Physiological Changes During Pregnancy

							Physiological Changes During Pregnancy

Metabolic Changes                                                                Physiological Changes (cont.)
Placenta secretes hPL (human placental lactogen)                                 Urinary system
(also known as hCS (human chorionic somatomammotropin))                          Renal dilatation
hPL                                                                                  ↑Length, Weight of kidneys
Promotes growth of fetus                                                             Dilated – Renal pelvis, Ureters (↑urinary stasis - ↑ infection)
Exerts a maternal glucose-sparing effect                                         Hydronephrosis, Hydroureter
hCT (Human chorionic thyrotropin)                                                    ↑ Progesterone (hypotonia of smooth ms. in ureter)
↑ Maternal metabolism                                                                Enlarged ovarian vein complex (dilatation)
↑ Parathyroid hormone                                                                Dextrorotation of uterus
 +ve calcium balance                                                                 Hyperplasia of smooth ms.
                                                                                 ↑ Renal plasma flow rate
Physiological Changes                                                            ↑ GFR (but volume of urine passed is not increased)
GIT                                                                              Glucosuria (↑ GFR – impaired tubular reabsorption capacity to filter glucose)
Morning sickness (due to ↑ estrogen, progesterone)                               Proteinuria
Urinary system                                                                   ↑ Renin
↑ Urine production (handle additional fetal wastes)                              Bladder
Respiratory system                                                                   ↑ Urinary frequency (pressure from uterus)
Edematous                                                                            ↑ Bladder vascularity
Nasal congestion                                                                     ↓ Muscle tone
Dyspnea (may develop late in pregnancy)                                              ↑ Bladder capacity
CVS
                                                                                 GIT system
↑ CO (↑ Stroke volume)
                                                                                 ↓ GIT motility (due to ↑ progesterone) (constipation)
Apex beat moved laterally
                                                                                 Gastric reflux
↑ Cardiac capacity (70-80mL)(due to ↑ volume/ hypertrophy of cardiac ms.)
                                                                                 Gums hypertrophy, Vitamin C deficiency, Bleeding gums
↓ BP
                                                                                 ↑ ALP (liver)
Venous pressure
                                                                                 Reproductive
    Pressure of pregnant uterus on femoral vein, IVC
                                                                                 Goodell’s sign – softening of cervix (on pelvic exam)
     Impede blood flow from legs
                                                                                 Chadwick’s sign – purple hue of vagina, cervix
    ↑ Venous pressure
                                                                                 Hegar’s sign – compressibility, softening of isthmus
     Force fluid out – cause edema
                                                                                 Uterine hypertrophy (of myocytes)
    Distensibility of veins
                                                                                      ↓ Venous return
    Lateral recumbent position (relief pressure on femoral vein, IVC)
                                                                                      ↓ CO
Hematological system
                                                                                      ↑ TPR (to minimize fall in BP)
↑ Total plasma volume
                                                                                 Endocrine system
↑ Blood volume
                                                                                 Anti-insulin environment, aided by
    ↑ Blood flow to uterus, kidneys
                                                                                      Placental lactogen
    ↓ Serum albumin - ↓ Oncotic pressure – general edema (lower limbs)
                                                                                       Similar to GH
RBC
                                                                                       ↑ Lipolysis, FFA
    ↑ Red cell volume (but lag behind plasma volume)
                                                                                       ↑ Tissue resistance to insulin
     ↓ Hematocrit, [Hb]
                                                                                      ↑ Unbound cortisol
     Physiological anaemia of pregnancy
                                                                                      Estrogen, progesterone – exert anti-insulin effects
    Stimulate erythropoiesis – progesterone, hPL, PRL
                                                                                 Thyroid
↑ Iron requirement (maternal iron deficiency)
                                                                                      ↑ TBG
↑ Total WBC
                                                                                      ↑ Total T3, T4
↑ Clotting factors
                                                                                      hCG stimulates thyroid (↓ TSH)
Pulmonary system
Engorgement of nasopharynx, larynx, trachea, bronchi (capillary dilatations)          Iodine deficiency state (↑ renal clearance)
Voice change, breathing via nose difficult, CXR - ↑ vascular markings in lungs
↑ Tidal volume                                                                   Metabolism
↓ FRC (functional residual capacity)                                             ↑ Weight
↓ pCO2 (secondary to alveolar hyperventilation)                                      Uterus and its contents
↓ Bicarbonate (metabolic compensation)                                               Breast tissue, blood, water volume
↑ pO2 while upright (may fall when supine)                                           Average ↑ weight – 12.5kg
Pulmonary circulation                                                            CVS
    ↓ Pulmonary vascular resistance                                             Estrogen - ↑ RAA
    ↑ Pulmonary blood flow                                                      Stimulate erythropoiesis – progesterone, hPL, PRL
    ↑ Pulmonary blood volume                                                    CVS changes – due to a-v shunt through placenta (late pregnancy)
    ↑ O2 consumption (due to metabolic demands of fetus, uterus, placenta)      Pulmonary
                                                                                 ↑ Intraabdominal pressure (force diaphragm upward)
                                                                                 ↑ BMR of growing fetus - ↑ maternal O2 consumption, CO2 production
                                                                                 Progesterone – acts on CNS to ↓ set-point for regulation of respiration by CO2
                                                                                 (↑ Ventilation)
                                                                                 Renal
                                                                                 ↑ RAA (due to ↓ BP)
                                                                                 Estrogen stimulates liver synthesis of angiotensinogen
                                                                                 Estrogen, progesterone - ↑ ACE
                                                                                 ↑ DOC (placental deoxycorticosterone)
                                                                                     ↑ Mineralocorticoids
                                                                                     ↑ Aldosterone
                                                                                 CNS
                                                                                 ↑ Sensitivity to PaCO2
                                                                                 ↓ Volume of epidural space
                                                                                 ↑ Pressure of epidural space
                                                                                 ↓ CSF volume
↑ Dead volumes
                                                                                 ↑ CSF pressure
↑ Tidal volumes
                                                                                 ↑ Sensitivity to local anaesthetics
↓ Total lung capacity
                                                                                 ↓ Local anaesthetic dose
↓ Functional residual capacity, residual volume, respiratory reserve volume