Pregnancy can be one of the most exciting and happy experiences in a woman’s life.

However, it can also be a confusing and overwhelming time for some mothers-to-be.

The internet, magazines and advertisements flood women with advice on how to stay healthy during pregnancy.

While most women know that high-mercury seafood, alcohol and cigarettes are off-limits during pregnancy, many are unaware that some vitamins, minerals and herbal supplements should be avoided as well.

Information on which supplements are safe and which aren’t often varies between sources, making things more complicated.

This article breaks down which supplements are believed to be safe to take during pregnancy and explains why some supplements must be avoided.

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Consuming the right nutrients is important at every stage of life, but it’s especially critical during pregnancy, as pregnant women need to nourish both themselves and their growing babies.

Pregnancy Increases the Need for Nutrients

During pregnancy, a woman’s macronutrient intake needs grow significantly. Macronutrients include carbohydrates, proteins and fats.

For example, protein intake needs to increase from the recommended 0.36 grams per pound (0.8 grams per kg) of body weight for non-pregnant women to 0.5 grams per pound (1.1 grams per kg) of body weight for pregnant women (1).

However, the requirement for micronutrients, which include vitamins, minerals and trace elements, increases even more than the need for macronutrients.

Vitamins and minerals support maternal and fetal growth at every stage of pregnancy and are required to support critical functions like cell growth and cell signaling (2).

While some women are able to meet this growing demand through a well-planned, nutrient-dense diet, others are not.

Some pregnant women may need to take vitamin and mineral supplements for various reasons, including:

  • Nutrient deficiencies: Some women may need a supplement after a blood test reveals a deficiency in a vitamin or mineral. Correcting deficiencies is critical, as a shortage of nutrients like folate has been linked to birth defects (3).
  • Hyperemesis gravidarum: This pregnancy complication is characterized by severe nausea and vomiting. It can lead to weight loss and nutrient deficiencies (4).
  • Dietary restrictions: Women who follow specific diets, including vegans and those with food intolerances and allergies, may need to supplement with vitamins and minerals to prevent micronutrient deficiencies (5, 6).
  • Smoking: Although it is absolutely critical for mothers to avoid cigarettes during pregnancy, those who continue to smoke have an increased need for specific nutrients like vitamin C and folate (7).
  • Multiple pregnancies: Women carrying more than one baby have higher needs for micronutrients than women carrying one baby. Supplementing is often necessary to ensure optimal nutrition for both the mother and her babies.
  • Genetic mutations like MTHFR: MTHFR is a gene that converts folate into a form that the body can use. Pregnant women with this gene mutation may need to supplement with a specific form of folate to avoid complications (8).
  • Poor diet: Women who undereat or choose foods low in nutrients may need to supplement with vitamins and minerals to avoid deficiencies.

In addition, experts like those at the American Congress of Obstetrics and Gynecology recommend that all pregnant women take a prenatal vitamin and folic acid supplement. This is advised to fill in nutritional gaps and prevent birth defects like spina bifida (9).

For these reasons, many moms-to-be turn to vitamin and mineral supplements.

Herbal Supplements During Pregnancy

In addition to micronutrients, herbal supplements are popular.

One study found that around 15.4% of pregnant women in the US use herbal supplements.

Alarmingly, over 25% of these women didn’t inform their doctor they were taking them (10).

While some herbal supplements may be safe to take during pregnancy, there are far more that might not be.

Although some herbs can help with common pregnancy complications like nausea and upset stomach, some may be harmful to both the mother and fetus (11).

Unfortunately, there isn’t much research regarding the use of herbal supplements by pregnant women and much is unknown about how the supplements can affect expectant mothers.

Summary Pregnant women turn to micronutrient and herbal supplements for various reasons. While some are safe and helpful, others can lead to serious complications that can be harmful to both the mother and baby.

Just like medications, all micronutrient and herbal supplements should be approved and supervised by your doctor to ensure that they are necessary and taken in safe amounts.

Always purchase vitamins from a reputable brand that volunteers to have their products evaluated by third-party organizations like the United States Pharmacopeial Convention (USP).

This ensures that the vitamins live up to quality standards and are generally safe to take.

1. Prenatal Vitamins

Prenatal vitamins are multivitamins that are specially formulated to meet the increased demand for micronutrients during pregnancy.

They are intended to be taken before conception and during pregnancy and lactation.

