Blood volume of pregnant and non-pregnant rats. Blood volume in rats fed control or low protein diet during pregnancy(A, n = 7-9) and in non-pregnant rats at different stages of the oestrus cycle (B, n = 6) Creatinine clearance (C, n = 4-8) in rats fed a control or low-protein diet during pregnancy. Data is presented as mean ± SEM and was analysed by one or two-way ANOVA, as described in the methods section. There was a significant effect of gestational age on blood volume (P < 0.05), but no effect of maternal diet. Blood volume varied with stage of oestrus (superscript letters denote a > b, P < 0.05) There was a significant interaction between gestational age and diet in their effects on creatinine clearance (P < 0.05).