Maternal anemia, iron intake in pregnancy, and offspring blood pressure in the Avon Longitudinal Study of Parents and Children

Background: In animals, maternal iron deficiency during pregnancy results in elevated offspring blood pressure (BP). Studies in pregnant women are limited in number, have had inconsistent results, and have not accounted for maternal iron supplementation. Objective: The objective was to assess the association between maternal iron status during pregnancy and offspring BP. Design: Maternal hemoglobin (n = 1255), iron supplementation ( n = 7484), food-based iron intake ( n = 7130), and offspring BP were assessed in a prospective cohort at 7 y of age. Results: Maternal anemia during pregnancy was associated with lower systolic BP in the offspring at 7 y of age (third trimester, age- and sex-adjusted: beta = -1.09; 95% CI: -2.21, -0.05 mm Hg; P = 0.04). Adjustment for confounders attenuated this association ( beta = -0.49; 95% CI: -1.71, 0.72 mm Hg; P = 0.4). In women who did not take iron supplements during pregnancy, the observed association with maternal anemia was even stronger: minimally adjusted models ( beta = -2.11; 95% CI: -3.61, -0.61 mm Hg; P = 0.006) and fully adjusted models ( beta = -1.48; 95% CI: -3.21, 0.25 mm Hg; P = 0.09). Iron supplementation was not associated with offspring BP after confounding by multivitamin intake was accounted for, and no association with iron intake from food was observed. Conclusion: In contrast with animal studies, maternal iron intake during pregnancy is not associated with offspring BP, and some evidence indicates that maternal anemia in contemporary pregnant women is associated with lower offspring BP. It is possible that, in well-nourished populations, low hemoglobin is more likely to reflect greater plasma volume expansion (and thus better maternal and offspring health) than iron deficiency.