Macronutrient and Micronutrient Intake Among US Women Aged 20 to 44 Years

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.