maternal adaptations of pregnancy

name some cardiovascular changes in pregnancy

(increases and decreases)

increase in:

• cardiac output

• heart rate

• oxygen consumption

• blood flow to uterus, kidneys and brain

• blood volume

• sympathetic tone

decrease in:

• systolic + diastolic BP

• mean arterial pressure

• colloid osmotic pressure

• vagal tone

blood volume expansion

• what pregnancy hormone is responsible for the synthesis of the other hormone responsible for this

• the receptor for this is upregulated where in the body

• what pregnancy hormone counterbalances vasoconstriction

• what happens to RBCs

Blood volume expansion  

• Driven by oestrogen-stimulated hepatic synthesis of angiotensinogen  

  • Activates RAAS system  

  • Aldosterone increases sodium and water retention  

  • Plasma volume increases before red cell mass expands  

  • Oestrogen increases angiotensin II receptor density on vascular smooth muscle  

• PG counterbalances vasoconstriction  

• Reduces Ca influx into smooth muscle cells -> net vasodilation  

• RBC mass increases by erythropoietin upregulation, slowly  

• Expands preload -> ^SV  

cardiac output increase

• what happens to stroke volume in early pregnancy

• what physiological effect does relaxin have on BVs

• how does the placenta reduce afterload

• why does it do this

Cardiac output increases  

• Early pregnancy: ^^ SV  

• Mid-late pregnancy: ^^ HR (10 bpm) 

  • Sympathetic activation and reduced baroreceptor sensitivity  

• Relaxin  

  • Enhances NO signalling to increase arterial compliance  

• OE + relaxin 

  • NO synthase expression ^ in endothelial cells -> systemic vasodilation  

• Placenta acts as a low resistance vascular bed, reducing afterload  

• Ensures enough uteroplacental perfusion 

drop in vascular resistance

• what does PG do

• what does relaxin do

• what happens to blood pressure in early pregnancy

PG  

• Smooth muscle relaxation  

• Reduces MLCK activity  

Relaxin  

• Increase VEGF and matrix metalloproteinases 

• Softens connective tissue in vessel walls  

BP falls in early pregnancy  

respiratory changes

• what happens to the physical position of the diaphragm, ribs, subcostal angle and ligaments

• what happens to tidal volume, inspiratory capacity, expiratory reserve, residual volume and functional residual capacity

• what happens to total lung capacity and inspiratory reserve volume

Mechanical changes  

• Elevation of diaphragm  

• Robs flare 

• Subcostal angle increases  

• Ligaments relax  

Changes in lung function  

• ^^ tidal volume  

• ^^ inspiratory capacity  

• -- expiratory reserve volume  

• -- residual volume and functional residual capacity  

Total lung capacity, vital capacity, inspiratory reserve volume doesnt change much  

increased ventilation

• what hormone increased tidal volume

• what is its effect on CO2

• why is this needed (gradient established)

PG acts as a respiratory stimulant at medullary centre  

• TV ^^ 

• Resp rate stays similar  

PG ^^ central chemoreceptor sensitivity to CO2  

• Leads to chronic respiratory alkalosis (PaCO2- 30mmHg) 

Enhances foetal CO2 clearance (F-> M gradient) 

diaphragm elevation

• due to this what happens to functional residual capacity and residual volume

• what hormone soften the costochondral ligaments

• what is the pregnancy symptom for this

Uterine enlargement elevates diaphragm by 4-5 cm  

• Reduces FRC (functional residual capacity) and RV (residual volume) 

• Ribcage widens (OE-mediated ligament laxity) 

• Relaxin: costochondral ligaments soften  

• Inspiratory capacity preserved despite reduced residual volume  

• Breathlessness is common  

renal changes

• how does PG, relaxin and NO increase renal plasma flow

• what happens to renal vascular resistance and cardiac output

• increased GFR

  • what happens to creatinine clearance, urea

Renal plasma flow ^^ 50-80% 

• Systemic vasodilation (PG, relaxin, NO) 

• Reduced renal vascular resistance  

• Increased cardiac output  

Increased GFR 50% (glomerular filtration rate) 

• Creatinine clearance increases  

• Serum creatinine and urea falls  

• Glomerular barrier remain intact  

tubular reabsorption

• what hormone increases Na+ reabsorption

• what is the effect on plasma volume because of this

• what happens to glucose and amino acid reabsorption

• why is bicarbonate secreted more (blood)

Sodium  

• Increased aldosterone -> increased Na+ reabsorption  

• Sodium retention -> supports plasma volume expansion  

Glucose and amino acids  

• Increased filtered load exceeds reabsorption capacity  

• Glycosuria, aminoaciduria  

Bicarbonate  

• Kidneys secrete more HCO3- to compensate for respiratory alkalosis  

• Leads to lower serum bicarbonate  

fluid retention

• what system is activated

• increases sensitivity to what hormone

ureteric dilation

• what hormone relaxes smooth muscle in the bladder

• how does urinary stasis happen

Fluid retention  

• RAAS activation (renin-angiotensin-aldosterone system)

