Utilization of Iron in the Third Trimester of Pregnancy in Women with and Without Pre-pregnancy Obesity (P24-013-19)

Abstract

Abstract Objectives Obese women may be at risk for poor iron status in pregnancy due to pro-inflammatory driven overexpression of hepcidin that leads to decreased iron bioavailability. Our objective was to determine the impact of pre-pregnancy (PP) obesity on maternal iron utilization in the third trimester of a singleton pregnancy. Methods Using the stable isotope 57Fe prepared as an oral ferrous sulfate solution, we measured iron absorption based on red blood cell incorporation in 50 adult (mean age: 27.6 ± 6.8 years) pregnant women [n = 29 PP non-obese (body mass index (BMI) 18.5–29.9 kg/m2) and n = 21 PP obese (BMI ≥ 30.0 kg/m2] at the 32nd-34th gestational week (mean 32.7 ± 0.7 weeks). We also assessed maternal iron status, hepcidin, inflammation, erythropoietin, dietary iron intake and gestational weight gain. Results Iron deficiency defined as hemoglobin < 11.0 g/dL was highly prevalent (PP obese 67% vs. PP non-obese 48%, P = 0.19). 57Fe utilization (PP non-obese 11.2% (interquartile range (IQR), 8.3) vs. PP obese 7.7% (IQR 8.9), P = 0.23), hepcidin, hemoglobin, and soluble transferrin receptor was similar between the PP BMI groups. PP obesity was associated with significantly higher ferritin, high sensitivity C-reactive protein, and total body iron. In the women who were non-obese PP, 57Fe utilization was not linearly associated with any of the iron-related or inflammatory indices tested. However, 57Fe utilization was significantly inversely associated with serum ferritin (r = −0.42) and serum hepcidin (r = −0.48) in women with PP obesity. In post-hoc analysis, compared to non-obese women, iron utilization was 23% lower in women with class 2 and 3 PP obesity and 3% lower in women with class 1 PP obesity, respectively. Conclusions Iron utilization from an oral ferrous sulfate solution in the third trimester of pregnancy was similar in women with and without PP obesity. Given the growing prevalence of class 2 and 3 obesity among reproductive age women, and the importance of iron for optimal maternal and fetal health, our post-hoc analysis suggests that future efforts should examine iron utilization in women with severe PP obesity. Funding Sources Robert Wood Johnson Foundation, Nurse Faculty Scholars Program #72,117 and University of Illinois at Chicago Colleges of Nursing and Medicine.