Existing Nutritional Guidelines For Pregnant People Are Subpar, Study Finds

Historically, women and pregnant people have been left out of much of the scientific research guiding today's health recommendations, medicinal developments, and technological advances.

Now, a new study review suggests that pregnant people are specifically highly underrepresented in the scientific research that informs nutritional guidelines in the United States and Canada’s Dietary Reference Intakes, also known as DRIs. These guidelines are established to regulate everything from federal food programs to what goes into the processed items on your shelves.

Although this gap in data has likely skewed our understanding of how slices of the population can live healthier lives, tackling it as soon as possible can help increase representation and improve scientific research in the field of nutrition.

“It's not correct to think that excluding people from research protects them," Emily R. Smith, ScD, MPH, lead study author and assistant professor in the departments of global health and exercise and nutrition sciences at George Washington University, tells Verywell. "That means excluding them from information to help people live happy and healthy lives and have a positive pregnancy experience."

The research was published in October in the journal Science Advances.

Inclusive Research Is Important

This study spurred from Smith’s background in researching micronutrient supplementation for pregnant women. Her previous work looks at which and how many prenatal vitamins should be suggested to improve the health of moms and babies.

In her research, she found that even after women took these prenatal vitamins they sometimes still remained deficient at the end of pregnancy. 

“Although there are a number of issues that could affect the measurement of biomarkers in pregnancy, we wondered, well, how confident are we about the dosing that we say with the recommended daily allowance?" Smith says. "How competent are we about that? And how competent are we that we're measuring the right thing?”

To answer this question, Smith and her team analyzed 704 studies—looking at information about 23 micronutrients.

They found that 23% percent of the research included only male participants. In the research that did also include female participants, they were still underrepresented and only accounted for 29% of the participants. The most technologically advanced nutritional studies were also least likely to include female participants. 

Out of all the nutrient studies, only 17% included pregnant people or people who are lactating. 

“There's just this general idea, where people are concerned about including pregnant people because pregnant people are classified as a vulnerable population," Smith says. "For example, some researchers may be worried about risks to the fetus."

When people say they are excluding women from a vaccine trial or a nutrition trial because they don't want to potentially harm them, that population will then not have any nutrition, vaccine, or treatment that’s been tested on them, according to Smith.

Pregnant people should be protected through research rather than from research, Smith says.

They also found that under 10% of the analyzed studies identified a participant's race or ethnicity at all, meaning there’s little way to know whether minority populations are being represented fairly, underrepresented, or overrepresented.

Research About Essential Nutrients Is Lacking

There are two main takeaways this analysis drives home, according to Parul Christian, DrPH, MSc, director of the human nutrition program at John Hopkins University, who was not involved in the research.

The first is that, in general, existing scientific knowledge about requirements of essential nutrients in humans is likely incomplete and cannot be generalized.

This is especially true for the very critical life stages of pregnancy and lactation, which arguably set the health trajectories for the next generation. The problem is only exacerbated when researchers are not accounting for race, geography, or background. 

“‘Hidden hunger,’ which micronutrient deficiency is frequently called, is high in many under-resourced settings where food insecurity, chronic dietary inadequacy, and high burden of infection exist,” Christian tells Verywell. “In my years of research in low-income settings, where micronutrient deficiencies are high and linked with adverse birth outcomes and poor maternal health, there is a paucity of knowledge about the optimal levels at which of these nutrients can help.”

Looking to the Future

But if you are pregnant right now, there’s no need to be alarmed. There's enough information from real-world experience and clinical trials to determine that taking your prenatal vitamins, even at the levels they are today, is still beneficial to you and to your baby, according to Smith. 

“This paper here suggests that it could be better," Smith says. "So it's already good, but could it be better probably with additional information."

In an ideal world, scientists would be able to re-analyze all existing studies that include women and men to look for differences by sex.

“Doing just that can give us some understanding of what data we already have, whether or not there are differences," Smith says. "Because in some things there are sex differences and in others, there aren't."

But for now, Smith and Christian urge scientists to include women and pregnant people as much as possible in future research to course correct and rebalance their representation in scientific discussions.