Proceedings of a Workshop
Nutrition During Pregnancy and Lactation
Exploring New Evidence
Proceedings of a Workshop—in Brief
The National Academies of Sciences, Engineering, and Medicine last reviewed the state of the science on nutrition during pregnancy and lactation 30 years ago with the publication of Nutrition During Pregnancy (IOM, 1990) and Nutrition During Lactation (IOM, 1991). In the intervening period, there have been advancements in evidence on nutrients, dietary patterns, nutritional supplements, and other nutrition-based topics relevant to pregnancy and lactation. On January 29–30, 2020, the Food and Nutrition Board of the National Academies convened a workshop in Washington, DC, to explore where new evidence has emerged. The workshop included, but was not limited to, discussion of the current state of the science on requirements for specific nutrients, relationships between intake during pregnancy and outcomes for the mother and child, alignment of dietary and supplement intake with existing recommendations, factors that affect lactation and human milk composition, and equity in access to nutritional care. This Proceedings of a Workshop—in Brief highlights key points made by participants and is not intended to provide a comprehensive account of the workshop.1
To set the stage for the workshop, the chair of the workshop planning committee, Anna Maria Siega-Riz of the University of Massachusetts Amherst, highlighted some of the major conclusions from the two previous Institute of Medicine reports. For instance, it was concluded that diet alone could meet the requirements for all known nutrients during pregnancy except iron (IOM, 1990) and that U.S. women were capable of fully nourishing their infants through breastfeeding (IOM, 1991). In the subsequent decades, there have been substantial changes in the state of the science, demographics, and health status of pregnant and lactating women, food environment, and dietary patterns in the population. Siega-Riz asserted that these two reports are now out of date and that consideration needs to be given to how new information can be provided to inform and guide the care of pregnant and lactating women.
Following Siega-Riz’s comments, a speaker from each of the workshop sponsors provided remarks on the alignment of the workshop with the work of her organization. Noting that the workshop included topics broadly related to maternal dietary issues, including nutritional status and dietary supplement use, Nancy Potischman of the Office of Dietary Supplements (ODS) at the National Institutes of Health thought it was well aligned with ODS’s mission “to strengthen knowledge and understanding of dietary supplements.” Next, Heather McMillan of Health Canada explained that she viewed the workshop as an opportunity to identify knowledge gaps, which, if filled, could inform future nutrition policy. Alison Steiber of the Academy of Nutrition and Dietetics outlined three priority topics for her organization that are pertinent to the workshop: improving peripregnancy health to improve the health of future generations, increasing breastfeeding support and related research, and collaborating on regulatory issues.
1 Presentations, videos, and other materials from the workshop can be found at http://nationalacademies.org/NutritionPregnancyand LactationWS (accessed April 9, 2020).
Maria Makrides of the South Australian Health and Medical Research Institute provided remarks on the specific health effects of omega-3 fatty acids. She explained that in an otherwise healthy population, maternal omega-3 fatty acids supplementation during pregnancy does not improve the child’s neurodevelopment and may have only a modest effect on childhood growth, if any at all. Given the mixed evidence on the effect on childhood allergy and asthma, she suggested that this is an area that merits further exploration. Such supplementation appears to reduce the risk of preterm birth. However, Makrides indicated that the benefits were likely limited to women with singleton pregnancies and a low omega-3 fatty acid status, and she said that supplementation may also increase post-term inductions or C-sections. Screening and monitoring a woman’s omega-3 fatty acid status during pregnancy is a promising strategy worthy of further investigation, she noted. When asked how women can meet their omega-3 fatty acid needs, Makrides thought that omnivorous women consuming at least one fatty-fish-containing meal per week would likely be replete and that the 2015–2020 Dietary Guidelines for Americans recommendation of 8–12 ounces of fish per week would probably be sufficient.
