Repro 8.2 Maternal Physiology Adaptations in Pregnancy Flashcards Preview

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Flashcards in Repro 8.2 Maternal Physiology Adaptations in Pregnancy Deck (61)
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What problems are commonly associated with pregnancy?

Gestational diabetes
Hypertensive disorders


What tests are done in antenateal screening?

History and examination for risk factors
Blood tests - blood group, haemoglobin, infection
Urinalysis - protein


What cardiovascular changes occur with pregnancy?

Increased blood volume -> relationship with cardiac output and stroke volume and heart rate so they all also increase
Systemic vascular resistance decreases
Blood pressure initially decreases but returns to normal by T3


Why does BP initially decrease in pregnancy?

Progesterone effects on smooth muscle decrease resistance


Why does BP return to normal in T3?

Aortocaval compression by gravid uterus


Why is endothelium important in pregnancy?

Controls vascular permeability and contributes to the control of vascular tone


What is pre-eclampsia?

Defect in placentation, poor ureteroplacental circulation and widespread endothelial dysfunction
Vasoconstriction and plasma-contraction


What changes occur in the urinary system in pregnancy?

Glomerular filtration rate increases
Renal plasma flow increases
Filtration capacity intact
Functional renal reserve decreases as GFR increases


What effects do the renal changes have on serum concentrations of waste materials?

Increased GFR decreases serum concentrations of urea, uric acid, bicarbonate and creatinine


What are the normal pregnancy ranges for urea and creatinine?

Urea - 3.1mmol/L (decrease by 50%)
Creatinine - 25-75micromol/L


What complications might arise due to changes in the urinary system?

Urinary stasis - progesterone effect on urinary collecting system -> hydroureter or from obstruction
Increased risk of UTI (pyelonephritis may cause requirement of pre-term labour


What anatomical changes in the respiratory system result?

Diaphragm displaced
A-P and transverse diameters of thorax increase
Intercostal angle widens
(mechanical limitations from uterus)
Physiological change also occur


What are the consequences of changes in the resp system?

Decreased functional residual capacity
Vital capacity and total lung capacity relatively unchanged
Increased minute and alveolar ventilation
Increased tidal volume
RR unchanged


Why do many women experience physiological hyperventilation during pregnancy?

Increased metabolic CO2 production
Increased resp drive effect of progesterone
Resulting in resp alkalosis compensated by increased renal bicarbonate excretion and changes in sensitising chemoreceptors to CO2 changes


What causes the physiological dyspnoea in pregnancy?

Progesterone-drivne hyperventilation


At what stage of pregnancy does functional residual capacity change?

At T3 it decreases


How does carbohydrate metabolism change during pregnancy?

Pregnancy increases maternal peripheral insulin resistance - switches to gluconeogenesis and alternative fuels
This is achieved by human placental lactogen (hPL) also by prolactin, oestrogen/progesterone and cortisol


How does maternal blood glucose change?

Decrease in fasting blood glucose
Increase in post-prandial blood glucose


What is gestational diabetes?

Carbohydrate intolerance first recognised in pregnancy and not persisting after delivery


What risk factors are associated with poor control of gestational diabetes?

Macrosomic foetus (glucose stored as fat)
Increased rate of congenital defects (eg. foetal liver enlarges due to glycogen storage)


How is gestational diabetes tested for?

Oral glucose tolerance test


What are the risk factors for developing gestational diabetes?

Family history of type 2 diabetes
Previous gestational diabetes or pregnancy problems


How does lipid metabolism change during pregnancy?

Increase in lipolysis from T2
Increase in plasma free fatty acids on fasting (free fatty acids provide substrate for maternal metabolism, leaving glucose for the foetus


Why is pregnancy associated with an increased risk of ketoacidosis?

Blood glucose falls as the foetus uses it. Lipids are used for maternal metabolism


How does thyroid activity change during pregnancy?

Thyroid binding globulin production increased
T3 and T4 increased but free T4 is in the normal range


Why does pregnancy result in increased thyroid activity?

hCG has a direct effect on thyroid stimulating thyroid hormone production


What anatomical changes occur in the GI system in pregnancy?

Alteration in the disposition of the viscera e.g. appendix moves to RUQ as uterus enlarges


What physiological changes occur in the GIT during pregnancy?

Smooth muscle relaxation by progesterone:
Delayed emptying
Stasis in the biliary tract
Increased risk of pancreatitis


What makes pregnancy prothromobtic?

Fibrin deposition at the implantation site
Increased fibrinogen and clotting factors
Reduced fibrinolysis
Stasis and venodilation also contribute


What are the consequences and problems with pregnancy being a prothrombotic state?

Thromboembolic disease in pregnancy may result
But warfarin crosses the placenta and is teratogenic