PATRICK DUFF, M.D. UNIVERSITY OF FLORIDA MATERNAL PHYSIOLOGY PATRICK DUFF, M.D. UNIVERSITY OF FLORIDA

MATERNAL PHYSIOLOGY OVERVIEW Placenta Hormone production Mechanisms of placental transfer Changes in uterus Cardiopulmonary changes Hematologic changes Alterations in GI function Renal function changes

PLACENTAL HORMONE PRODUCTION

HORMONE PRODUCTION BY THE PLACENTA FUNCTION Human placental lactogen (HPL) Antagonizes insulin  spares glucose for use by fetus Enhances lipolysis provides alternate fuel source for mother Human chorionic gonadotropin (hCG) Stimulates corpus luteum to secrete estradiol and progesterone

MECHANISMS OF PLACENTAL TRANSFER EXAMPLES Simple diffusion Water, oxygen, carbon dioxide Facilitated diffusion Glucose Active transport Amino acids, iron Pinocytosis Drugs, immunoglobulins

CHANGES IN UTERUS Uterine blood flow increases significantly Uterine blood flow may approach 500 – 750 cc/ minute Hemorrhage is key cause of maternal death Status % of C.O. Perfusing Uterus Non-pregnant < 1 % Pregnant 15-20%

DISTRIBUTION OF UTERINE BLOOD FLOW DURING PREGNANCY

CARDIOVASCULAR CHANGES DURING PREGNANCY CARDIAC FUNCTION PERCENT INCREASE IN PREGNANCY Heart rate 5-15% Stroke volume 25-30% Cardiac output 35-50%

CHANGES IN CARDIAC OUTPUT DURING LABOR STAGE OF LABOR ADDITIONAL PERCENT INCREASE IN CARDIAC OUTPUT Early first 15-20% Late first 30-35% Second 35-40%

DANGEROUS CARDIAC DISEASES IN PREGNANCY Stenotic valve lesions Ischemic heart disease Marfan syndrome Eisenmenger’s syndrome Primary pulmonary hypertension

PULMONARY FUNCTION ALTERATIONS IN PREGNANCY

PULMONARY FUNCTON ALTERATIONS IN PREGNANCY PULMONARY VOLUME CHANGE Inspiratory reserve volume No change Tidal volume Increased Expiratory reserve volume Decreased Residual volume

PULMONARY FUNCTION ALTERATIONS IN PREGNANCY PULMONARY CAPACITY CHANGE Inspiratory capacity (IRV + TV) Increased Vital capacity (IRV + TV + ERV) Unchanged Functional residual capacity (ERV + RV) Decreased Total lung capacity (IRV+TV+ERV+RV)

ALTERATIONS IN ARTERIAL BLOOD GASES Increased pH Decreased pCO2 Decreased HCO3 PARTIALLY COMPENSATED RESPIRATORY ALKALOSIS

HEMATOLOGIC ALTERATIONS IN PREGNANCY COMPONENT PERCENT CHANGE Blood volume 30-50% Plasma volume 50% Red cell number 30%

PRINCIPAL CAUSES OF ANEMIA IN PREGNANCY ETIOLOGY KEY DIAGNOSTIC TEST(S) Iron deficiency RBC indices, serum ferritin Hemodilution RBC indices Folate deficiency RBC indices, serum folate B 12 deficiency Hemoglobinopathy Hgb electrophoresis

PERIPHERAL BLOOD SMEARS

HEMATOLOGIC ALTERATIONS IN PREGNANCY CELL LINE CHANGE White blood cells Slight increase Platelets* Unchanged to slight decease * Most common causes of thrombocytopenia – pre-eclampsia and gestational thrombocytopenia

COAGULATION CHANGES IN PREGNANCY Enhanced hepatic synthesis of I, II, VII, VIII, IX, and X Placenta  III (tissue thromboplastin) Platelets  aggregate more readily

VIRCHOW’S TRIAD THROMBOSIS Venous stasis Alteration in venous wall Hyper-coagulable state

GASTROINTESTINAL ALTERATIONS IN PREGNANCY CLINICAL CONSEQUENCE Delayed gastric emptying (gastroparesis) GERD Early satiety Biliary duct stasis Cholelithiasis pancreatitis Change in location of appendix Delay in diagnosis

CHANGE IN ANATOMIC LOCATION OF APPENDIX IN PREGNANCY

GASTROINTESTINAL ALTERATIONS IN PREGNANCY CONSEQUENCE Increased intra-abdominal pressure Hiatal hernia Delayed colonic empyting Constipation

RENAL FUNCTION ALTERATIONS IN PREGNANCY Renal blood flow increases 30 – 40 % above pre-pregnancy levels GFR ( creatinine clearance) increases Serum BUN, creatinine, and uric acid decrease

FREQUENCY OF UTIs IN PREGNANCY TYPE OF INFECTION FREQUENCY Asymptomatic bacteriuria 5-10% Acute cystitis 2-3% Pyelonephritis 1-2%

MICROBIOLOGY OF UTIs IN PREGNANCY

INCREASED RISK OF PYELONEPHRITIS IN PREGNANCY Progesterone inhibits ureteral peristalsis Mechanical compression of ureter by gravid uterus Complications of pyelonephritis Preterm labor Sepsis and ARDS

INCREASED RISK OF NEPHROLITHIASIS Increased concentration of calcium in the urine Urinary stasis Most common stones Calcium oxalate Struvite

MATERNAL PHYSIOLOGY SUMMARY ORGAN SYSTEM KEY TEACHING POINTS Cardiac Danger of stenotic lesions and pulmonary hypertension Pulmonary VC – unchanged FRC – decreased ABGs – compensated respiratory alkalosis

MATERNAL PHYSIOLOGY SUMMARY ORGAN SYSTEM KEY TEACHING POINTS Hematologic Increased frequency of anemia, DVT, PE GI Increased frequency of GERD, gall bladder disease, and constipation Renal Increased RBF and GFR Increased risk of ascending UTI Increased risk of nephrolithiasis