Maternal plasma volume expansion and hormonal changes in women with idiopathic fetal growth retardation.
OBJECTIVE
To explore the mechanisms underlying the reduced maternal plasma volume associated with idiopathic fetal growth retardation (FGR).


METHODS
In 30 normotensive women with growth-retarded fetuses and 26 with normal-size fetuses, plasma volume was measured with a modified Evan's blue method. Plasma levels of atrial natriuretic peptide, plasma renin activity, aldosterone, estradiol, and progesterone, and urinary excretion of kallikrein, prostacyclin, and thromboxane A2 were measured at 34-40 weeks' gestation.


RESULTS
Compared with controls, gravidas with growth-retarded fetuses had a reduced plasma volume expansion (P < .01), similar atrial natriuretic peptide and plasma renin activity levels, and lower serum aldosterone (P < .001) and placental steroids (P < .03). These women also had decreased urinary kallikrein activity and prostaglandin excretion (P < .05). When both groups were combined, maternal plasma volume correlated significantly with birth weight (r = 0.53) and placental weight (r = 0.66).


CONCLUSIONS
Normotensive women with idiopathic FGR have reduced plasma volume expansion. Although the exact mechanisms of this change are unknown, we postulate that the lower maternal aldosterone levels and reduced levels of vasodilator substances, such as prostacyclin and kallikrein, may have a causal role.
Center for Medical Research, School of Medicine, Catholic University of Chile, Santiago.
S P
SP
Salas
P
P
Rosso
R
R
Espinoza
J A
JA
Robert
G
G
Valdés
E
E
Donoso
D000328:Adult; D000450:Aldosterone / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood; D011464:Epoprostenol / Q000652:urine; D004958:Estradiol / Q000097:blood; D005260:Female; D005317:Fetal Growth Retardation / Q000503:physiopathology*; D006728:Hormones / Q000378:metabolism*; D006801:Humans; D007610:Kallikreins / Q000652:urine; D010953:Plasma Volume / Q000502:physiology*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012083:Renin / Q000097:blood; D013928:Thromboxane A2 / Q000652:urine
D006728:Hormones; D000450:Aldosterone; D011374:Progesterone; D004958:Estradiol; D013928:Thromboxane A2; D009320:Atrial Natriuretic Factor; D011464:Epoprostenol; D007610:Kallikreins; D012083:Renin