Rajavel Elango of The University of British Columbia and British Columbia Children’s Hospital discussed new evidence that challenges existing protein Dietary Reference Intake (DRI) values for pregnant women. The adult adequacy DRIs for protein, established in 2005, were derived from nitrogen balance study data. Using an approach called “indicator amino acid oxidation,”2 Elango and his colleagues estimated mean protein requirements of 1.2 and 1.52 g/kg/d during early and late pregnancy, respectively, which are higher than the existing protein Estimated Average Requirement (EAR) of 0.88 g/kg/d for pregnant women. Based on evidence from 212 healthy pregnant women from Vancouver, Canada, Elango noted that protein intake tends to align with these higher estimates. Although protein needs rise over the course of pregnancy, individual amino acid needs do not necessarily change at the same rate. Stressing the importance of protein quality, Elango emphasized that protein intake should be considered in the context of overall dietary energy intake. He indicated that well-nourished pregnant women likely do not need to consume protein beyond their normal intake and that the focus should be on protein variety.
In her presentation, Leanne Redman of the Pennington Biomedical Research Center reviewed the current evidence on carbohydrate and energy requirements. The EAR and Recommended Dietary Allowance (RDA) for total carbohydrates during pregnancy are 135 and 175 g/d, respectively. Redman showed that the mean total carbohydrate intake of pregnant women from developed countries has been estimated to be approximately 270 g/d. She further noted that the mean total dietary fiber intake among pregnant women, estimated to be about 19 g/d, falls below the fiber Adequate Intake (AI) of 28 g/d. The 2015–2020 Dietary Guidelines for Americans recommends that added sugars contribute less than 10 percent of total energy per day. Recent estimates indicate that pregnant women in the United States consume 15 percent of their total energy intake as added sugars, with a substantial portion coming from sugar-sweetened beverages. Moving on to outcome data, Redman stated that it is difficult to determine the harms and benefits of carbohydrates during pregnancy. Much of the work has focused on improving outcomes for women with gestational diabetes and their infants, but she noted that the quality of the body of evidence is low to very low, making it difficult to draw any conclusions. With respect to energy, requirements during pregnancy vary by prepregnancy weight status, physical activity level, and the different physiological demands across each trimester. Redman cited new evidence suggesting that women who have obesity can mobilize energy from their body’s fat stores and may not need to increase energy intake during pregnancy.
ONE-CARBON METABOLISM MICRONUTRIENTS
Yvonne Lamers of The University of British Columbia provided an overview of folate and vitamin B12 status during pregnancy and the possible implications for the child. She began by explaining that folate is critical for the closure of the neural tube during the first weeks of pregnancy. Accordingly, preconception folic acid supplementation is recommended, and several countries fortify foods with folic acid. Despite these efforts, a portion of women in the United States and Canada have red blood cell folate concentrations considered suboptimal for neural tube defect prevention. A subset of women also has excessive folate intake, which Lamers indicated is due to high-dose supplement use rather than intake from fortified foods. There is limited to no evidence to suggest that high-dose or prolonged folic acid supplementation is associated with birth weight or risk of preterm birth, asthma, autism, obesity, or insulin resistance. Lamers suggested that folate potentially serves other roles in development and health, possibly through epigenetic modifications. Lamers emphasized the importance of maternal vitamin B12 status during pregnancy, as fetal B12 stores
2 Elango explained that the indicator amino acid oxidation methodology uses stable isotopes to assess protein synthesis. The process is noninvasive and relies on breath samples.
are established in utero. She noted that vegetarians and certain ethnic groups are at risk for deficiency and thought that further exploration into vitamin B12 status during pregnancy and its interdependence with folate is warranted.
