Dietary intakes of iron, folate, and vitamin B12 during pregnancy and correlation with maternal hemoglobin and fetal growth: findings from the ROLO longitudinal birth cohort study

Purpose Dietary micronutrient intakes of iron, folate and vitamin B12 are known to influence hemoglobin. Low maternal hemoglobin (maternal anemia) has been linked to low birthweight and other adverse health outcomes in the fetus and infant. Our primary aim was to explore relationships between maternal dietary micronutrient intakes, maternal full blood count (FBC) parameters and fetal abdominal circumference (AC) and estimated fetal weight (EFW) growth trajectories. Secondarily, we aimed to assess relationships between maternal dietary micronutrient intakes, maternal hemoglobin values and placental weight and birthweight. Methods Mother–child pairs ( n = 759) recruited for the ROLO study were included in this analysis. Maternal dietary micronutrient intakes were calculated from food diaries completed during each trimester of pregnancy. FBC samples were collected at 13- and 28-weeks’ gestation. Fetal ultrasound measurements were recorded at 20- and 34-weeks’ gestation. Growth trajectories for AC and EFW were estimated using latent class trajectory mixture models. Results Dietary intakes of iron and folate were deficient for all trimesters. Mean maternal hemoglobin levels were replete at 13- and 28-weeks’ gestation. Dietary iron, folate and vitamin B12 intakes showed no associations with fetal growth trajectories, placental weight or birthweight. Lower maternal hemoglobin concentrations at 28 weeks’ gestation were associated with faster rates of fetal growth and larger placental weights and birthweights. Conclusion The negative association between maternal hemoglobin at 28 weeks’ gestation and accelerated fetal and placental growth may be due to greater consumption of maternal iron and hemoglobin by fetuses’ on faster growth trajectories in addition to placental biochemical responses to lower oxygen states.