The renal excretion of nutrients in pregnancy.

A feature of normal pregnancy is a huge increase in the excretion of nutrients in urine. Glycosuria is commonplace, and about half of all healthy pregnant women excrete more than when not pregnant. Amounts in excess of 1 g/24 hr are common, and excretion is characteristically intermittent with little apparent relation to plasma levels. Amino acid excretion is also raised four or five times by late pregnancy, with a characteristic pattern for different amino acids, and folate and other water soluble vitamins are similarly squandered. The mechanisms are not understood.