UREA PRODUCTION AND SALVAGE DURING PREGNANCY IN NORMAL JAMAICAN WOMEN

The pattern of aggregate nitrogen demand during pregnancy and the feta l and maternal components are unclear. Excess demand enhances efficien cy of nitrogen utilization. Urea salvage contributes to enhanced effic iency. Dietary protein intake, urea production, and salvage of urea ni trogen were measured in eight nonpregnant control subjects, and trimes terly in nine pregnant women. Production was measured after prime-inte rmittent intravenous doses of [N-15 N-15]-urea by dilution of label in urinary urea. Dietary protein intake was greater in trimester 1 than in nonpregnant women (167 +/- 36 vs 224 +/- 60 mg N.kg(-1).d(-1)), and increased further in trimester 2 (266 +/- 59 mg N.kg(-1).d(-1)). Urea production was not higher during pregnancy. Despite higher protein in take, urea salvage was higher in pregnancy (40 +/- 24 nonpregnant vs 7 7 +/- 23, 61 +/- 31, and 51 +/- 12 mg N.kg(-1).d(-1)). Therefore, the demand-supply gap for nitrogen was greatest early in pregnancy when fe toplacental growth is slowest, and implies heightened maternal demand.