Iron status, body size, and growth in the first 2years of life.

Abstract

Rapid growth in infancy has been shown to adversely affect iron status up to 1year; however the effect of growth on iron status in the second year of life has been largely unexplored. We aimed to investigate the impact of growth and body size in the first 2years on iron status at 2years. In the prospective, maternal-infant Cork BASELINE Birth Cohort Study, infant weight and length were measured at birth, 2, 6, 12, and 24months and absolute weight (kg) and length (cm) gain from 0 to 2, 0 to 6, 0 to 12, 6 to 12, 12 to 24, and 0 to 24months were calculated. At 2years (n=704), haemoglobin, mean corpuscular volume, and serum ferritin (umbilical cord concentrations also) were measured. At 2years, 5% had iron deficiency (ferritin<12μg/L) and 1% had iron deficiency anaemia (haemoglobin<110g/L+ferritin<12μg/L). Weight gain from 6 to 12, 0 to 24, and 12 to 24months were all inversely associated with ferritin concentrations at 2years but only the association with weight gain from 12 to 24months was robust after adjustment for potential confounders including cord ferritin (adj. estimate 95% CI: -4.40 [-8.43, -0.37]μg/L, p=.033). Length gain from 0 to 24months was positively associated with haemoglobin at 2years (0.42 [0.07, 0.76]g/L, p=.019), only prior to further adjustment for cord ferritin. To conclude, weight gain in the second year was inversely associated with iron stores at 2years, even after accounting for iron status at birth. Further examinations of iron requirements, dietary intakes, and growth patterns in children in the second year of life in high-resource settings are warranted.