Marie Caudill of Cornell University discussed the growing body of evidence on the benefits of choline for mothers and their infants. She explained that choline serves many roles, including being vital for cell division, central nervous system development, and cellular methylation reactions. Choline demands are very high during pregnancy. Large amounts of choline are transferred to the fetus; infants are born with three to five times the choline concentrations of their mothers. Phosphatidylcholine, a choline derivative, is also delivered to the fetus. Free choline can be converted to phosphatidylcholine in the maternal liver via two pathways, which results in enrichment with different fatty acids. Concentrations of phosphatidylcholines enriched with long-chain polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), progressively increase from maternal circulation to the placenta to the cord blood, suggesting a unique requirement for the developing fetus. The synergy between choline and DHA and the implications of delivering these nutrients to the fetus is an active area of research, said Caudill. She then reviewed findings from studies indicating that higher maternal choline intake during pregnancy leads to reductions in neural tube defect, circulating cortisol levels, and placental production of a preeclampsia risk factor called sFLT1. Caudill also described improvements in some aspects of infant cognitive functioning with maternal choline supplementation. She stated that only 8 percent of pregnant women in the United States meet the choline AI of 450 mg/d and indicated that most leading prenatal vitamins do not contain choline. Caudill noted that breastmilk is a rich source of choline, with concentrations approximately 15 times higher than that of maternal blood.
IRON, VITAMIN D, CALCIUM, ANTIOXIDANTS, AND IODINE
Kimberly O’Brien of Cornell University presented evidence that has emerged related to iron, vitamin D, and calcium during pregnancy and lactation. O’Brien explained that iron needs increase dramatically during pregnancy to support the increase in red blood cell mass and the iron demands of both placenta and fetus. By contrast, iron needs during lactation are lower, because women who exclusively breastfeed tend to have amenorrhea and breastmilk iron content is low. The prevalence of iron deficiency increases as pregnancy progresses, but the prevalence of iron-deficiency anemia remains low throughout. O’Brien suggested that this might be due to inaccurate biomarker cutoffs for pregnant women or not appropriately adjusting values for stage of gestation, plasma volume expansion, or inflammation. Maternal iron supplementation during pregnancy improves hematological indexes, but more research is needed to understand the possible benefits and risks to both the mother and the fetus, she noted.
Moving on to vitamin D and calcium, O’Brien reminded the audience that the 2011 update of the DRI values for these two nutrients did not indicate an increased need during either pregnancy or lactation. She described evidence on vitamin D status during pregnancy and lactation as limited and indicated that there is no consensus in the field as to whether vitamin D supplementation is needed during pregnancy. With respect to calcium, few supplementation trials have assessed bone health during pregnancy. O’Brien contended that new techniques could be leveraged to look at bone morphology and growth over the course of gestation.
In her remarks about antioxidants, Corrine Hanson of the University of Nebraska Medical Center acknowledged that diet is one of the best defenses against the detrimental effects that oxidative stress is believed to cause. Dietary antioxidants are substances found in commonly consumed foods that have been found to decrease the adverse effects of reactive species in humans. Vitamin C, vitamin E, and selenium are dietary antioxidants. Other compounds do not meet the formal criteria to be classified as dietary antioxidants but are typically treated as such because of their influence on reactions involving the oxidative process (e.g., alpha-carotene, beta-cryptoxanthin, lutein, lycopene, zeaxanthin). Hanson underscored the importance of understanding antioxidant requirements during pregnancy, as fetuses and infants (particularly those that are premature) are exposed to conditions that could induce oxidative stress. Using data from a cohort of approximately 500 pregnant women in Nebraska, Hanson’s group found disparities in antioxidant status: living in a food desert, using public insurance, being non-white, and having some degree of food insecurity were each related to lower antioxidant status. Evidence relating maternal antioxidant status to outcomes in developed countries is often challenging to interpret, as participants’ nutritional antioxidant status is often sufficient, she noted. Relationships between antioxidant status and premature delivery and preeclampsia are inconsistent and depend on the antioxidant of interest. Findings from observational studies suggest higher vitamin E intake during pregnancy decreases the risk of some childhood respiratory outcomes, particularly wheeze, but Hanson reported that supplementation trials using vitamin C and vitamin E did not find an effect.
