maternal physiological adaptations to pregnancy

summarise pregnancy hormones

• placental prolactin

• placental lactogens

• corticotropin releasing hormone

• aldosterone

• erythropoietin

summarise anatomical changes during pregnancy

• uterine enlargement

• hypertrophy of uterine musculature

• diaphragm displace cranially by gravid uterus

• apex of heart moved to anterior and to left

• left ventricular hypertrophy

• changes in calcium conc

• weight gain

how does pregnancy affect blood volume

increased blood volume→ 40 % by full term

how does pregnancy affect red cell mass

increases linearly→ 30%

how does pregnancy affect haematocrit and haemoglobin? what’s an advantage of this

decrease in both

→ plasma volume increases more than cell mass

• decreased viscosity leads to reduced resistance in flow= better placental perfusion

mechanism of hormonal stimulation in pregnancy in CVS

• stimulation of RAAS

• aldosterone= sodium ion and water retention= increased plasma volume

• increased renal erythropoietin = increases red cell mass

what supplement will restore Hb levels in pregnancy

• iron and folic acid

how is peripheral vascular resistance affected in pregnancy

reduced by 40% in mid-pregnancy→ increases after to full term

how does pregnancy affect cardiac output

• increased blood volume- more blood enters heart

• decreased peripheral resistance= reduced afterload

• increases stroke volume= increased maternal heart rate= increased cardiac output (CO= SV x HR)

describe aortocaval compression during pregnancy

• enlarged uterus= IVC and abdominal aorta compressed

• compression of IVC= decreased venous return to heart= decreased BP

• compression of aorta= reduced uteroplacental and renal blood flow