While the report did not refute that deficiency in key nutrients has been linked to various complications during pregnancy and birth, including preeclampsia, restricted fetal growth, neural tube defects, skeletal deformities and low birth weight, dtb proposed that multivitamins and mineral supplements designed for pregnancy often include an excess of unneeded ingredients. According to the report, such products typically contain 20+ vitamins and minerals, including vitamins B1, B2, B3, B6, B12, C, D, E, K, folic acid, iodine, magnesium, iron, copper, zinc and selenium.
In an attempt to examine the current U.K. guidance for vitamin supplements recommended for pregnant women, dtb reviewed the published research on folic acid, vitamin D, iron, vitamins C, E, and A and multivitamin supplements.
It found that folic acid had the strongest evidence to support national U.K. guidance, which recommends that women take 400 ug of folic acid daily from before conception, until 12 weeks of pregnancy. A daily dose of 5 mg is recommended for those women at higher risk of having a child with neural tube defects, including those who have neural tube defects themselves, a family history of the condition, or those with diabetes.
The evidence for vitamin D supplementation was less clear-cut, according to the report, with little of the reviewed trial data showing any impact on reducing the risk of complications of pregnancy or birth. Nevertheless, a daily dose of 10 ug is recommended throughout pregnancy and breastfeeding.
The publication concluded there was no evidence of any obvious clinical benefit for most women who are well nourished, and high doses of vitamin A may harm the developing fetus. Additionally, the available data didn’t support the use of multivitamin supplements in most pregnant women.
“We found no evidence to recommend that all pregnant women should take prenatal multi-nutrient supplements beyond the nationally advised folic acid and vitamin D supplements, generic versions of which can be purchased relatively inexpensively,” the report stated.
Furthermore, dtb pointed out that a large portion of the research from which marketing claims for prenatal supplements are derived are conducted in low income countries, where women are more likely to be undernourished or malnourished, compared to women in the U.K. The report also said a good deal of the evidence was derived from observational studies, which are subject to bias and can only establish an association, not cause.
“For most women who are planning to become pregnant or who are pregnant, complex multivitamin and mineral preparations promoted for use during pregnancy are unlikely to be needed and are an unnecessary expense,” dtb concluded.
“The marketing of such products does not appear to be supported by evidence of improvement in child or maternal outcomes,” it added, suggesting that, “Pregnant women may be vulnerable to messages about giving their baby the best start in life, regardless of cost.”
In a statement discussing dtb’s report, Duffy MacKay, N.D., senior vice president, scientific and regulatory affairs, for The Council for Responsible Nutrition (CRN), defended the use of prenatal supplements for pregnant women.
“Reputable medical organizations, including the American Academy of Pediatrics, the Endocrine Society, and the American Thyroid Association, recommend that pregnant women take a multivitamin as a way to assure they are getting adequate nutrients such as folic acid and iodine that are critical for the development and well-being of the fetus, as well as for their own health. In fact, iodine is now recognized as a nutrient so critical to the cognitive development of the baby during pregnancy that CRN recently developed guidelines urging the dietary supplement industry to ensure that prenatal multivitamins contain at least 150 mcg of iodine daily,” he said.
Dr. MacKay stressed that good nutrition during pregnancy is important for healthy babies and mothers, and that pregnancy and breastfeeding are the only times when what a woman eats directly impacts another life. “The scientific evidence is clear—requirements for folic acid, calcium, iron, iodine, protein, and other nutrients go up during pregnancy—and the consequences of not getting enough can be significant for both mother and child,” he said. “In addition, we know from the 2015-2020 Dietary Guidelines that most Americans fall short in key nutrients, and pregnancy is no exception, especially if you consider appetite changes and nausea that can accompany pregnancy.”
While Dr. MacKay noted the authors dismay from the lack of more clinical evidence in support of supplement usage during pregnancy, he pointed to ethical issues with depriving women from essential nutrients for the sake of science. “It is unfortunate that, in addition to disregarding the immense value a multivitamin and its ingredients can provide pregnant women, the authors fail to acknowledge that conducting randomized controlled trials (RCTs) on a multivitamin in pregnant women would be unethical as you cannot deprive a pregnant woman of essential nutrients. When the totality of all available evidence is considered, the value of nutrient supplementation during pregnancy makes a clear case.”
Looking at the U.S., he said it’s clear that Americans are not getting the nutrition they need from food alone, which is why supplementation during pregnancy is so essential. “While it’s ideal to strive to get the Recommended Daily Allowance (RDA) of key nutrients from diet only, realistically, there will be shortfalls and dietary supplements fill those gaps. Pregnancy is no time to gamble. The alarming headlines that issued after this report published could lead to serious repercussions. We hope that other health organizations and healthcare practitioners will step up and speak out against the irresponsible nature of this report in order to protect the health of our pregnant population. ”