Prenatal Supplements: Amounts of Some Key Nutrients Differed from Product Labels

What GAO Found

GAO contracted with an accredited laboratory to test 12 prenatal supplements for amounts of certain nutrients. GAO found that 11 of the 12 of the prenatal supplement products had at least one tested nutrient (folic acid, iodine, iron, or vitamin A, C, or E) that, on average, contained an amount outside of acceptable deviations from the amount stated on the label. This could lead to a pregnant individual either consuming too much or too little of these nutrients. Of these 11, we found one product with an average amount of folic acid that may cause a health concern based on metrics established by the Institute of Medicine. The other tested products that deviated from the amounts stated on the labels did not contain average amounts of nutrients likely to be a health concern. Of the six nutrients tested, Vitamin E showed the greatest variability between different prenatal supplement products, with a range of 28 percent to 332 percent of the amount stated on the label. Vitamin A was the nutrient most frequently found in amounts outside the acceptable deviations from the label value (nine of the 12 supplements). For a full description of the results, see GAO-24-107042.

GAO also had the 12 prenatal supplements tested for certain heavy metal contaminants (arsenic, cadmium, lead, and mercury). GAO found trace amounts of two heavy metals—lead or cadmium—in half of the tested prenatal supplements (six of 12), but not in amounts likely to cause a health concern based on metrics used by the Food and Drug Administration (FDA).

Many pregnant Americans take prenatal supplements to promote parental and fetal health as soon as they recognize they are pregnant, according to experts with the American College of Obstetricians and Gynecologists. However, dietary supplements—including prenatal supplements—are not generally required to be registered with FDA or evaluated for safety or effectiveness before reaching the shelves. This is because FDA regulates dietary supplements as a special category of food and not as drugs, limiting pre-market oversight. As a result, FDA has limited information about the dietary supplements on the market—including prenatal supplements—to inform its post-market inspections and oversight. Moreover, there is no federal statutory definition of what a prenatal supplement is and what these products should contain, resulting in a large and highly variable product market.

Experts and stakeholders GAO spoke with identified a variety of challenges regarding dietary supplements and their oversight. Some concerns include a lack of standardization and limited market knowledge. Prior GAO work also found that FDA faces challenges related to limited information about the dietary supplement market. FDA and a dietary supplement trade association have publicly backed proposed legislation to increase FDA's oversight of dietary supplements, such as requiring dietary supplement manufacturers to register each product on the market with FDA. The stakeholders we interviewed also supported additional oversight of dietary supplements by FDA.

Why GAO Did This Study

GAO was asked to assess the accuracy of over-the-counter prenatal supplement labels for amounts of certain nutrients and determine whether the supplements contain harmful substances, such as heavy metals. This Q&A describes the accuracy of labels for the amounts of tested nutrients and possible heavy metal contaminants in 12 selected best-selling prenatal supplements. It also provides information on FDA's role overseeing prenatal supplements.

GAO contracted with an accredited analytical laboratory to conduct blind testing of three different lots of each of the 12 selected supplement products for six nutrients and four heavy metals. GAO selected the nutrients and contaminants for testing based on a review of the literature and information available online from expert organizations. The prenatal supplement products tested are a nongeneralizable sample selected from a list of "best-selling" or "top-rated" prenatal supplements from the websites of major retailers and compared to "best of" lists found online. To gain contextual information for the testing results, GAO interviewed selected stakeholders and experts—including third-party dietary supplement testing organizations and the American College of Obstetricians and Gynecologists, respectively. GAO also interviewed officials from relevant federal agencies—including FDA—and reviewed agency guidance and data, relevant legislation, and prior GAO reports to analyze FDA's oversight role for dietary supplements.