Flashcards in Repro 8.2 Maternal Physiology Adaptations in Pregnancy Deck (61)
What problems are commonly associated with pregnancy?
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?
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
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?
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:
Stasis in the biliary tract
Increased risk of pancreatitis
What makes pregnancy prothromobtic?
Fibrin deposition at the implantation site
Increased fibrinogen and clotting factors
Stasis and venodilation also contribute