• Increased antidiuretic hormone ADH sensitivity  

Ureteric dilation  

• PG helps relax smooth muscle  

• Mechanical compression by uterus  

• Reduced peristalsis -> urinary stasis  

• > increased UTI risk  

renal changes summary: affect on

• ureters

• bladder tone

• renal plasma flow

• GFR

• sodium reabsorption

• serum urea and creatinine levels

• dilation

• decreased tone

• increase plasma flow

• increase GFR and glucose excretion

• increase

• decrease in serum levels

GIT changes

• mouth

• oesophagus

• stomach

• intestines

• caecum/appendix

• gallbladder

• liver

Mouth  

• More susceptible to gingivitis, caries  

Oesophagus  

• Relaxation of oesophageal sphincters  

Stomach  

• Decreased gastric tone and motility  

Intestines  

• Decreased gut motility – constipation  

Displaced caecum and appendix  

• Attention to site of pain in appendicitis – McBurneys point 

Gallbladder  

• Decreased tone and motility  

Liver  

• Alters production of liver enzymes, proteins, altered position  

endocrine changes

• OE/PG levels

• what hormone is secreted once embryo implants

• what increases milk production

• PTHrP levels

• ^^ OE PG 

• HCG  

• Increased prolactin (pituitary enlarges by 50%) 

• Parathyroid hormone increased  

insulin sensitivity

• what happens to this

• why

• INSULIN RESISTANCE

• Ensures glucose is diverted to foetus  

• Encourages mother to use fatty acids for her own energy  

HPL

• what does it stand for

• increases the lysis of which energy store

• effect on maternal glucose uptake

• human placental lactogen

• lipolysis - free fatty acids inhibit insulin signalling

• reduces maternal glucose uptake

progesterone

• effect on maternal fat deposition in early pregnancy

• effect on insulin sensitivity

• effect on metabolic activity

• promotes maternal fat deposition

• increases insulin resistance

• supports shift towards fat use

placental TNF-a

• effect on insulin signalling

• effect on GLUT-4 translocation

• metabolism

• impairs insulin receptor signalling

• reduced glucose translocation

• increases lipolysis

cortisol

• gluconeogenesis

• peripheral glucose uptake

• insulin resistance

• increase

• decrease

• increase

prolactin

• effect on B-cell mass

• effect on insulin secretion

• expands B-cell mass

• increases insulin secretion

oestrogen

• effect on lipogenesis

• effect on hepatic glucose output

• enhances lipogenesis

• increases hepatic glucose output

thyroid

• increase or decrease in T3,T4 (metabolism regulators)

• change in iodine requirements

  • it is important for the development of what in the foetus

• increase in T3/4

• increase in iodine requirement

  • important for foetal neurodevelopment

adrenal gland

• what hormone stimulates ACTH hormone

  • what happens to cortisol levels

• aldosterone increase

  • sodium levels

  • what happens to BP

Placental and maternal corticotropin releasing hormone CRH stimulates maternal ACTH  

• Cortisol ^^ 2/3x  

Aldosterone increases  

• Sodium retention  

• Despite high aldosterone, BP falls due to systemic vasodilation  

• Explains cushingoid appearance and fluid retention in pregnancy  

MSK, sensory, neural system changes

• increased strain on body bc of what spine shape change

• weight change

• blood flow to ENT, airways

• Change in posture/gait  

• Increased strain bc of lordosis  

• Altered sleep pattern  

• ENT - ^ vascularity, oedema  

• Airway - ^ mucosal oedema  

• Eyes – corneal oedema, -- ocular pressure  

• 11kg weight gain  

haematological changes

• plasma volume

• red cell mass

• WCC

• iron binding capacity and rquirement

• coagulation state

• platelet and HB count

• colloid osmotic pressure

• Plasma volume increases by 50% 

• Red cell mass increases  

• WCC increases  

• Reticulocyte count increases  

• Increase in iron binding capacity, and increase in iron requirement  

• Hypercoagulable state – fibrinogen and FVII, VIII, X, vWF and ristocetin co-factor activity increased  

• Decrease platelet count  

• Decrease in haemoglobin (physiologic anaemia) 

• Total protein decrease (reduce colloid osmotic pressure-oedema, drug absorption) 

• Decrease in osmolality (ADH reset) 

hyoercoagulability

• what hormone synthesises clotting factors

• protein S count

• fibrinolysis

• platelet count

OE increases hepatic synthesis of clotting factors  

• Clotting cascade becomes primed – clots form faster and more robustly  

Protein S decreases  

• System cant stop clot formation once it starts  

Fibrinolysis is suppressed  

• Clots persist longer and are harder to dissolve  

Platelet count decreased  

• Dilutional effect from plasma volume expansion  

immune system changes

• why is there a shift from Th1→Th2 immune response

• which 4 pregnancy hormones suppress immune system

• what happens to WCC

• chemotaxis are reduced - why

• what happens to IgG,A,M

• Cell mediated immunity is reduced and complement system c1, c1a, B, D are reduced  

Shift from Th1-> Th2  

• Protects foetus from rejection  

• OE, PG, hCG, HPL – suppress immune system  

• WCC ^^ 

• Chemotaxis are reduced – prevents excess inflammation  

• Ig G, A, M decrease