1. Physiological Changes in Pregnancy

2. Increased availability of precursors for hormone production and fetal-placental metabolism ;
Improved transport capacity ;
Maternal-fetal exchange ; and
removal of additional waste products

3. Volume homeostasis

4. Factors contributing to fluid retention ↑Sodium retention
Factors contributing to fluid retention ↑Sodium retention . Resetting of osmostat ↓ Thirst threshold ↓ Plasma oncotic pressure . Consequences of fluid retention ↓ Haemoglobin concentration . ↓ Haematocrit ↓ Serum albumin concentration . ↑ Stroke volume

5. Haemostasis and Coagulation
Increases in :
Erythrocyte sedimentation rate ;
Fibrinogen concentration ; % ( 450 mg/dL ) .
Activated protein C resistance ;
Factors VII , VIII , IX , X and XII ;
D-dimers ;
Alkaline phosphatase .
Von-willebrand factor .
Antithrombin III unchanged
plasminogen – activator inhibitor ( PAI – 1 , 2 )

6. Decreases in :
Haemoglobin concentration .
Haematocrot .
Plasma folate concentration .
Protein S activity .
Plasma protein concentration , particularly albumin .
Creatinine , urea , uric acid

7. The immune response :
reduced numbers of cytotoxic ( CD8+ ) T cells during pregnancy , with potentially harmful T cell-mediated immune responses downregulated .
The total white cell count increases up to values of 14 x 109/L in the third trimester .
Counts of B cells appear to be unaltered numbers of natural killer ( NK ) cells increase in early pregnancy and decrease in late gestation .

8. Respiratory tract Ventilatory Changes: nasal congestion &rhinitis
Thoracic anatomy changes .
↑ Minute ventilation .
↑ Tidal volume .
↓ Residual volume .
↓ Functional residual capacity .
Vital capacity unchanged or slightly increased .
Pulmonary blood flow increased .

9. Blood gas and acid-base changes
↓PCo2
↑ PO2
pH alters little .
Bicarbonate excretion increased .
↑ Oxygen availability to tissues and placenta .
↑ O2 consumption by 45 ml/min .
Shifts of O2 – Hb dissociation curve to the right

10. Cardiovascular system
Elevation of the diaphragm , adjustments of lung volumes and increases in minute ventilation give rise to breathlessness .
Oedema in the extremities is a common finding .
Sinus tachycardia .
Premature atrial and ventricular ectopic beats are common in pregnancy .
Cardiac output increases

11. Decreases in diastolic blood pressure ( 10 – 15 mmHg ) are more marked during antenatal period than the decrease in systolic pressure ( 5 – 10 mmHg ) .
A 70 per cent reduction in peripheral resistance has been demonstrated by 8 weeks gestation .
At delivery , a shift of blood from the empty uterus into the maternal circulation – called autotransfusion .

12. The first heart sound is loud .
While a third heart sound is aubible in 84 per cent of pregnant women by 20 weeks gestation .
An ejection systolic murmur can be heard .

13. Cardiovascular changes
Heart rate ( 10 – 20 per cent ) .
Stroke volume ( 10 per cent ) .
Cardiac output ( 30 – 50 per cent ) 7 L / min .
Mean arterial pressure ( 10 per cent ) .
Pulse pressure .
Peripheral resistance ( 35 per cent ) .

14. Gastrointestinal changes
Pregnancy gingivitis .
Increased tooth mobility .
Elevated progesterone levels reduce lower oesophageal sphincter tone and increase the placental production of gastrin , increasing gastric acidity .
The enlarging uterus and progesterone levels all contribute to delayed gastric emptying .
Constipation .

15. kidneys and urinary tract
Kidney size ( 1 cm ) .
Dilatation of renal pelvis and ureters .
↑ Blood flow ( 60 – 75 per cent ) .
↑ Glomerular filtration ( 50 per cent ) .
↑ Renal plasma flow ( 50 – 80 per cent ) .
↑ Clearance of most substances : ca , protein .
↓ Plasma creatinine , urea and urate .
Glycosuria is normal .
K+ Metabolism unchanged .