3. Physiology
        3.8. Maternal and foetal
            3.8.2. Maternal
3.8.2.1. Cardiovascular changes in pregnancy

Cardiovascular changes in pregnancy

[Ref: PK1:p346-368]

Haemodynamics

Heart rate

 

Stroke volume

 

Total peripheral vascular resistance

Cardiac output

NB:

According to [KB2:p248], cardiac output increases by 30% only

Causes of cardiac output increase

Blood pressure

 

Others

Central venous pressure and pulmonary capillary wedge pressure
--> Unchanged

Oncotic pressure falls by 14%
--> Predisposition to oedema

 

Blood flow and volume

Blood flow changes

Aortocaval compression syndrome

Maternal blood volume

Near term

Thus

NB:

According to [KB2:p248],
* Blood volume increase by 40-45%
* Plasma volume increase by 50%
* RBC volume increase by 30%
* Most of the increase occurs in the first 2 trimester

 

Labour

During labour, each uterine contraction squeezes about 300mL of blood into the central maternal circulation

During labour, cardiac output:

 

Maternal systolic and diastolic arterial BP increase by 10-20mmHg during uterine contraction

After delivery

Cardiac output and BP returns to non-pregnant level by 2 weeks after delivery

 

Other notes

Placenta blood flow is passive and pressure-dependent (not autoregulated)

 

 

 



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