Circulating Insulin-like Growth Factor-1 (IGF-1) is Associated with Vitamin A (VA) Status and Increased Circulating Hemoglobin (Hb) During Pregnancy in Nepalese Women

Erythropoiesis is compromised by vitamin A (VA) deficiency, and VA acts on the growth hormone/IGF-1 axis. Whether VA works through IGF-1 to enhance erythropoiesis in pregnancy has not been explored. We examined associations among mid-pregnancy retinol, IGF-1, iron status (ferritin and erythrocyte protoporphyrin) and Hb in 589 rural, pregnant, iron deficient women who participated in a placebo-controlled VA and β-carotene supplementation trial in Nepal. Associations of retinol to IGF-1 and IGF-1 to Hb or anemia were determined with linear and logistic regression. Path analysis was used to evaluate IGF-1 as a mediator between retinol and Hb, acting through or independently of iron status indicators. The interventions modestly increased IGF-1 (P = 0.09 for ANOVA), while each 0.1 μmol/L increment in retinol increased IGF-1 by 2.4 μg/L (p < 0.0001). Increments of 10 μg/L IGF-1 were associated with a 0.85 g/L increase in Hb (P < 0.0001) and a 15% reduced risk of moderate-to-severe anemia (p = 0.001). IGF-1 expl...