Work

Iron Status from Early Through Late Pregnancy and Neonatal Anthropometric Measures: Friend or Foe?

Year: 2020

Type: article

Abstract: Although iron status in pregnancy is an important factor for fetal growth, associations between maternal iron status and neonatal size are highly conflicting. Further, studies with longitudinal measures of iron status in pregnancy are scarce. This study investigated maternal iron status from early through late pregnancy using comprehensive measures of iron biomarkers (ferritin, hepcidin, soluble transferrin receptor [sTfR], and sTfR: ferritin ratio) in relation to neonatal size. This study included 321 pregnant women without major chronic conditions before pregnancy who were enrolled in the NICHD Fetal Growth Study- Singletons (n = 2802). Plasma iron biomarkers (i.e., ferritin, sTfR, hepcidin) were measured at 4 visits (10–14, 15–26, 23–31, and 33–39 gestational weeks [GW]). We used linear and Poisson regression models adjusted for covariates including pre-pregnancy BMI and C-reactive protein to estimate the association of tertiles (T) of iron biomarkers and clinically defined iron status with neonatal anthropometry, such as birthweight (BW), risk of large and small-for-gestational age (LGA, SGA) and macrosomia. Iron deficiency (i.e., ferritin <12 ug/L) at 10–14 GW was related to increased risk of macrosomia and LGA; adjusted RR (95% confidence interval (CI)) were 3.64 (1.45, 9.17), and 14.2 (5.49, 36.4), respectively. At 15–26 GW, iron deficiency was also related to increased risk of LGA with a RR of 3.58 (1.13, 11.4). In contrast, at 33–39 GW, iron deficiency was related to lower risk of macrosomia with a RR of 0.06 (0.01, 0.36). The CIs were wide, largely due to small sample size of macrosomia cases. In addition, at 10–14 GW, lower iron status (indicated by higher sTfR levels) was related to greater BW; highest vs. lowest T mean BW was 3385 g vs. 3251 g with an adjusted p-value for difference <0.05. Our findings among U.S. pregnant women without major chronic conditions before pregnancy suggest that the relation of maternal iron status to neonatal size may vary by gestational age and lower iron status in early pregnancy is generally related to heavier neonates. Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)/National Institutes of Health (NIH).

Source: Current Developments in Nutrition

DOI: 10.1093/cdn/nzaa054_075