Effect of maternal parity and infant sex upon the haematological values of cord blood.

Coulter Counter (Model S) analysis of 400 cord blood samples are presented, together with differential white cell counts for 249 of these. The mean values for haemoglobin and red cell count are somewhat higher than previous values determined by manual methods, while those for haematocrit and mean cell volume are slightly lower. An unexpected finding was that the red cell count, haemoglobin concentration, and haematocrit, are significantly higher in male than in female infants. A parity effect was also demonstrated: infants of both sexes born as second or subsequent births had lower values for total white cell count, haemoglobin concentration and haematocrit, than first-born infants.