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

•Raised haemoglobin at 27-29 weeks gestation is associated with fetal growth restriction.•Hemoconcentration is related to increased admission to NNU and adverse fetal outcome.•Maternal haemorheology parameters show potential in screening for FGR.

ObjectiveTo examine the relationship between maternal haemoglobin concentration (Hb) at 27-29 weeks' gestation and fetal growth restriction (FGR).DesignThis was a retrospective, case control study.SettingA University hospital in London, UK.PopulationPregnant women attending for routine antenatal care at 27-29 weeks of pregnancy.MethodsMaternal 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 measuresBirthweight z-score, admission to the Neonatal Unit (NNU) and adverse perinatal outcome.ResultsIncreased Hb at 27-29 weeks gestation is associated with reduced birthweight, with an inverse relationship between maternal Hb and fetal birthweight z-score (R2 = 0.10, p < 0.0001). In addition, for the prediction of admission to the NNU (R2 = 0.24, p < 0.0001) and serious adverse neonatal outcome (R2 = 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.ConclusionsRaised Hb at 27-29 weeks gestation is associated with FGR and with an increased risk of admission to the NNU and adverse fetal outcome.