Women during pregnancy or preconception (148 studies, n= 13,839,327).
Updated systematic review on low (< 110 g/L) and high (≥ 130 g/L) maternal haemoglobin (Hb) concentrations and associations with adverse maternal and infant health outcomes.
Low maternal Hb at any time point in pregnancy was associated with: Low birthweight, very low birthweight (VLBW), preterm birth (PTB), small-for-gestational age (SGA), stillbirth, perinatal mortality, neonatal mortality, postpartum haemorrhage, transfusion, pre-eclampsia, and prenatal depression. For maternal mortality, the OR was higher for Hb < 90 (OR, 4.83; 95% CI [2.17, 10.74]) than for Hb < 100 (OR, 2.87; 95% CI [1.08, 7.67]). High maternal Hb was associated with: VLBW, PTB, SGA, stillbirth, maternal mortality, gestational diabetes, and pre-eclampsia. Stronger associations were noted earlier in pregnancy for low Hb and adverse birth outcomes while the role of timing of high Hb was inconsistent.