Metabolic changes in pregnancy

Basal metabolic rate (BMR)

BMR increase to 20% above non-pregnant state at 36 weeks

Falls slightly to 15% above non-pregnant state baseline at term

Oxygen consumption

Oxygen consumption increase by 20% at term

NB:

[JN5:p320] Oxygen consumption increase by 15-30% at term

Carbohydrate metabolism

Insulin secretion increase from end of first trimester to 32 weeks, then declines to non-pregnant level at term

Impaired glucose tolerance

Tissue sensitivity to insulin diminishes

Increased level of hPL, free cortisol, oestrogen and progesterone may contribute

Fat metablism

Net storage of fat in the first half of pregnancy
--> Decreased FFA and glycerol in plasma

Mobilisation during second half
--> Increased FFA and glycerol in plasma

Amino acid metabolism

Maternal plasma level of amino acid falls due to

• Gluconeogenesis
• Transplacental transfer
• Loss in urine

NB:

• The foetus uses amino acids for protein synthesis and as an energy substrate