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Notes
      3. Old stuff
          3.2. Old physio stuff (around 2005)
              3.2.3. Physiology
                  3.2.3.8. Maternal and foetal
                      3.2.3.8.2. Maternal
 3.2.3.8.2.8. CNS changes in pregnancy 

CNS changes in pregnancy

[Ref: PK1:p352]

Endorphin

The placenta produces endorphins and enkephalins
* May be analgesic during pregnancy

Endorphin production increases significantly in proportion to the frequency and duration of uterine contractions during labour and delivery
* Role unclear

Progesterone

Progesterone has sedative actions
* Increase 10-20 fold in 3rd trimester

Implication

MAC of volatile agents is reduced by 30-40% during pregnancy
* Partly because of endorphins and progesterone

 

Epidural and CSF pressure

Epidural veins are engorged

Epidural pressure are higher than in non-pregnant women
* Due to increased abdominal pressure
* May increase to 4-10cmH2O in labour, and to 60cmH2O during bearing-down efforts

 

CSF pressure is not changed at rest

May increase to 70cmH2O during bearing-down efforts

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