Observational studies have shown that supplementing with prenatal vitamins reduces the risk of preterm birth and preeclampsia. Preeclampsia is a potentially dangerous complication characterized by high blood pressure and possibly protein in the urine (12, 13).

While prenatal vitamins are not meant to replace a healthy diet, they may help prevent nutritional gaps by providing extra micronutrients that are in high demand during pregnancy.

Since prenatal vitamins contain the vitamins and minerals that pregnant women need, taking additional vitamin or mineral supplements may not be necessary unless suggested by your doctor.

Prenatal vitamins are often prescribed by doctors and also available over-the-counter.

2. Folate

Folate is a B vitamin that plays an integral role in DNA synthesis, red blood cell production and fetal growth and development (14).

Folic acid is the synthetic form of folate found in many supplements. It gets converted into the active form of folate, L-methylfolate, in the body.

It is recommended that pregnant women take 600 ug of folate or folic acid per day in order to reduce the risk of neural tube defects and congenital abnormalities like cleft palate and heart defects (15).

In a review of five randomized studies including 6,105 women, supplementing with folic acid daily was associated with a reduced risk of neural tube defects. No negative side effects were noted (16).

Although adequate folate can be obtained through diet, many women don’t eat enough folate-rich foods, making supplementation necessary (17).

Additionally, the Centers for Disease Control and Prevention recommend that all women of childbearing age consume at least 400 mg of folate or folic acid per day.

This is because many pregnancies are unplanned, and birth defects from a folate deficiency can occur very early in pregnancy, even before most women know they are pregnant.

It may be wise for pregnant women, especially those with an MTHFR genetic mutation, to choose a supplement that contains L-methylfolate to ensure maximum uptake (18).

3. Iron

The need for iron increases significantly during pregnancy, as maternal blood volume increases by nearly 50% (19).

Iron is critical for oxygen transport and healthy growth and development of the fetus and placenta.

The prevalence of iron deficiency in pregnant women in the US is around 18%, and 5% of these women are anemic (20).

Anemia during pregnancy has been associated with preterm delivery, maternal depression and infant anemia (21, 22).

The recommended intake of 27 mg iron per day can be met through most prenatal vitamins. However, pregnant women with iron deficiency or anemia need higher doses of iron, managed by their doctor.

Pregnant women that are not iron deficient should not take more than the recommended intake of iron to avoid adverse side effects. These may include constipation, vomiting and abnormally high hemoglobin levels (23).

4. Vitamin D

This fat-soluble vitamin is important for immune function, bone health and cell division.

Vitamin D deficiency during pregnancy has been linked to an increased risk of cesarean section, preeclampsia, preterm birth and gestational diabetes (24).

The current recommended intake of vitamin D during pregnancy is 600 IU per day. However, some experts suggest that vitamin D needs during pregnancy are much higher (25).

All pregnant women should speak with their doctor regarding screening for vitamin D deficiency and proper supplementation.

5. Magnesium

Magnesium is a mineral involved in hundreds of chemical reactions in your body. It plays critical roles in immune, muscle and nerve function (26).

Deficiency in this mineral during pregnancy may increase the risk of chronic hypertension and premature labor (27).

Some studies suggest that supplementing with magnesium may reduce the risk of complications like fetal growth restriction and preterm birth (28).

6. Ginger

Ginger root is commonly used as a spice and herbal supplement.

In supplement form, it’s most commonly used to treat nausea caused by motion sickness, pregnancy or chemotherapy.

A review of four studies suggested that ginger is both safe and effective for treating pregnancy-induced nausea and vomiting (29).

Nausea and vomiting are common during pregnancy, with up to 80% of women experiencing this in the first trimester of pregnancy (30).

Though ginger may help reduce this unpleasant pregnancy complication, more research is needed to identify the maximum safe dosage.

7. Fish Oil

Fish oil contains DHA and EPA, two essential fatty acids that are important for fetal brain development.

Supplementing with DHA and EPA in pregnancy might boost infant brain development and decrease maternal depression, though research on this topic is inconclusive.

Although observational studies have shown improved cognitive function in the children of women who supplemented with fish oil during pregnancy, several controlled studies have failed to show a consistent benefit.

For example, one study involving 2,399 women found no difference in the cognitive function of infants whose mothers had supplemented with fish oil capsules containing 800 mg of DHA per day during pregnancy, compared to infants whose mothers did not (31).

This study also found that supplementing with fish oil had no effect on maternal depression.

