Most women who are expecting take nutrition and wellness seriously for good reason, and as part of that, discover the importance of prenatal vitamins. A study published in the American Journal of Epidemiology in 2009 found that 95% of pregnant women surveyed were taking vitamins to support a healthy pregnancy. This study also found significantly lower rates of miscarriages for women who take vitamins during pregnancy (1) Below we examine some of the ingredients commonly found in prenatal vitamins and how they support pregnancy.

Folic Acid

This B-vitamin is the most well-researched nutrient for pregnant women. Consuming folic acid has been shown to prevent neural tube defects, or birth defects of the brain, spine, or spinal cord. In 1999, the American Academy of Pediatrics recommended that all women capable of becoming pregnant should consume 400mcg of folic acid per day in order to prevent neural tube defects. They believe that supplementing with 400mcg of folic acid per day could prevent approximately 50% of neural tube defects (3). A separate study in the Journal of the American Medical Association (JAMA) found a 72% reduction in neural tube defects among mothers who supplemented with folic acid (4). In 2010, a meta-analysis published in the International Journal of Epidemiology suggests folic acid can reduce neural tube defects by 46%. (20).

The FDA noted these results in an April 2015 statement: “The available data show that diets adequate in folate may reduce the risk of neural tube defects. The strongest evidence for this relationship comes from an intervention study by the Medical Research Council of the United Kingdom that showed that women at risk of recurrence of a neural tube defect pregnancy who consumed a supplement containing 4 milligrams (4,000 micrograms (mcg)) folic acid daily before conception and continuing into early pregnancy had a reduced risk of having a child with a neural tube defect” (2). It should be noted that folic acid supplementation is recommended both for pregnant women and women seeking to become pregnant.

Vitamin B12

Recent studies have shown that B12 deficiency during pregnancy has become more prevalent as folic acid intake has increased (6). A study in India found that babies born with high folic acid and low vitamin B12 were more likely to have higher adiposity and insulin resistance (5). B12 is often poorly digested and vegetarians are at high risk of B12 deficiency. A review study published in 2014 in Nutrition Reviews claims that B12 deficiency in infants can cause: “irritability, failure to thrive, apathy, anorexia and developmental regression”(7).

Vitamin C

A randomized, double-blind placebo controlled study published in 2005 suggests vitamin C supplementation during pregnancy reduces the risk of PROM (premature rupture of the chorioamniotic membranes) (8). The FDA has set a recommended daily intake of 120 mg per day of vitamin C for pregnant and lactating women, compared to 90mg for men and non-pregnant females.

Vitamin D

A 2009 study published in The Journal of Clinical Endocrinology and Metabolism found that women who were deficient in vitamin D were almost four times more likely to need a caesarean section (9). Another study published in 2007 found that women who had preeclampsia were twice as likely to be deficient in vitamin D (10).

Choline

Choline is a water-soluble vitamin that humans produce in the liver and can get from several food sources including milk, brown rice, and certain nuts and vegetables. A study published in the American Journal of Epidemiology found that women in the highest percentile of dietary choline intake had significantly less risk of neural tube defects when compared to pregnant women who were in the bottom 25th percent of dietary choline intake (11). A review article published in The Journal of Pediatrics in 2006 concludes that choline is needed for brain hippocampal development and normal neural tube closure (12).

Vitamin E

A study published in the American Journal of Respiratory and Critical Care Medicine suggests that women with higher rates of vitamin E during pregnancy produce children with lower rates of asthma symptoms (13).

Vitamin A

Vitamin A is important for lung development, especially in the second and third trimester (14). A study published in 1984 in the American Journal of Clinical Nutrition states that “mothers of premature infants had lower levels of serum vitamin A than those of full-term infants suggesting maternal vitamin A status to be one of the correlates of prematurity. Significant correlations were found between cord serum vitamin A, maternal serum vitamin A, gestational age, and growth status” (15).

Zinc

Zinc deficiency can lead to poor fetal growth and low birth weight. A study published in the Journal of American Medicine in 1995 studied 580 low-income women with low serum zinc concentrations. These women were given 25mg per day of zinc or a placebo. The group supplementing with zinc had a 37% reduction in the number of babies born with very low birth weight (16).

Selenium

A study published in The American Journal of Obstetrics and Gynecology found that women in the UK who experienced preeclampsia had lower selenium levels than a sample of women who did not experience preeclampsia (18).

Iron

According to a CDC report from 1998, “iron deficiency is the most common known form of nutritional deficiency. Its prevalence is highest among young children and women of childbearing age (particularly pregnant women). In children, iron deficiency causes developmental delays and behavioral disturbances, and in pregnant women, it increases the risk for a preterm delivery and delivering a low-birthweight baby” (19). In the same report, the CDC recommends a low-dose iron supplement for all pregnant women. The CDC report also states that “among pregnant women, iron deficiency anemia during the first two trimesters of pregnancy is associated with a twofold increased risk for preterm delivery and a threefold increased risk for delivering a low birth weight baby . Evidence from randomized control trials indicates that iron supplementation decreases the incidence of iron deficiency anemia during pregnancy, but trials of the effect of universal iron supplementation during pregnancy on adverse maternal and infant outcomes are inconclusive” (19).

Fish Oil

The FDA recommends that pregnant women consume 2-3 servings of fish per week. A fish oil supplement can be a good substitution if you do not eat fish (21).

Calcium

Calcium has been shown to be beneficial for gestational hypertension. A double-blind, placebo-controlled study was performed on 189 pregnant subjects from 20-weeks’ gestation until delivery. The rate of pregnancy-induced hypertension was 8.24% in the calcium group and 29.03% in the placebo group. The incidence of gestational hypertension was 6.18% in the calcium group and 17.20% in the placebo group. The rate of preeclampsia was also lower for the calcium group, at 2.06%, compared to 11.82% in the placebo group.

A 1999 clinical trial on 456 pregnant Australian women also examined the effect of calcium on gestational hypertension. This study concluded that calcium reduced the risk of preeclampsia and preterm birth, but did not decrease the frequency of pregnancy-induced hypertension.

In 2010, a meta-analysis reviewed 13 high quality studies involving a total of 15,730 pregnant women. Twelve of the 13 studies, including 15,470 subjects, suggest that calcium supplementation reduces the risk of hypertension during pregnancy. The analysis also concluded that calcium reduces the risk of preterm birth. Most of the women in the trials were low-risk for preterm birth and had a low calcium diet.

Coenzyme Q10

197 pregnant women with high-risk of preeclampsia were enrolled in a randomized, double-blind, placebo-controlled trial. They were designated to receive 200mg of CoQ10 or a placebo daily from 20 weeks of pregnancy until delivery. 30 women in the placebo group experienced pre-eclampsia, compared to 17 in the CoQ10 group.

Magnesium

One of the functions of magnesium is regulating blood pressure. A common problem that women experience during pregnancy is gestational hypertension, or high blood pressure. 61 pregnant women were enrolled in a double-blind, placebo-controlled study to assess the effect of magnesium on gestational hypertension. After 12 weeks of supplementation, the average diastolic blood pressure and incidence of hypertension was significantly lower in the group receiving magnesium. Higher urinary magnesium levels were associated with lower blood pressure during the study.