• Cardiac Output – cardiac output Ý (mirrors volume expansion), plateaus at 40-50% above baseline
• stroke volume is responsible for initial increase (5-10 ml Þ 70-75ml/ stroke), then ß when heart rate Ý
• heart rate increases throughout pregnancy (15-20bts/min at 32 wks)
• During Labor – Ý cardiac output 30% (no vasoconstriction); ß systemic venous return; Ý uterine blood flow (from 2-3% to 17% of cardiac output)
• Arterial BP – ß progressively due to ß peripheral vascular resistance during 1^st 24 wks (progesterone Þ relax smooth musc.)
• systolic: ß 5-10mmHg; diastolic: ß 10-15mmHg Þ so also slight Ý in pulse pressure; central venous pressure unchanged
• returns to normal after 24 wks
• Position effects – minimal until fundus reaches Inferior Vena Cava (IVC)
• supine – ß stroke volume and cardiac output by 25% (compression on IVC ß venous return Þ ß CO) Þ hypotension
• also, 20% ß in uterine perfusion (vasoconstriction because of Ý O₂ need of brain)
• left lateral tilt – maximizes cardiac output and perfusion
• Cardiac Stressors – Ý basal metabolic rate, heart rate, contractility, pre-load, Ý left ventricular end diastolic volume
• may have tricuspid regurgitation and murmers (due to thickening of valves)
• Cardiac Protectors – ß systemic venous return (afterload) and minimal Ý in pO₂
• Cardiac Test Changes – sinus tachycardia (P-R interval ß ), supraventricular arrythmias, valve regurgitation, mild LVH

• Volume expansion–mother loses 500cc of blood to perfuse fetal compartment; compensated by maternal vol. expansion
• Mechanism – hormonal-mediated vasodilation (progesterone and estrogen), Ý vascular capacity and ß pressure in uterine bed, renal salt and water retention (via estrogen’s effect on renin-AG-aldo axis), Ý sensation of thirst
• begins by week 6, peaks during early 3^rd trimester at 6-8 liters (30-45% above baseline)
• Manifestations–postural fainting, varicose veins, wt gain, anemia, Ý thirst/urination, slow development of shock and fever, loss of RBC’s
• Compounding factors – maternal weight, vascular disease, size and number of fetuses
• Erythrocytes – RBC mass Ý 25%, ß viscosity (placental chorionic somatommotropin, progesterone, prolactin)
• Edema – ß colloid osmotic pressure, Ý "third spacing" (less osmotic pressure to hold fluid in results in diluted proteins)
• Pulmonary edema – ß osmotic gradient in lungs relative to Pulmonary Capillary Wedge Pressure
• Leukocytes and platelets – WBC’s Ý during pregnancy (Ý neutrophils), progressive ß in platelets
• Coagulation – pregnancy is a hypercoagulable state
• nearly all clotting factors Ý (exceptions: prothrombin (II), V, and XII are unchanged; XI, XIII, antithrombin III decrease)

Pulmonary – oxygen requirement Ý by 40-60%

• Lung volume and Pulmonary Excursion – 30-40% Ý in tidal volume due to ß expiratory reserve volume (ß dead space) from Ý rib cage volume displacement (mechanical change:Ý subcostal angle, chest diameter, diaphragm elevation)
• Ý minute ventilation (30-40%); vital capacity, inspiratory reserve volume, and respiratory rate remain unchaged
• Upper respiratory tract – Mucosa of nasopharynx becomes hyperemic and edematous (estrogen)
• leads to nasal stuffiness and epistaxis (Ý mucous production)
• Oxygen transport – Ý 2,3 DPG causes ß maternal O₂ affinity allowing greater O₂ for fetus (fetus Hb also binds O₂ better)
• Maternal Adaptations – Ý mouth breathing, drying, dyspnea, nosebleeds, Ý diphragmatic excursion

• Anatomic changes – kidneys enlarge (Ý renal vasculature and interstitial volume, right>left); dilation of ureters and renal pelvis (mechanical compression of the ureters by uterus and ovarian veins and progesterone induced muscle relaxation)
• Clinical Manifestations – urinary incontinence from Ý pressure, Ý stones and bacterial infections (stress reflux)
• Hemodynamics – Ý effective renal plasma flow (ERPF) by 75% (840ml-min), Ý GFR (50%) due to Ý creatinine clearance and ß plasma osmolality (fall in serum Na⁺ and anions)
• Salt and water metabolism – Ý in Na⁺, Cl^-, and water resorption (Ý renin, angio, aldo, estrogen, deoxycorticosterone)
• Ý Atrial natriuretic peptide – Ý stretch on atrium from Ý plasma volume

GI – Ý appetite, Ý saliva, ß stomach tone and motility (Ý GERD), ß bowel motility due to progesterone (leads to constipation)

Liver – Ý alk phos, Ý cholesterol and protein production. Unchanged bilirubin, AST, ALT, and PT time

Musculoskeletal – edema, varicosities, hemorrhoids, carpel tunnel, erythema, acne, hirsuitism

Endocrinological – Ý prolactin, oxytocin ACTH, thyroxine, estrogen, CRH; ß FSH, LH, growth hormone