Next, Elizabeth Pearce of the Boston University School of Medicine reviewed the current evidence on iodine. She explained that thyroid hormone synthesis is the only known role for iodine in the body. During pregnancy, increases in maternal thyroid hormone and fetal production of thyroid hormone both require iodine as a substrate. Pearce indicated that severe iodine deficiency during pregnancy can impair children’s growth and intellectual development
and modest iodine deficiency likely affects their neurocognitive development. Iodine status can only be assessed at the population level—there is no biomarker that can be used for individuals. In the United States, women of reproductive age are most at risk for low urinary iodine concentrations and pregnant women are considered mildly iodine deficient. Although the United States has had a voluntary salt iodization program since the 1920s, Pearce pointed out that three-quarters of the salt consumed in the country comes from commercial foods that do not use iodized salt. Professional societies now recommend iodine-containing supplements for women who are planning to become pregnant or are pregnant or lactating. Despite this recommendation, a large proportion of U.S. prenatal multivitamins, particularly prescription vitamins, do not currently contain iodine, commented Pearce.
Regan Bailey of Purdue University presented findings from two recent National Health and Nutrition Examination Survey analyses that explored dietary supplement use in the United States. The majority of pregnant and lactating women report using dietary supplements, but this varies by age, race and ethnicity, income level, and stage of gestation. Micronutrient doses are incredibly variable across the supplements that they use, noted Bailey. For instance, based on median intake among pregnant women, dietary supplements provided 65 percent of the RDA for vitamin D but nearly 300 percent of the RDA for vitamin B12. Dietary supplements can help women meet nutrient requirement targets, but Bailey identified several nutrients for which total intake may still be below the recommended amount despite supplement use (e.g., magnesium, vitamin D, vitamin E). She also cautioned that supplementation could lead to excessive intake, particularly for folic acid and iron. Given this, she suggested pregnant and lactating women need better guidance on how to meet but not exceed intake recommendations.
To contextualize her remarks on prenatal supplement formulations, Laura Borgelt of the University of Colorado Anschutz Medical Campus showed labels from two prenatal multivitamin and mineral (PMVM) products to demonstrate the challenges consumers face in interpreting information presented in different ways. For instance, the two labels differed in the units used for folate, the percent Daily Value for the same quantities of calcium and vitamin D, and the forms of iron listed. Moving on to PMVM content, Borgelt reported that nonprescription products tend to have a greater number of vitamins and minerals and prescription formulations tend to have higher folic acid content, but she emphasized that more is not always better. Her lab analyzed a collection of prescription and nonprescription PMVM products and found that the content of many nutrients was higher than what was listed on the label (e.g., folic acid, niacin, riboflavin, vitamin A, vitamin D). She identified Consumer Lab, NSF International, and the United States Pharmacopeia as three of the top quality assurance companies that verify supplement contents, but she noted that quality is not a statement about safety or efficacy. Both the composition of the PMVM products and individual characteristics determine bioavailability, and Borgelt warned that drug interactions are possible.
NEW DEVELOPMENTS AND EMERGING TOPICS
Janet Thorlton of the University of Illinois at Chicago College of Nursing reviewed evidence on caffeine, which she described as the most widely consumed psychostimulant. The landscape and availability of caffeine-containing products has markedly changed over the past 20 years. Thorlton explained that manufacturers can decide to market some products as a nutritional item or dietary supplement, with differing labeling and regulatory guidelines for each. Dietary supplements fall under guidelines from the Dietary Supplement Health and Education Act, whereas foods and some beverages fall under regulatory guidelines from the Federal Food, Drug, and Cosmetic Act. Over the course of pregnancy, the half-life of caffeine progressively lengthens from 3–4 hours to 9–11 hours. Caffeine intake of up to 200 mg/d for pregnant women and 300 mg/d for lactating women is generally considered safe. Consumption of more than 200 mg/d caffeine during pregnancy may be associated with an increased risk of nonfatal myocardial infarction. During lactation, chronic caffeine intake can reduce breastmilk iron content and may lead to high plasma concentrations in neonates. Many factors influence the metabolism and pharmacokinetics of caffeine, including genetic variability, indicated Thorlton.
