(P18-012-23) The Relation Between Pre-Pregnancy BMI or Race/Ethnicity and Iron Status in US Pregnant Women: Results From the NHANES (1999–2010) Study

Objectives: Previous US studies linked poor iron status during pregnancy with both pre-pregnancy BMI and race/ethnicity but did not use nationally representative data. Thus, we examined the association between pre-pregnancy BMI or race/ethnicity and iron status in US pregnant women.

Methods: We used the National Health and Nutrition Examination Survey (NHANES; (1999-2010)) for pregnant women (18-44 years). BMI (kg/m²) was calculated using self-reported pre-pregnancy weight and height measured at examination and classified by the WHO categories. Iron deficiency (ID), defined as total body iron < 0 mg/kg, was calculated from serum ferritin and transferrin receptor using Cook’s equation. Anemia was defined as hemoglobin < 11 g/dL. Associations were examined using logistic regression models, adjusted for confounders (age, education, family income, and trimester).

Results: Pregnant women were on average 27 years old (n=1,157), of which 53% were non-Hispanic White, 21% Hispanic, and 14% non-Hispanic Black. The prevalence of ID and anemia was 14% and 8%, respectively and of pre-pregnancy overweight and obesity was 22% and 21%, respectively. There were similar odds between pre-pregnancy overweight or obesity and ID (overweight, adjusted odds ratio (OR)=1.41, 95%CI: 0.85-2.32; obesity, OR=0.70, 95%CI: 0.31-1.56) and between pre-pregnancy overweight or obesity and anemia (overweight, OR=1.09, 95%CI: 0.48-2.49; obesity, OR=0.99, 95%CI: 0.44-2.24), when compared to normal BMI. Non-Hispanic Black women had higher odds of ID (2.33, 95%CI: 1.03-5.29) and anemia (6.76, 95%CI: 2.64-17.30) than their non-Hispanic White counterparts.

Conclusions: These US nationally representative data showed that iron status in pregnancy may differ by race/ethnicity. Non-Hispanic Black pregnant women had a 2-fold increase in the odds of ID and nearly 7-fold increase in the odds of anemia. Future studies are warranted to confirm these findings and to examine potential underlying reasons.

Funding Sources: There was no funding for this project.