Abstract
IMPORTANCE: Nutritional status before and during pregnancy is important for maternal health and fetal growth and development. OBJECTIVE: To describe secular trends in nutrient intake from foods, beverages, and supplements among pregnant and nonpregnant women of reproductive age in the US. DESIGN, SETTING, AND PARTICIPANTS: This was a secondary series of cross-sectional analyses of the 1999-2018 National Health and Nutrition Examination Survey (NHANES). Pregnant (n = 1392) and nonpregnant (n = 9737) women aged 20 to 44 years who provided at least 1 reliable dietary recall were included for analysis. These analyses were performed between February 2022 and July 2024. MAIN OUTCOMES AND MEASURES: The primary outcomes included the mean usual intake of macronutrients and micronutrients, as well as the prevalence of inadequate intake of micronutrients. RESULTS: This representative sample included 1392 pregnant women (mean [SE] age, 28.5 [0.3] years) and 9737 nonpregnant women (mean [SE] age, 32.2 [0.1] years). Among pregnant women, a weighted mean (SE) of 27.0% (1.8%) of women were in their first trimester, and 33.8% (2.2%) were in their second trimester. Mean (SE) carbohydrate intake decreased between 1999-2000 and 2013-2018 among pregnant women (306.9 [7.6] to 274.9 [5.7] g/d; β = -2.1 [0.4]; P < .001) and between 1999-2000 and 2017-2018 among nonpregnant women (251.9 [4.9] to 216.9 [3.3] g/d; β = -1.9 [0.4]; P = .002). Between 1999-2000 and 2013-2018, the proportion of pregnant women who consumed below the Estimated Average Requirement of vitamin A increased by 10.9 percentage points (pp) (95% CI, 5.2-16.7 pp), and the proportion of pregnant women who consumed below the Estimated Average Requirement of vitamin C increased by 8.9 pp (95% CI, 3.9-14.0 pp). Similarly, the proportion of nonpregnant women with inadequate intake of vitamin A, vitamin C, and iron increased by 19.9 pp (95% CI, 12.3-27.5 pp), 11.1 pp (95% CI, 4.5-17.7 pp), and 4.9 pp (95% CI, 1.7-8.2 pp), respectively, between 1999-2000 and 2017-2018. The mean (SE) calcium intake increased from 1120.6 (41.4) to 1308.7 (49.0) mg/d for pregnant women (β = 11.7 [4.3]; P = .03) and from 849.5 (19.8) to 981.2 (27.9) mg/d for nonpregnant women (β = 6.7 [2.6]; P = .03; β2 = -1.3 [0.2]; P < .001). Among pregnant women, the prevalence of inadequate intake decreased by 16.1 pp (95% CI, 8.3-23.9 pp) for magnesium (P < .001) and 33.2 pp (95% CI, 24.0-42.4 pp) for vitamin K (P < .001); among nonpregnant women, the proportion with inadequate intake decreased by 16.1 pp (95% CI, 10.4-21.7 pp) for calcium (P < .001), 15.5 pp (95% CI, 7.3-23.6 pp) for magnesium (P < .001), and 33.3 pp (23.5-43.0 pp) for vitamin K (P < .001). CONCLUSIONS AND RELEVANCE: This cross-sectional study of pregnant and nonpregnant women of reproductive age found that vitamin A, vitamin C, and iron intake decreased over the past 2 decades, which may have substantial maternal and fetal health implications. By identifying these nutrient gaps and trends in inadequate intake in this at-risk population, scientific, health care, and regulatory communities may be better poised to adopt recommendations to improve nutrient intake.