregnancy, as higher doses of certain vitamins and minerals may be harmful to the fetus (e.g., iron, folic acid, zinc). Studies specifically addressing the risks of exceeding the upper limit (UL) of these micronutrients during pregnancy are lacking, except for vitamin A. Excessive intake of vitamin A (above 3000 μg)[7] during pregnancy is known to have teratogenic (i.e., birth-defect-causing) effects.[1][2] In some prenatal supplements, vitamin A is substituted with beta-carotene, which is converted into vitamin A naturally by the body as required and does not appear to be teratogenic at high doses.[8]
Another potential side effect of taking prenatal vitamins and minerals is constipation, primarily caused by iron.[9]
Prenatal supplements contain a blend of different vitamins, minerals, and other nutrients, all of which are known to play a crucial role in various biological reactions and metabolic activities, thereby promoting maternal health and supporting fetal growth. Therefore, there is more than one mechanism of action involved, depending on the micronutrient composition of each supplement. For detailed information on how each micronutrient functions in the body, please refer to the individual pages dedicated to those specific nutrients.
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