Every maternal organs adapts to pregnancy, each at a different time and in a different way. Maternal systems adapt as pregnancy progresses to accommodate the increasing demands of fetal growth and development. Management of both healthy and diseased pregnancy necessitates knowledge of the physiology of normal pregnancy. Understanding these adaptations enable clinicians to identify abnormal changes that lead to complications, as well as recognize changes that mimic disease, and understand altered responses to stress.

1.  Maternal Adaptation
Increased availibility
of precursors for
hormone production
& fetal-placental
metabolism
Increased
transport
capacity
Fetal-maternal
exchange
Removal
of
additional
waste
products

2.  Factors contributing to fluid retention
Sodiumretention
• Resetting of osmostat
Thirst threshold
• Plasma oncotic pressure

3. Haemoglobin concentration
• Haematocrit
Serum albumin concentration
• Stroke volume
Renal blood flow

4. Decreases in:
• Hb concentration
• Haematocrit
• Plasma folate concentration
• Plasma protein concentration
• Protein S activity
• Creatinine, urea, uric acid

5. Increases in:
• ESR
• Fibrinogen concentration
• Activated protein C resistance
• Factors VII, VIII, IX, X and XII
• D-dimers
• Alkaline Phosphatase

6. Ventilatory changes
• Thoracic anatomy changes
• Inc. Minute ventilation
• Inc. Tidal volume
• Decr. Residual volume
• Decr. Functional residual capacity
Blood gas and acid-base changes
• Decr. pCO2
• Incr. pO2
• pH alters little
• Incr. Bicarbonate excretion
• Incr Oxygen availibility to tissues and
placenta

7. HR (10-
20%)
SV (10%)
CO (30-
50%)
Inc.
MAP
(10%)
Pulse
Pressure
Peripheral
resistance
(35%)
Decr.

8. Kidney size
(1cm)
Blood flow
(60-75 %)
GFR (50%)
Renal plasma
flow (50-80%)
Inc Plasma
creatinine.
Urea and
ureate
Dec Dilatation of
renal pelvis
and ureters
Glycosuria is
normal

9. Prolactin
Coricosteroid
Inc
TSH in early
pregnancy
Ft4 in late
pregnancy
Decr

10.  Hyperpigmentation
 Striae gravidarum
 Hirsuitism
 Inc Sebaceous gland activity

11.  Obstetrics by Ten Teachers