Kjersti Aagaard of the Baylor College of Medicine stated that the in utero environment shapes metabolic hereditability by establishing the offspring’s microbiome. There is limited evidence to support that intrauterine colonization or direct transplacental transfer of live microbes is the primary means by which maternal influences affect the offspring’s microbiome post-birth. Moreover, the phyla present in the infant’s gut in the first week of life do not correspond to the microbes constituting the vaginal microbiome. Instead, there are likely several mechanisms by which maternal exposures can shape the development of the offspring’s microbial ecology in utero. These include modulation of immune development, sparse but present selective microbial colonization of commensal organisms, and metabolic pruning of the
3 In the workshop agenda, this session was called “Nutritional Supplements.” The session heading was changed to align with the terminology used by session speakers.
developing microbial ecosystem. Aagaard’s group found that there were different infant microbiomes at birth and 4–6 weeks post-natal age, dependent on whether the mother consumed a high-fat diet (>30 percent energy from fat). Using nonhuman primate models, Aagaard’s team replicated these findings and demonstrated that the microbiome difference persisted over time and could not be corrected post-natally via a control diet after weaning. She cautioned that these data determine the metagenomically detected presence and characterization of the microbes but do not differentiate between those that are alive or not. In a study altering macronutrient intake of lactating women, changing the carbohydrate source (glucose versus galactose) and energy source (carbohydrates versus fat) altered human milk oligosaccharide (HMO) composition in different ways. These HMO changes, in turn, drove the milk microbiome’s functional community composition. Aagaard described HMOs as inert substances that cannot be metabolized by either the mother or the infant but are likely to be fundamental to the infant’s developing gut integrity and serve as food and fodder for microbes.
Michael I. Goran of Children’s Hospital Los Angeles and the University of Southern California explained that HMOs are compounds that are three or more sugars in length and highly abundant in human breastmilk. HMO composition appears to be highly variable among women and changes over time. HMOs are not absorbed by the infant and therefore serve as prebiotics. Turning to fructose, Goran stated that an infant’s natural feeding environment does not contain fructose and infants do not have the ability to absorb it until a sufficient amount is consumed in the diet. Fructose has been detected in breastmilk, and fructose content was found to be associated with infant body composition. In an acute feeding study, consumption of a high fructose corn syrup beverage elevated breastmilk concentrations of fructose but not glucose. The rise in fructose in breastmilk was rapid and sustained, as compared to a beverage containing a noncaloric sweetener. Goran described a longitudinal study currently under way that is exploring human breastmilk HMOs and fructose composition and changes in infant body composition and cognitive development. The findings suggest that HMOs act as a prebiotic and may have implications for gut microbiome development, infant feeding behaviors, and obesity development. To conclude his presentation, Goran noted that maternal intake of low-calorie sweeteners, which is increasing among pregnant women, increases a child’s risk of obesity at age 2. These sweeteners are also transmitted through breastmilk.
MATERNAL INTAKE AND NUTRITIONAL STATUS DURING LACTATION AND IMPLICATIONS FOR MATERNAL AND INFANT HEALTH
Lindsay Allen of the U.S. Department of Agriculture described the current state of evidence on the micronutrient composition of human milk as poor. Within the DRIs, infant AI values are derived using breastmilk composition data. There are several challenges in assessing human milk composition, including uncertainty about how best to collect the samples, how to analyze the samples properly, and what maternal characteristics need to be considered for correct interpretation. Allen’s lab developed efficient analytic techniques and approaches to analyze breastmilk composition. For many micronutrients, human milk concentrations globally are below the infant AI values. For instance, the concentration of 210 μg/L used to derive the thiamin AI for infants may be too high; median human milk thiamin from high-income countries has been estimated to be 125 μg/L. Similarly, vitamin B6 concentrations human milk globally are below the infant AI concentration of 0.13 mg/L, although a small sample of women from Davis, California, was found to have substantially higher concentrations (0.3 mg/L). Noting that the older analytic approaches for iodine were not valid, Allen said there is new evidence to suggest that the previous estimate of infant iodine needs are too high. Vitamin B12 human milk composition appears to be close to the previous estimates (310 pmol/L), although it is lower in countries where the intake of animal source foods is low. In closing, Allen remarked that maternal status before pregnancy is likely important for human milk concentrations and underscored the need to view these life stages as a continuum. When asked if there are recommendations related to breastmilk composition for women before, during, and after pregnancy, Allen responded that the World Health Organization does not provide recommendations on supplementation during lactation. She thought that until functional deficits or other detriments to infant growth, health, or development are defined, there would remain an absence of guidance during this life stage due to lack of investment.
