PROTEIN-TURNOVER IN PREGNANCY

Whole-body protein metabolism was studied at 13, 24 and 35 weeks gestation in six healthy women using a continuous infusion [C-13]leucine technique. Values were expressed in terms of fat-free body weight (FFM) calculated using literature standards for changes in total body potassium during pregnancy. Mean protein synthesis increased from 5.3 (+/-0.6 SD) g/kg FFM/24h at 13 weeks to 5.9+/-0.5 (P<0.1) at 24 weeks and 6.1+/-0.6 at 35 weeks (P<0.05 vs 3 weeks). Similar increases were noted in catabolism so that net loss changed little. Protein synthesis at 24 and 35 weeks gestations was significantly greater than that in 17 healthy, non-pregnant women (14.9+/-0.6, P<0.001). These data indicate that there are substantial increases in protein turnover during pregnancy.