Blood volume rises as illustrated; the increase in plasma volume
(40-50%) is greater than that of red cell volume (20-30%). There is a resulting fall in haemoglobin concentration.

11 g/dl is the lower limit of normal for haemoglobin concentration during pregnancy.

This increased blood volume enables the mother to compensate for blood loss at delivery.

White cell counts are usually around the normal limits for non-pregnant adult, until labour and delivery. During labour there are marked elevations in the white cell count.