Iron deficiency anemia and health equity: Persistent gaps among reproductive-age women in the United States

Abstract Background: Iron deficiency anemia (IDA) is the most prevalent hematologic disorder among reproductive age women and a persistent public health challenge. Pregnancy increases iron requirements, heightening risk of adverse maternal and neonatal outcomes. Socioeconomic disparities strongly influence IDA risk, reinforcing health inequities. The COVID-19 pandemic disrupted healthcare, nutrition, and income stability, which are directly tied to iron status. This study examines IDA prevalence, risk factors, and trends in women aged 18 to 49 years, stratified by pregnancy status, before and during the pandemic. Methods: We analyzed the National Health and Nutrition Examination Survey data from 2015 to 2016, 2017 to 2018, and 2021 to 2023 for women aged 18 to 49 years, stratified by pregnancy. IDA was defined per WHO criteria: hemoglobin <12 g/dL (non-pregnant) or <11 g/dL (pregnant), and ferritin <15 ng/mL if C-reactive protein (CRP) <5 mg/L or <70 ng/mL if CRP ≥5 mg/L. Complex survey weights were used. Covariates included age, race/ethnicity, education, poverty-income ratio (PIR), BMI, food insecurity, dietary iron intake (≥18 mg/day for non-pregnant; ≥27 mg/day for pregnant), and iron supplementation (≥30 mg/day). Statistical analysis was conducted using Rao-Scott chi-square and multivariable logistic regression. Results: Among non-pregnant women aged 18 to 49 years, the overall prevalence of IDA was highest in those aged 35 to 49 years (9.5%) and lowest in the 18 to 24 years group (6.7%). Significant racial disparities were observed, with the highest prevalence in non-Hispanic Black women (19.0%), followed by Mexican American and other Hispanic women (both 11.7%), and the lowest in non-Hispanic White women (3.8%, p<0.001). Education status was inversely associated with IDA, with the lowest rates among college-educated women (6.1%) and the highest among those with less than or equal to high school education (12.5 and 12.7% respectively, p<0.001). Socioeconomic status significantly influenced IDA risk. Women with a PIR <1 had the highest prevalence (10.9%) compared to 7.0% in those with PIR >2 (p=0.018). IDA was more common in obese women (10.3%, p=0.0041) and in those with food insecurity (9.8% vs. 6.6%, p=0.004). No association was found between sufficient dietary iron intake and IDA (p=0.11), although women with IDA were significantly more likely to report iron supplementation (20.3% vs 7.6%, p<0.001). There was no significant trend in IDA prevalence from 2015 to 2016 (8.25%), 2017 to 2018 (7.0%) and 2021 to 2023 (8.75%, p=0.49). In multivariable analysis, age 35 to 49 years, (aOR=1.52, 95% CI [1.10, 2.10]), non-Hispanic Black women (aOR=1.99, 95% CI [1.25, 3.16]), obesity (aOR=1.43, 95% CI [1.00, 2.00]), and iron supplementation (aOR=2.92, 95% CI [2.05, 4.18]) were independently associated with higher odds of IDA. College education was protective (aOR=0.59, 95% CI [0.40, 0.86], p=0.007). Among pregnant women aged 18 to 49 years, the prevalence of IDA was highest in those aged 18 to 24 years (14.85%). While racial differences were not significant (p=0.36), the highest IDA prevalence was observed in women identifying as Others or multiracial (19.4%) and lowest in non-Hispanic White women (6%). Education status was inversely associated with IDA prevalence, with lowest rates among college-educated women (5.5%) and highest among those with less than high school education (21.9%, p=0.027). Women with a PIR of 1-1.99 had the highest prevalence (19.3%) compared to 3.9% in those with PIR >2 (p=0.03). Obesity, food insecurity, sufficient dietary iron, and iron supplementation were not significantly associated with IDA. Although there was no significant trend in IDA prevalence from 2015 to 2016 (6.63%), 2017 to 2018 (8.83%) and 2021 to 2023 (9.9%, p=0.76), it demonstrated an increasing trend over the past decade. In multivariate models, no sociodemographic factor was independently associated with IDA in pregnancy. Conclusion: IDA remains a substantial burden among reproductive-age women in the U.S. with significant racial disparities. COVID-19 may have intensified vulnerabilities, with increasing prevalence in pregnant women. Compared to non-pregnant women, pregnant women with PIR<1 did not have a higher prevalence of IDA, possibly related to pregnancy being a potential qualifier for public aid benefits. However, more studies are needed for targeted, equity-focused interventions to reduce disparities and improve outcomes.