Association between maternal haemoglobin at 27-29 weeks gestation and intrauterine growth restriction

Objective: To examine the relationship between maternal haemoglobin concentration (Hb) at 27-29 weeks' gestation and fetal growth restriction (FGR). Design: This was a retrospective, case control study. Setting: A University hospital in London, UK. Population: Pregnant women attending for routine antenatal care at 27-29 weeks of pregnancy. Methods: Maternal Hb, measured routinely at 27-29 weeks in pregnancies complicated by FGR (n = 491) was compared to normal controls (n = 491). Multiple regression analysis was used to examine the association between Hb and maternal characteristics. Main outcome measures: Birthweight z-score, admission to the Neonatal Unit (NNU) and adverse perinatal outcome. Results: Increased Hb at 27-29 weeks gestation is associated with reduced birthweight, with an inverse relationship between maternal Hb and fetal birthweight z-score (R-2 = 0.10, p < 0.0001). In addition, for the prediction of admission to the NNU (R-2 = 0.24, p < 0.0001) and serious adverse neonatal outcome (R-2 = 0.10, p < 0.0001), maternal Hb is an independent predictor with a linear and quadratic relationship, respectively. Therefore, both increased and decreased maternal Hb levels increase the risk of serious neonatal complications. Conclusions: Raised Hb at 27-29 weeks gestation is associated with FGR and with an increased risk of admission to the NNU and adverse fetal outcome. (C) 2015 International Society for the Study of Hypertension in Pregnancy. Published by Elsevier B.V. All rights reserved.