In her remarks on the implications of maternal weight and metabolic status for lactation and breastmilk composition, Ellen Demerath of the University of Minnesota reminded the audience that over the past 30 years, rates of obesity, prediabetes, and diabetes have dramatically increased. Breastfeeding sets the stage for an infant’s metabolic expectations for growth, said Demerath. A concept called “lactational programming” posits that maternal nutrition, health, and other exposures affect breastmilk and, through molecular mechanisms, result in programmed offspring outcomes (see Figure 1). Despite the health benefits for mother and child, optimal breastfeeding is not always achieved. Demerath noted that lower levels of breastfeeding continuation have been reported among women with prepregnancy obesity. There are also data suggesting that maternal obesity delays and affects prolactin release and response, affecting the transfer of milk to the infant. Women with gestational diabetes may experience delayed onset
of lactation, which can be worsened by insulin treatment. Emerging studies suggest that the hormones leptin, insulin, and cortisol may play roles in lactation and can be transferred to the infant in a bioactive form via breastmilk. Maternal prepregnancy body mass index appears to be positively associated with milk leptin and insulin content. Demerath described emerging evidence suggesting a negative association between milk status and infant adiposity and weight status, indicating leptin may be functioning as an appetite suppressant in the infant.
Erica P. Gunderson of the Division of Research at Kaiser Permanente Northern California provided an overview of evidence on lactation and future risk of cardiometabolic disease in women. Gunderson stated that she viewed pregnancy and lactation as part of a continuum of the reproductive cycle rather than discrete life stages. She described the normal physiological changes of pregnancy as including “insulin resistance, highly variable glycemic excursions, and fat mass deposition, along with inflammation.” Complications during pregnancy may lead to women having higher risk for chronic disease at a younger age. Women who had gestational diabetes are at increased risk for type 2 diabetes and cardiovascular disease, she noted. Lactation may counteract some of these adverse effects of pregnancy on cardiometabolic risk factors and play a role in early prevention of chronic diseases. The Coronary Artery Risk Development in Young Adults Study, a rigorous prospective cohort study that began data collection during the preconception period, found a strong inverse relationship between increased breastfeeding duration and reduced incidence of metabolic syndrome and type 2 diabetes in black and white women across the reproductive years, reported Gunderson. Similarly, the Study of Women, Infant Feeding, and Type 2 Diabetes After GDM4 Pregnancy, a prospective longitudinal cohort of women with gestational diabetes, found a strong inverse association between breastfeeding duration and intensity with incidence of type 2 diabetes up to 2 years after delivery, independent of prenatal glucose tolerance, perinatal outcomes, and behavioral risk factors. Gunderson said that these findings suggest breastfeeding may have stronger metabolic consequences to lower the risk of diabetes and cardiovascular diseases than previously appreciated.
MATERNAL NUTRIENT INTAKE AND EARLY LIFE PROGRAMMING
Leslie Myatt of Oregon Health & Science University presented on the various roles the placenta plays during pregnancy. Describing the placenta as a “selfish organ,” Myatt noted that it regulates the type and flow of nutrients, with the
4 GDM is gestational diabetes mellitus.
fetus receiving what the placenta does not consume. It achieves this through adaptive mechanisms regulating maternal metabolism to control the supply of substrates, changing transporter expression, buffering, and storing select nutrients and changing its own metabolism to alter or limit transfer to the fetus. The placenta grows and develops over the course of gestation, and there may be critical periods during which insults can lead to different effects. He explained that women with type 2 diabetes who were hyperglycemic at the beginning of pregnancy expressed different placental transporters than women who developed hyperglycemia later in pregnancy due to gestational diabetes. Myatt further noted that the DNA methylation of the offspring differed if the mother was in her first or third trimester during the Dutch Hunger Winter.5 Maternal obesity appears to increase placental DNA methylation, and these changes often resulted in differences in gene expression. Myatt described sexual dimorphism in placental gene expression and suggested that this may lead to differences in male versus female fetal outcomes.
