Physiological Changes in Pregnancy

Key points

• • The blood volume rises greatly, and because the watery part rises more than the red cells, the haemoglobin appears diluted (physiological anaemia).
• • The heart pumps out more blood each minute, the resting pulse rises, and blood pressure tends to fall a little in mid-pregnancy.
• • Breathing deepens so that more air is moved, helping to supply the baby and clear its carbon dioxide.
• • The kidneys filter more, and the ureters widen, which makes urinary infection more likely.
• • Hormones relax smooth muscle and ligaments, slowing the gut (causing constipation and heartburn) and loosening the pelvic joints.