Pregnancy Physiology Flashcards

1
Q

What happens to the cardiovascular system during pregnancy?

A

SV up 30%, HR up 15% & cardiac output up 40%

systolic BP is unaltered

diastolic BP is reduced in the 1st and 2nd trimester, returning to non-pregnant levels by term

enlarged uterus may interfere with venous return which can lead to ankle oedema, supine hypotension and varicose veins

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2
Q

What happens to the pulmonary system during pregnancy?

A

Pulmonary ventilation up by 40%, tidal volume from 500 - 700ml (due to effect of progesterone on respiratory centre)

Oxygen requirements increase by only 20%, therefore over breathing leads to a fall in pCO2 - this can give rise to a sense of dyspnoea that may be accentuated by elevation of the diaphragm

BMR up 15% - this may be due to increased thyroxine and adrenocortical hormones - women may hence find warm conditions uncomfortable

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3
Q

What are the changes to the blood in pregnancy?

A

Maternal blood volume up 30%, mostly in 2nd half - red cells up 20% but plasma up 50% Hb falls

Low grade increase in coagulant activity

rise in fibrinogen and Factors VII, VIII, X, also an increase in cholesterol

fibrinolytic activity is decreased - returns to normal after delivery (placental suppression?)

prepares the mother for placental delivery

leads to increased risk of thromboembolism

Platelet count falls

WCC & ESR rise

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4
Q

What are changes in the urinary system in pregnancy?

A

blood flow increase by 30%

GFR increases by 30-60%

Salt and water reabsorption is increased by elevated sex steroid levels

Urinary protein losses increase

Urea and creatinine levels are decreased

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5
Q

What are the biochemical changes assocaited with pregnancy?

A

Calcium requirements increase during pregnancy

especially during 3rd trimester + continues into lactation

calcium is transported actively across the placenta

serum levels of calcium and phosphate actually fall (with fall in protein)

ionised levels of calcium remain stable

Gut absorption of calcium increases substantially - due to increased 1,25 dihydroxy vitamin D

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6
Q

What are liver changes in pregnancy?

A

Unlike renal and uterine blood flow, hepatic blood flow doesn’t change

ALP raised 50%

Albumin levels fall

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7
Q

What are changes of the uterus during pregnancy

A

100g → 1100g

hyperplasia → hypertrophy later

increase in cervical ectropion & discharge

Braxton-Hicks: non-painful ‘practice contractions’ late in pregnancy (>30 wks)

retroversion may lead to retention (12-16 wks), usually self corrects

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