Following Myatt’s presentation, Aagaard, Goran, and Myatt participated in a panel discussion moderated by Emily Oken of Harvard Medical School and Harvard Pilgrim Health Care Institute. To open the discussion, Oken asked each of the panelists to identify what they viewed as clear next steps and highest-yield interventions. Goran responded that limiting sugar exposure is key, as it has caloric, metabolic, and developmental implications and leads to shifts toward a more wholesome diet. Aagaard offered three ideas: (1) finding ways to intervene during the periconception period; (2) taking a global-centric view of nutrition so that diets can be closer to the source and sustainable; and (3) improving maternal diets to improve breastmilk composition. Myatt indicated that key targets should be obesity and gestational diabetes, as they are pervasive in the population and they both affect the placenta. Oken also asked the panelists if any of the research they discussed in their presentations was ready for clinical application. Suggesting that pregnant women undergo limited testing during pregnancy, Myatt thought it was time to start incorporating testing for placental health. From Aagaard’s perspective, tests are performed in the clinical setting to inform management or to improve an outcome. She indicated that microbiome work is not yet ready for clinical settings, as the directionality of change is not known and may be beneficially adaptive over time. Similarly, Goran indicated that the work on oligosaccharides is currently only for research purposes.
THE ROLE OF SYSTEMS AND POLICIES PROVIDING SOLUTIONS TO NUTRITION ACCESS AND EQUITY IN PREGNANCY AND LACTATION
In his remarks on system changes for improving maternal nutrition, Rafael Pérez-Escamilla of the Yale School of Public Health emphasized that suboptimal health and nutrition outcomes among pregnant and lactating women are strongly tied to socioeconomic inequities. Pérez-Escamilla indicated the underlying cause of these inequities is social injustice. He suggested that systems approaches across the lifespan are needed to address the existing inequities and that these should be guided by the principles of implementation science.
Kate Keenan of The University of Chicago explained that exposure to stress during pregnancy has implications for prenatally programming offspring behavioral and emotional function and understanding racial disparities in health. A nutritional intervention that can help modulate maternal stress may lead to improved infant neurodevelopment, she suggested. In a pilot study, Keenan’s team conducted a double-blind, placebo-controlled, randomized trial of omega-3 fatty acid supplementation in pregnant black American women with Medicaid insurance. Compared to the placebo group, the supplemented mothers had lower perceived stress at 30 weeks gestation, and their infants had a more modulated cortisol response to a stress test.
Stress and food insecurity are key factors that affect nutrition and shape metabolism, said Barbara Laraia of the University of California, Berkeley, to provide context for her remarks. Her group developed a mindfulness-based intervention that aimed to reduce stress, improve nutrition, and increase physical activity. Intervention participants had significant reductions in stress and scored lower on an oral glucose tolerance test, as compared to participants in the control group. Laraia also described efforts to reduce food insecurity during pregnancy in San Francisco. Recognizing food insecurity is a social, emotional, and logistical issue, the city is colocating federal food programs to make access easier.
Darlena Birch of the National WIC6 Association (NWA) explained that her organization provides member-driven advocacy and seeks to educate, guide, and support WIC staff. To better address heath disparities and inequities, NWA is shifting toward a health equity framework. Birch pointed to the Breastfeeding Peer Counseling Program as one example of how the WIC program is currently addressing health equity and striving to close the breastfeeding gap. She noted that legislation can help or hinder program eligibility, access, and participation.
