5. Effect of Pregnancy on Maternal Physiology Flashcards
Increase in metabolic demands on the mother are met by….
hormone driven physiological adaptation
At term the uterus reaches?
The level of the xyphoid process
What happens to structures on post abdominal wall during pregnancy?
Compressed when lying down
Change to centre of gravity result in what during pregnancy?
Development of accentuated lumbar lordosis
==> Backache
Result of relaxin release during pregnancy?
Softening of ligaments.
–> Sacroiliac and symphysis pubis pain
Anatomical changes to mother during pregnancy?
- Fist sized organ grows to occupy most of the pelvis by 16 weeks, palpable abdominally from 13 weeks.
- At term uterus reaches the level of the xyphoid process (thorax widens as the ribs flare to accommodate organs).
- Compression of structures on the posterior abdominal wall especially when lying down.
- Changes centre of gravity develop an accentuated lumbar lordosis. Leads to –> Backache.
- Relaxin causes softening of ligaments. Leads to–> Sacroiliac and symphysis pubis pain
- Weight gain averages 12.5kg.
Cause for 12.5kg weight gain?
6kg uterus, foetus and breast
3kg fat reserve for lactation
Remainder is fluid
Result for pressure on IVC from foetus?
Impedes venous return from LL
Impairs function of valves results in varicose veins
Cause for physiological anaemia is pregnancy?
Haematopoiesis is increased up to 30%
BUT
Increase in plasma volume (up to 50%) means that RBC count, haematocrit and haemoglobin conc are all reduced
Changes to WBC, platelets count and clotting factors during pregnancy?
- Small increase in WBC.
- Unchanged platelet count, but more reactive.
- Increase in clotting factors with thromboembolism risk.
Circulatory adaptations to TPR during pregnancy?
Uteroplacental circulation is characterised by high volume, low resistance flow
- Due to uterine spiral arteries and arterioles inability to vasoconstrict
Pregnancy hormones = Reduce sensitivity to pressor agents (e.g. angiotensin) to vasoconstrict. Hence peripheral vasodilation occurs and TPR reduces.
Result of peripheral vasodilation in pregnancy women?
Heat intolerance
Consequence of reduced TPR is pregnant women on RAAS?
Triggers RAAS and low blood pressure in vessels is detected.
This leads to increased blood volume.
Effect of oestrogen in maintaining normal blood pressure in foetus?
Oestrogen increases vascular endothelial growth factor and NO production in endothelial cells
What does VEGF mean?
Vascular endothelial growth factor
What do endothelial cell release in order to help maintain the low bp in the foetus?
Prostacyclin (prostaglandin I2 or PGI2)
Summary of changes to mother?
Anatomical changes
Circulatory adaptations: Blood volume, blood composition, TPR reduces, CO, bp, pre-eclampsia, eclampsia
Respiratory changes
Renal changes
Changes to CO during weeks 8-28 of pregnancy?
Increases by 30-50%
By..
-Increase in HR to 80-90/min
-Increase SV by about 10%
Which organs receive increased blood flow during pregnancy?
Uterus, breast and skin