Mother establishes some nutrient reserves to help her later
All vital organs in mothers body increases activity
All changes are controlled by hormones
Physiological adjustments during pregnancy
Basal metabolism increases by
5% in 1st trimester 12- 15 % in 2nd & 3rd trimester
Increase in thyroid function increases the BMR Increase in BMR in the 2nd half of pregnancy averages to 150k cal/ day
Gastric tone is decreased. Therefore nausea and vomiting are common.Gastrointestinal motility diminishes helping in increased absorption of nutrients as the food movement is slow. Absorption of calcium, iron, vitamin B12 etc is increased
Decreased ability to taste salt – A physiologic mechanism for increasing salt intake.
Increased progesterone level relaxes uterine muscle and allows expansion for foetal growth.
Changes in renal function is seen
GFR (Glomerular filteration rate) is increased and several waste products are cleared very fast. Water is excreted at higher rate in the mid pregnancy and at lower rate in advanced pregnancy
Increased loss of free fatty acids ; decreased loss of calcium and B-complex Vitamins
Plasma volume increases by 50% resulting in apparent decreased levels of Haemoglobin.
Red cell mass increases by 20%
The concentration of heamoglobin (Hb) and packed cell volume(PCV) falls despite increase in total Hb. This is called as the physiological anemia of pregnancy. Therefore the normal Hb level in pregnancy is 11g/dl.