After their presentations, the four session speakers took part in a panel discussion, moderated by Angela Odoms-Young of the University of Illinois at Chicago. Odoms-Young asked each speaker to reflect on the implications
5 The Dutch Hunger Winter was a famine that took place in the Netherlands during the winter of 1944–1945.
6 WIC is the Special Supplemental Nutrition Program for Women, Infants, and Children.
of the current state of the science on nutrition during pregnancy and lactation. Keenan felt that pregnant women are quite good at using information provided to them by the clinical-scientific community to improve their health. Thinking about the food supply, Laraia suggested that available and accessible foods need to reflect dietary recommendations. Pérez-Escamilla emphasized the importance of focusing on dietary patterns across the lifespan. Birch thought that there is tremendous opportunity for continued research. Panelists were also asked about examples from other countries that could serve as a model for nutrition and breastfeeding counseling. Birch discussed how breastfeeding is more culturally acceptable in other parts of the world, which creates a community of support for the lactating woman. Building on this, Pérez-Escamilla underscored the importance of a woman receiving lactation support—particularly in the first 2 weeks postpartum—from well-trained, qualified professionals. Laraia raised the issue of maternal and paternal leave.
REFLECTIONS ON THE WORKSHOP
In the last session, Patsy Brannon of Cornell University reflected on the presentations and discussions that took place across the 2 days. She noted that evidence has emerged in several key areas, including protein and energy needs, one-carbon metabolism micronutrients, developmental origins of health and disease, obesity, gestational diabetes, and health equity. She highlighted some crosscutting themes, such as issues related to biomarkers and physiological adjustments; supplements’ need, dose, form, interaction with baseline status, and bioavailability; the concept of a reproductive continuum from the prepregnancy through postpartum periods; and the issues of developmental origins of adult health and disease. Considering the strong inequities that exist related to social injustice, Brannon emphasized the need to better understand the underlying framework related to these factors and the importance of using implementation science to inform approaches across different systems. ◆◆◆
IOM (Institute of Medicine). 1990. Nutrition during pregnancy: Part I: Weight gain, Part II: Nutrient supplements. Washington, DC: National Academy Press.
IOM. 1991. Nutrition during lactation. Washington, DC: National Academy Press.
DISCLAIMER: This Proceedings of a Workshop—in Brief was prepared by Meghan Harrison as a factual summary of what occurred at the workshop. The statements made are those of the rapporteur or individual workshop participants and do not necessarily represent the views of all workshop participants; the planning committee; or the National Academies of Sciences, Engineering, and Medicine.
*The National Academies of Sciences, Engineering, and Medicine’s planning committees are solely responsible for organizing the workshop, identifying topics, and choosing speakers. The responsibility for the published Proceedings of a Workshop—in Brief rests with the rapporteur and the institution.
Anna Maria Siega-Riz (Chair), University of Massachusetts Amherst
Patrick Catalano, Tufts School of Medicine
Erica P. Gunderson, Kaiser Permanente Northern California
Tamera Hatfield, University of California, Irvine
Deborah O’Connor, University of Toronto
Angela Odoms-Young, University of Illinois at Chicago
Emily Oken, Harvard Medical School and Harvard Pilgrim Health Care Institute
REVIEWERS: To ensure that it meets institutional standards for quality and objectivity, this Proceedings of a Workshop—in Brief was reviewed by Stephanie Atkinson, McMaster University; Carol Dreibelbis, 1,000 Days; and Justine Kavle, The George Washington University Milken Institute School of Public Health. Lauren Shern, National Academies of Sciences, Engineering, and Medicine, served as the review coordinator.
SPONSORS: This activity was partially supported by the Academy of Nutrition and Dietetics, Health Canada, and the National Institutes of Health (Office of Dietary Supplements) with additional support from the Kellogg Endowment Fund of the National Academies of Sciences, Engineering, and Medicine’s Health and Medicine Division.
For additional information regarding the workshop, visit http://nationalacademies.org/NutritionPregnancyandLactationWS.
Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2020. Nutrition during pregnancy and lactation: Exploring new evidence: Proceedings of a workshop—in brief. Washington, DC: The National Academies Press. https://doi.org/10.17226/25831.
Health and Medicine Division
Copyright 2020 by the National Academy of Sciences. All rights reserved.