title: [Reduced plasma volume and changes in vasoactive hormones in underweight pregnant women].
abstract: BACKGROUND
  Pregnant women with low weight/height (wt/ht) have lower plasma volume and reduced birth weight than women with normal wt/ht.
  
  
  OBJECTIVE
  To explore the hormonal mechanisms involved in these alterations.
  
  
  METHODS
  Plasma volume, and several hormones related to plasma volume regulation were determined in 24 near term pregnant women with low wt/ht and in 30 with normal wt/ht.
  
  
  RESULTS
  Newborns's weight, height and ponderal index were reduced in the low wt/ht group. Plasma volume (3042 +/- 101 vs 3631 +/- 101 ml, p < 0.001); plasma renin activity (7.5 +/- 0.9 vs 11.1 +/- 0.9 ng/ml/h, p < 0.01) and aldosterone (428 +/- 47 vs 710 +/- 58 pg/ml, p < 0.001) were significantly reduced in the low wt/ht group. Similar reductions were observed in serum estradiol and progesterone levels. Urinary kallikrein activity (354 +/- 112 vs 824 +/- 134 nmoles/24 h, p < 0.05), 6-keto-prostaglandin F1 alpha (561 +/- 90 vs 1121 +/- 165 ng/24 h, p < 0.05) and thromboxane B2 (110 +/- 29 vs 280 +/- 29 ng/24 h, p < 0.05) were also reduced in low wt/ht women.
  
  
  CONCLUSIONS
  We postulate that the reduced levels of vasoactive hormones observed in pregnant women with low wt/ht may interfere with plasma volume expansion and, in turn, cause low birth weight.
authors.affiliation: Departamentos de Obstetricia y Ginecología y Pediatría, Escuela de Medicina, Pontificia Universidad Católica de Chile. ssalas@osler.med.puc.cl
authors.forename: S P
authors.initials: SP
authors.lastname: Salas
authors.forename: P
authors.initials: P
authors.lastname: Rosso
mesh_terms: D000328:Adult; D000450:Aldosterone / Q000097:blood; D001827:Body Height / Q000502:physiology*; D001835:Body Weight / Q000502:physiology*; D004958:Estradiol / Q000097:blood; D005260:Female; D005317:Fetal Growth Retardation / Q000378:metabolism; D006728:Hormones / Q000378:metabolism*; D006801:Humans; D007223:Infant; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007610:Kallikreins / Q000652:urine; D010953:Plasma Volume / Q000502:physiology*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011374:Progesterone / Q000097:blood
chemical_list: D006728:Hormones; D000450:Aldosterone; D011374:Progesterone; D004958:Estradiol; D007610:Kallikreins