Umbilical Cord Blood Hemogram: What Is the Effect of Maternal Anemia?

Introduction: Umbilical cord blood (UCB), a source of hematopoietic stem cells, represents neonatal blood and reflects the health of the newborn to a great extent. Establishing biological reference intervals is essential to discard samples before submitting for expensive investigations and storage. Also neonatal anemia has to be recognised early. Hence this study is undertaken to establish a biological reference interval for the UCB hemogram and to study the effect of maternal anemia on the fetus.

Materials and methods: This is a prospective study conducted in two steps after Institutional Ethics Committee approval. In each step, 100 full term infants with normal birth weight and APGAR score delivered by spontaneous vaginal delivery were enrolled. In the first step, the mothers had hemoglobin (Hb) above 12 g/dL and no co-morbid conditions. In the second step, maternal hemoglobin cut offs of 12 g/dL and 10.9 g/dL were established. UCB was collected after clamping the cord in a K₂-EDTA evacuated tube. The blood was processed in Beckman Coulter LH 780 hematology analyzer. Delta check and manual count of RBC precursors was done by peripheral smear and reticulocyte count. Data was analysed using SPSS IBM statistics software version 19.

The RBC parameters (RBC count, Hb, packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), red cell distribution width (RDW)) and RBC precursors between groups were compared. The changes according to the grade of anemia were analysed and compared with the biological reference interval. The maternal Hb was grouped in 1 g/dL differences and the Hb in the UCB of the respective neonates was correlated.

Results: The biological reference interval for UCB hemogram was established.

No significant difference was found in the RBC parameters in the UCB of neonates born to anemic and non-anemic mothers. Reticulocyte parameters namely reticulocyte count, absolute reticulocyte count, reticulocyte index and reticulocyte proliferation index showed significant increase in the UCB of neonates born to anemic mothers. No significant difference was found in the nucleated RBC (nRBC) count between the groups. When compared to the biological reference interval, MCH and MCHC were lower and reticulocyte parameters were higher in the UCB of neonates born to anemic mothers. A significant positive Pearson correlation was found between cord blood Hb and maternal Hb.

Discussion: Through the UCB Hb correlated positively with maternal Hb, it has been found that maternal anemia does not cause fetal anemia. This may be due to high iron transfer from mother to fetus and maximally stimulated erythropoiesis at the end of gestation.

However, significantly low MCH and MCHC values were seen in the UCB of neonates born to anemic mothers in comparison with the biological reference interval. This may be due to early decreased hemoglobin content within the cell which is compensated by the high RBC count. This is further confirmed by the significant elevation of reticulocyte parameters in the UCB of neonates born to anemic mothers.

Conclusion: Maternal anemia depending on the severity causes chronic hypoxia so that the fetal bone marrow reacts to the effect of erythropoietin by increased erythropoiesis and RBC precursor release. Severe maternal anemia may cause neonatal anemia which needs further ferrokinetic studies. Maternal anemia in developing countries needs to be corrected. Also the biological reference interval established serves as a tool for neonatologists, transplant hematologists and future studies in UCB.