However, the study found that supplementing with fish oil protected against preterm delivery, and some evidence suggests that fish oil may benefit fetal eye development (32).

Maternal DHA levels are important for proper fetal development and supplementing is considered safe. The jury is still out on whether taking fish oil during pregnancy is necessary.

To get DHA and EPA through diet, pregnant women are encouraged to consume two to three servings of low-mercury fish like salmon, sardines or pollock per week.

8. Probiotics

With an increasing interest in gut health, many moms-to-be turn to probiotics.

Probiotics are living microorganisms that are thought to benefit digestive health.

Many studies have shown that probiotics are safe to take during pregnancy, and no harmful side effects have been identified, aside from an extremely low risk of probiotic-induced infection (33).

Additionally, several studies have shown that supplementing with probiotics may reduce the risk of gestational diabetes, postpartum depression and infant eczema and dermatitis (34, 35, 36, 37).

Research on probiotic use in pregnancy is ongoing, and more about the role of probiotics in maternal and fetal health is sure to be discovered.

Summary Supplements like folate, iron and prenatal vitamins are considered safe for pregnant women. It is important to always discuss any supplement, whether it is a vitamin, mineral or herb, with your doctor.

While supplementing with some micronutrients and herbs is safe for pregnant women, many should be avoided.

1. Vitamin A

Although this vitamin is extremely important for fetal vision development and immune function, too much vitamin A can be harmful.

Because vitamin A is fat-soluble, the body stores excess amounts in the liver.

This accumulation can have toxic effects on the body that can lead to liver damage. It can even cause birth defects in babies.

For example, excessive amounts of vitamin A during pregnancy has been shown to cause congenital birth defects (38).

Between prenatal vitamins and diet, pregnant women should be able to get enough vitamin A, and additional supplementation is not advised.

2. Vitamin E

This fat-soluble vitamin plays many important roles in the body and is involved in gene expression and immune function (39).

While vitamin E is very important for health, it’s recommended that pregnant women do not supplement with it.

Supplementing with vitamin E has not been shown to improve outcomes for either mothers or babies and may instead increase the risk of abdominal pain and premature rupture of the amniotic sack (40).

3. Black Cohosh

A member of the buttercup family, black cohosh is a plant used for a variety of purposes, including controlling hot flashes and menstrual cramps.

It is unsafe to take this herb during pregnancy, as it can cause uterine contractions, which could induce preterm labor (41).

Black cohosh has also been found to cause liver damage in some people (42).

4. Goldenseal

Goldenseal is a plant that is used as a dietary supplement to treat respiratory infections and diarrhea, although there is very little research on its effects and safety.

Goldenseal contains a substance called berberine, which has been shown to worsen jaundice in infants. It can lead to a condition called kernicterus, a rare type of brain damage that can be fatal (43).

For these reasons, pregnant women should avoid goldenseal.

5. Dong quai

Dong quai is a root that has been used for over 1,000 years and popular in Chinese Medicine.

Though used to treat everything from menstrual cramps to high blood pressure, evidence regarding its efficacy and safety is lacking.

Pregnant women should avoid dong quai because it may stimulate uterine contractions, raising the risk of potential miscarriage (44).

6. Yohimbe

Yohimbe is a supplement that is made from the bark of a tree native to Africa.

It’s used as an herbal remedy to treat a range of conditions from erectile dysfunction to obesity.

This herb should never be used during pregnancy, as it has been associated with dangerous side effects like high blood pressure, heart attacks and seizures (45).

7. Other Herbal Supplements Considered Unsafe During Pregnancy:

  • Saw palmetto
  • Tansy
  • Red clover
  • Angelica
  • Yarrow
  • Wormwood
  • Blue Cohosh
  • Pennyroyal
  • Ephedra
  • Mugwort
Summary Many vitamins and herbal substances should not be taken during pregnancy. Always consult your doctor before taking any micronutrient or herbal supplements.

Pregnancy is a time of growth and development, making health and nutrition a top priority.

While some supplements can be helpful during pregnancy, many can cause dangerous side effects in both pregnant women and their babies.

Importantly, while supplementing with certain vitamins and minerals may help fill nutritional gaps, supplements are not meant to replace a healthy diet and lifestyle.

Nourishing your body with nutrient-dense foods, as well as getting enough exercise and sleep and minimizing stress, is the best way to ensure a healthy pregnancy for you and your baby.

Although supplements can be necessary and helpful in certain circumstances, always check with your doctor regarding doses, safety and potential risks and benefits.