The objectives of the present study in rural Nepali pregnant women living in the terai were: (1) to identify the risk factors of severe anemia and investigate whether risk factors for anemia without iron deficiency, iron deficiency without anemia and iron deficiency anemia (IDA) were different; (2) to examine the effect of vitamin A supplementation, alone or combined with iron, on hemoglobin (Hb) and soluble transferrin receptor (sTfR); and (3) to identify the risk factors of low birth weight (LBW) and preterm delivery, focusing on maternal Hb concentrations. The prevalence of severe anemia (Hb < 8.0 g/dl) in this population (n = 3531) was 4.2% and that of iron deficiency was 31%. Logistic regression analyses indicated that risk factors of severe anemia included hookworm infestation, impaired dark adaptation, lack of iron supplement intake, a diet low in heme iron and malnutrition manifested by thinness and short stature. These same factors differed among non-iron-deficient anemic, iron deficient non-anemic, and iron-deficient anemic pregnant women. We found a significant positive correlation between Hb and retinol concentrations (Pearson r = 0.212, P < 0.0001) and one fourth of our anemic subjects were also vitamin A deficient. There was no evidence that vitamin A alone significantly increased Hb and decreased the prevalence of anemia (n = 498). However, vitamin A, when given together with iron, had an added beneficial effect on Hb but not sTfR. In addition, women with initially compromised iron status benefited more from iron and vitamin A supplementation. The prevalence of LBW and preterm delivery was 22% and 20%, respectively (n = 915). There was an increased risk of LBW associated with short stature, thinness and impaired dark adaptation. The association between Hb measured during the second trimester and risk of LBW had a U-shaped distribution, with risk increasing significantly with Hb < 8.0 g/dl. Based on our findings, we recommend that Hb is evaluated during the second trimester as an indicator of increased LBW risk. While vitamin A supplementation to all pregnant women is recommended, routine supplementation of iron and deworming during pregnancy are essential.