Plasma Volume, Renal Function, and Hormonal Levels in Pregnant Women with Idiopathic Fetal Growth Restriction or Preeclampsia

Abstract

Objective: To compare changes in maternal plasma volume, renal function, and several hormones related to volume regulation in pregnant women with idiopathic fetal growth restriction (FGR), mild preeclampsia (PE), and matched controls.Methods: Plasma volume, plasma renin activity (PRA), serum aldosterone, estradiol and progesterone levels, renal function, and urinary kallikrein activity were measured in 25 near-term normotensive pregnant women with FGR, in 25 women with mild PE, and in 37 normotensive controls with similar gestational age. Differences among the group means were determined by ANOVA.Results: Maternal age, weight, height, and renal function were similar in all groups. FGR and PE groups had significantly lower newborns' weight, length, and ponderal index. Plasma volume was significantly reduced in FGR (3040 ± 82 mL) and PE (3033 ± 105 mL) mothers when compared with controls (3564 ± 89 mL), P < 0.001. The PRA was lower in FGR (7.7 ± 0.9 ng/mL/h) and PE (5.8 ± 1.1 ng/mL/h) mothers than controls (11.1 ± 0.8 ng/mL/h), P <0.001; similar differences were observed in aldosterone levels. The progesterone/estradiol ratio was increased in PE when compared with the other groups (control = 9.6 ± 0.5; FGR = 8.0 ± 0.5; PE = 14 ± 1.3, P < 0.001). Urinary kallikrein activity was significantly reduced in FGR (432 ± 103 nmol/24 h) and PE (422 ± 92 nmol/24 h) mothers when compared with controls (788 ± 136 nmol/24h), P < 0.001.Conclusions: Present results confirm a strong association between plasma volume expansion and fetal growth. In addition, they indicate that FGR and mild PE mothers have a reduced plasma volume, lower PRA, aldosterone, and urinary kallikrein activity levels, suggesting a common pathophysiological alteration.