Some subgroups of U.S. childbearing women are still at risk of iodine deficiency in the 21 st century: a cross-sectional analysis of NHANES 2001-2020.

backgroundIodine deficiency remains a significant public health issue, especially among women of childbearing age. Assessing iodine nutrition in this population is crucial for the timely prevention of iodine deficiency disorders.

methodsThis cross-sectional and trend analysis utilized data from nine NHANES survey cycles (2001–2020). Urinary iodine concentrations (UIC) were analyzed from 6,828 women aged 14–45 years, categorized into the following subgroups: pregnant (n = 504), lactating (n = 149), and non-pregnant non-lactating women (n = 385). Iodine adequacy was defined using WHO criteria: median UIC of 150–249 µg/L for pregnant women, ≥ 100 µg/L for lactating women, and 100–199 µg/L for non-pregnant non-lactating women. Weighted median UIC, the proportion of individuals below these thresholds, and their respective time trends were assessed using survey-based methods to account for the complex sampling design.

resultsThe median UIC among all women of childbearing age significantly declined from 135.0 µg/L (2001–2002) to 103.5 µg/L (2017–2020), while the proportion of population with UIC < 100 µg/L increased from 37.6% to 47.7%. The median UIC for both pregnant and lactating women fell below the adequate range during 2007–2014 (138.6 µg/L and 70.6 µg/L, respectively) and 2015–2020 (142.8 µg/L and 100.7 µg/L, respectively). Non-Hispanic Black pregnant women and older lactating women (35–45 years) exhibited notably lower median UIC.

conclusionsIodine deficiency persists as a public health concern among U.S. women of childbearing age, particularly among pregnant and lactating subgroups. Continuous monitoring and targeted public health interventions are recommended to ensure adequate iodine nutrition in these high-risk populations.